Lands: Taming the Wilds (Natural Resources)

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Author: Julie Kerr Casper | Ph.d.

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NATURAL RESOURCES

Lands

NATURAL RESOURCES

Agriculture Animals Energy Forests Lands Minerals Plants Water and Atmosphere

Lands Taming the Wilds

Julie Kerr Casper, Ph.D.

Lands Copyright © 2007 by Julie Kerr Casper, Ph.D. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Chelsea House An imprint of Infobase Publishing 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Casper, Julie Kerr. Lands : taming the wilds / Julie Kerr Casper. p. cm.-(Natural resources) Includes bibliographical references and index. ISBN-10: 0-8160-6356-7 (hardcover) ISBN-13: 978-0-8160-6356-7 1. Land use-Environmental aspects-Juvenile literature. I. Title. II. Series. HD108.3.C37 2007 333.73-dc22 2006037262 Chelsea House books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755. You can find Chelsea House on the World Wide Web at http://www.chelseahouse.com Text design by Erik Lindstrom Cover design by Ben Peterson Printed in the United States of America Bang NMSG 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper. All links and Web addresses were checked and verified to be correct at the time of publication. Because of the dynamic nature of the Web, some addresses and links may have changed since publication and may no longer be valid.

Contents

1 2 3 4 5 6 7 8 9

Preface Acknowledgments Introduction

vi x xi

Concepts of Land Resources

1

The History of Land Use

30

Renewable and Nonrenewable Resources

55

The Development of Land Resources

73

Multiple Uses of the Land

100

The Importance of Land Resources

121

Management of Land Resources

139

Conservation of Land Resources

166

Conclusion: Future Issues and Sustainable Resources

Appendix Glossary Further Reading Index

186 199 201 215 218

Preface

Natural Resources: Priceless Gifts from the Earth

Mankind did not weave the web of life. We are but one strand in it. Whatever we do to the web, we do to ourselves . . . All things are bound together. —Chief Seattle

T

he Earth has been blessed with an abundant supply of natural resources. Natural resources are those elements that exist on the planet for the use and benefit of all living things. Scientists commonly divide them down into distinct groups for the purposes of studying them. These groups include agricultural resources, plants, animals, energy sources, landscapes, forests, minerals, and water and atmospheric resources. One thing we humans have learned is that many of the important resources we have come to depend on are not renewable. Nonrenewable means that once a resource is depleted it is gone forever. The fossil fuel that gasoline is produced from is an example of a nonrenewable resource. There is only a finite supply, and once it is used up, that is the end of it. While living things such as animals are typically considered renewable resources, meaning they can potentially be replenished, animals hunted to extinction become nonrenewable resources. As we know from past evidence, the extinctions of the dinosaurs, the woolly mammoth, and the saber-toothed tiger were complete. Sometimes, extinctions like this may be caused by natural factors, such as climate change, vi

PREFACE

drought, or flood, but many extinctions are caused by the activities of humans. Overhunting caused the extinction of the passenger pigeon, which was once plentiful throughout North America. The bald eagle was hunted to the brink of extinction before it became a protected species, and African elephants are currently threatened with extinction because they are still being hunted for their ivory tusks. Overhunting is only one potential threat, though. Humans are also responsible for habitat loss. When humans change land use and convert an animal’s habitat to a city, this destroys the animal’s living space and food sources and promotes its endangerment. Plants can also be endangered or become extinct. An important issue facing us today is the destruction of the Earth’s tropical rain forests. Scientists believe there may be medicinal value in many plant species that have not been discovered yet. Therefore, destroying a plant species could be destroying a medical benefit for the future. Because of human impact and influence all around the Earth, it is important to understand our natural resources, protect them, use them wisely, and plan for future generations. The environment—land, soil, water, plants, minerals, and animals—is a marvelously complex and dynamic system that often changes in ways too subtle to perceive. Today, we have enlarged our vision of the landscape with which we interact. Farmers manage larger units of land, which makes their job more complex. People travel greater distances more frequently. Even when they stay at home, they experience and affect a larger share of the world through electronic communications and economic activities— and natural resources have made these advancements possible. The pace of change in our society has accelerated as well. New technologies are always being developed. Many people no longer spend all their time focused in one place or using things in traditional ways. People now move from one place to another and are constantly developing and using new and different resources. A sustainable society requires a sustainable environment. Because of this, we must think of natural resources in new ways. Today, more

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than ever, we must dedicate our efforts to conserve the land. We still live in a beautiful, largely natural world, but that world is quickly changing. World population growth and our desire to live comfortably are exerting pressures on our soil, air, water, and other natural resources. As we destroy and fragment natural habitats, we continue to push nonhuman life into ever-smaller pockets. Today, we run the risk of those places becoming isolated islands on a domesticated landscape. In order to be responsible caretakers of the planet, it is important to realize that we humans have a partnership with the Earth and the other life that shares the planet with us. This series presents a refreshing and informative way to view the Earth’s natural resources. Agriculture: The Food We Grow and Animals We Raise looks at agricultural resources to see how responsible conservation, such as caring for the soil, will give us continued food to feed growing populations. Plants: Life From the Earth examines the multitude of plants that exist and the role they play in biodiversity. The use of plants in medicines and in other products that people use every day is also covered. In Animals: Creatures That Roam the Planet, the series focuses on the diverse species of animals that live on the planet, including the important roles they have played in the advancement of civilization. This book in the series also looks at habitat destruction, exotic species, animals that are considered in danger of extinction, and how people can help to keep the environment intact. Next, in Energy: Powering the Past, Present, and Future, the series explores the Earth’s energy resources—such as renewable power from water, ocean energy, solar energy, wind energy, and biofuels; and nonrenewable sources from oil shale, tar sands, and fossil fuels. In addition, the future of energy and high-tech inventions on the horizon are also explored. In Lands: Taming the Wilds, the series addresses the land and how civilizations have been able to tame deserts, mountains, Arctic regions, forests, wetlands, and floodplains. The effects that our actions can have on the landscape for years to come are also explored. In Forests: More Than Just Trees, the series examines the Earth’s forested areas and

PREFACE

how unique and important these areas are to medicine, construction, recreation, and commercial products. The effects of deforestation, pest outbreaks, and wildfires—and how these can impact people for generations to come—are also addressed. In Minerals: Gifts From the Earth, the bounty of minerals in the Earth and the discoveries scientists have made about them are examined. Moreover, this book in the series gives an overview of the critical part minerals play in many common activities and how they affect our lives every day. Finally, in Water and Atmosphere: The Lifeblood of Natural Systems, the series looks at water and atmospheric resources to find out just how these resources are the lifeblood of the natural system—from drinking water, food production, and nutrient storage to recreational values. Drought, sea-level rise, soil management, coastal development, the effects of air and water pollution, and deep-sea exploration and what it holds for the future are also explored. The reader will learn the wisdom of recycling, reducing, and reusing our natural resources, as well as discover many simple things that can be done to protect the environment. Practical approaches such as not leaving the water running while brushing your teeth, turning the lights off when leaving a room, using reusable cloth bags to transport groceries, building a backyard wildlife refuge, planting a tree, forming a carpool, or starting a local neighborhood recycling program are all explored. Everybody is somebody’s neighbor, and shared responsibility is the key to a healthy environment. The cheapest—and most effective— conservation comes from working with nature. This series presents things that people can do for the environment now and the important role we all can play for the future. As a wise Native-American saying goes, “We do not inherit the Earth from our ancestors—we borrow it from our children.”

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Acknowledgments

W

hile we deal with different aspects of the land every day, most people are not aware of just how much we depend on the land and its natural resources. We depend on the land as a source of many services—some obvious, others not so obvious. Obvious uses are to grow food on, to graze our animals on, and for the necessary building materials to construct our roads and homes with. Other, more subtle, values are the aesthetic characteristics enjoyed every time someone sets foot outside to enjoy nature, hike, camp, fish, or participate in any form of outdoor recreation. I hope to instill in you—the reader—an understanding and appreciation of the land and its vital role in our environment. Perhaps making you more aware of the land and all that it does for each one of us every day will plant in you the seeds of conservation toward this precious resource and encourage environmental awareness and the desire to protect this resource and use it wisely on a long-term basis—a concept called land stewardship. I would sincerely like to thank several of the federal government agencies that study, manage, protect, and preserve the land each day— in particular, the Bureau of Land Management (BLM), the U.S. Forest Service (USFS), the National Park Service (NPS), the U.S. Department of Agriculture (USDA), the Natural Resources Conservation Service (NRCS), and the U.S. Fish and Wildlife Services (FWS) for providing an abundance of learning resources on this important subject. I would also like to acknowledge and thank the many universities across the country (and their geography, ecology, and geology departments) as well as the private organizations that diligently strive to protect our precious land resources, not only at home but worldwide.

Introduction

T

he lands of the Earth hold vast resources. From mountains to deserts to forests to coastlines and grasslands, each environment—or ecosystem—offers a wide range of goods and services. It is difficult to assign a total dollar value to the land’s resources. Some values are quantifiable, such as the value of timber in forests, the grazing potential in grasslands, or the food that is grown on farms. The value of other resources is not as obvious, such as the aesthetic and recreational values of hiking trails and campgrounds in mountains, natural water filtration through aquifers, habitat for wildlife, carbon storage, biodiversity, soil fertility, or the land’s role in the water cycle. Some of these resources are renewable; others are not—but they are all important to the environment. Each component of an ecosystem plays a part in how the entire ecosystem functions; and many components are interrelated. If one land resource is mismanaged or depleted, it will often cause a ripple effect, upsetting the balance in other areas and damaging the entire system. Human impacts can have a tremendous influence on the land—both directly and indirectly. Cutting down a forested area to build a housing development and a road network is a direct effect. Polluting the atmosphere with greenhouse gases, which can pollute the environment, upset natural chemical balances such as the carbon cycle, and eventually lead to climate change that then affects the landforms and resources in that area, would be an indirect effect. When climate change causes drought, it can destroy farmers’ ability to grow crops on the land. The Earth’s landscapes can also tell a story. By understanding various landforms, it is possible to study past climates and determine which types of natural environments existed in the geologic past. Humans’ xi

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influence on the land tells its own story. For example, archaeologists use these concepts to study past civilizations to determine not only what their lifestyle was, but also what type of climate and vegetation existed at the time. Studying the landscape can answer many historical questions concerning the influence of both natural and human factors. Lands: Taming the Wilds addresses the important resource issues that we face today with the landscape, as well as future management of the land in order to preserve and protect its resources and provide responsible stewardship of the land for future generations to enjoy. Chapter 1 presents the concepts of how the Earth’s landmasses have changed over the geologic past, the effects of climate on the land, the role of ecosystems, and the resulting distribution of resources. Chapter 2 looks at the history of land use and its impact on civilization and then examines more closely the evolution of land exploration and use in the United States. Chapter 3 addresses the renewable and nonrenewable resources that are associated with rangeland, riparian corridors, wetlands, deserts, grasslands, wilderness areas, and parks and preserves. It also addresses natural resource exploration and extraction. Chapter 4 discusses the development of land resources and the role of several natural systems, such as the rock cycle, the role of soil, the water cycle, the nitrogen cycle, the carbon cycle, and the food chain. It also looks at natural hazards and the consequences of development within those areas. Chapter 5 focuses on use of the land, such as rangeland and grazing, agriculture and factory farming, the value of riparian areas, the impacts of urbanization, the use of fragile desert resources, irrigation and salinity, deforestation, pollution, and invasive species. Chapter 6 illustrates the importance of land resources and the goods and services that come from them, such as food, energy, carbon storage, tourism, wildlife habitat, medicines, minerals, clean water, soil stabilization, biodiversity, recreation, scenic beauty, and open space. Chapter 7 looks at the management of natural resources and the roles and responsibilities of the various government agencies throughout the country, as well as the responsibilities of each individual. It

Introduction

examines resource decision-making issues and the technologies available today to enable scientists and managers to be efficient stewards of the land. It examines emerging and cutting-edge management technologies involving geographic information systems (GIS), mathematical modeling techniques, remote sensing technologies, and real-time monitoring tools. Chapter 8 addresses the conservation of precious land resources. It presents the concepts of land stewardship and sustainability and the roles of designated wilderness, natural preserves and refuges, and national parks throughout the country. It also takes conservation to a personal level and illustrates how each individual can promote effective conservation. Finally, Chapter 9 looks at future issues and sustainable resources. It focuses on the importance of reducing, recycling, and reusing; con trolling land degradation; new technologies and developments; and our responsibility to work with nature to create a productive and healthy future.

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1

Concepts of Land Resources

I

n order to understand the land and the natural resources that landmasses have to offer, it is necessary to have an understanding of how they came to be. It is important to examine the types of natural landscapes—or biomes—that exist, the basic processes of soil formation, and practical uses of the land.

Origin of Landmasses The continents on the Earth have not always been in the same geographical locations that they are in today. At one point in geologic time, the world was made up of a single continent, called Pangaea. This “super continent” eventually separated and drifted apart, forming the seven different continents that exist today. In 1912, Alfred Wegener, a German meteorologist, was the first scientist to propose the theory of the drifting continents. He used the theory of Pangaea’s existence along with climate-related field data

LANDS

Plate tectonics has been at work since the Earth was formed. These reconstructions illustrate the movement of the continents from 620 million years ago to the present.

Concepts of land resources

collected from rocks. He believed that the continents are made of lighter rocks that rest on heavier crustal material—similar to an iceberg floating on water. Wegener proposed that the positions of the continents are not rigidly fixed, but instead, move at a slow rate—roughly one yard (one meter) per century. It was not until the 1960s, that geologists gained the technology to understand the processes at work that could move the Earth’s plates. The concepts of seafloor spreading and plate tectonics emerged as powerful new hypotheses to explain the features and movements of the Earth’s surface. Scientists concluded that the Earth’s surface was not composed of one large sheet, but was composed of more than 12 major pieces of crust. These pieces of crust are called plates. Each rigid plate, or slab, of lithosphere averages at least 50 miles (80 kilometers) thick. These plates move relative to one another at speeds of a few inches (centimeters) per year—at roughly the same rate as a human fingernail grows. Although these velocities are slow by human standards, they are extremely rapid by geologic ones. Plates can move 30 miles (50 km) in one million years, and the plates have already been in motion for 100 million years. Scientists recognize three common types of boundaries between the moving plates: (1) divergent, or spreading; (2) convergent; and (3) transform, or sliding.

Divergent or Spreading Plates Some adjacent plates are pulling apart, such as the Mid-Atlantic Ridge, which separates the North and South American Plates from the Eurasian and African Plates. This pulling apart causes a phenomena called seafloor spreading as new material is added to the oceanic plates. The best-known divergent boundary is the Mid-Atlantic Ridge. This ridge is a submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, but is just one segment of the global mid-ocean ridge system that encircles the Earth. The rate of spread along the Mid-Atlantic Ridge averages 1 inch (2.5 cm) per year, or 16 miles (25 km) in a million years.

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Convergent Plates Plates moving in opposite directions meet and collide with each other. One of the plates is dragged down, or subducted, beneath the other. The area where the plate sinks under the adjacent plate is called the subduction zone. Convergence can occur between oceanic-continental plates, oceanic-oceanic plates, and continental-continental plates. An example of a convergent plate is the Nazca Plate (oceanic), which subducts under the South American Plate to create the majestic Andes Mountains in South America. When plates push together, the Earth’s crust tends to buckle and be pushed upward or sideways. This is also how the Himalayan mountain range was formed. The Himalayas, towering as high as 29,000 feet (8,854 m), form the highest continental mountains in the world. Strong, destructive earthquakes and the rapid uplift of mountain ranges are common. When an oceanic plate subducts under another oceanic plate, a trench is formed. Trenches can be hundreds of miles (km) long and 5 to 7 miles (8 to 10 km) deep, cutting into the ocean floor. Transform or Sliding Plates The transform, or sliding, boundary is where one plate slides horizontally past another. Most transform faults are found on the ocean floor, offsetting some of the active spreading ridges and producing zigzag plate margins. Shallow earthquakes are associated with them. The best-known example of a sliding plate is the San Andreas Fault Zone in California. The San Andreas, which is 800 miles (1,300 km) long, slices through two-thirds of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of 2 inches (5 cm) per year. Land on the west side of the fault zone (Pacific Plate) is moving in a northwesterly direction relative to the land on the east side of the fault zone (North American Plate). Because the plates are internally rigid, they interact mostly at their edges. All plates move relative to each other.


The Force That Drives Tectonic Plates The tectonic plates do not randomly drift or wander about the Earth’s surface; definite, yet unseen forces drive them. Scientists believe that the relatively shallow forces driving lithospheric plates are also working with forces that originate much deeper in the Earth. From seismic and other geographical evidence and laboratory experiments, scientists generally agree with Harry Hess’s theory that the plate-driving force is the slow movement of hot, softened mantle

Although the Earth appears to be made up of solid rock, it is actually made up of three distinct layers: the crust, mantle, and core. Each layer has its own unique properties and chemical composition.

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This illustration shows significant plate tectonic processes and landforms, such as mid-oceanic ridges, hot spot volcanoes, subduction zones, mountain building, and volcano formation.

that lies below the rigid plates. Scientists also accept that the circular motion of the mantle carries the continents along, much like a conveyor belt. Below the lithospheric plates, the mantle is partially molten and can slowly flow in response to steady forces applied for long periods of time. When solid rock in the Earth’s mantle is subjected to heat and pressure in the Earth’s interior over millions of years, it can be softened and molded into different shapes. The movement within the mantle moves as a convection cell in a circular motion, similar to heating a pot of thick liquid to boiling. The heated liquid rises to the surface, spreads, and begins to cool; then it sinks back to the bottom of the pot where it is reheated, rises again, and repeats the process. Convection in the Earth is much slower than that of boiling, thick liquid, however. In order for convection to occur, there


must be a source of heat. Heat within the Earth comes from two main sources: radioactive decay and residual heat. Radioactive decay is a spontaneous process that involves the loss of particles from the nucleus of an isotope (the parent) to form an isotope of a new element (the daughter). Radioactive decay of naturally occurring chemical elements (such as uranium, potassium, and thorium) releases energy in the form of heat, which slowly migrates toward the Earth’s surface. Residual heat is gravitational energy left over from the formation of the Earth 4.6 billion years ago. How and why the escape of interior heat becomes concentrated in certain regions to form convection cells is somewhat of a mystery. Scientists do believe, however, that plate subduction plays a more important role than seafloor spreading in shaping the Earth’s surface features and causing the plates to move. The gravity-controlled sinking of a cold, denser oceanic slab into the subduction zone, dragging the rest of the plate along with it, is considered to be the driving force of plate tectonics. Scientists know that forces deep within the Earth’s interior drive plate motion. However, because these powerful forces are buried so deeply, no mechanism can be tested for directly and proved beyond a doubt. The fact that the tectonic plates have moved in the past and are still moving today is known, but the details of why and how they move will continue to challenge scientists in the future. Because the Earth’s plates have been in motion for millions of years, there has been plate movement of hundreds of miles (hundreds of km). For example, seafloor spreading over the past 100 to 200 million years has caused the Atlantic Ocean to grow from a tiny inlet of water between the continents of Europe, Africa, and the Americas into the vast ocean that exists today. The oceanic trenches are the deepest parts of the ocean floor. One of the most famous trenches is the Mariana Trench, located in the Pacific Ocean just east of the Mariana Islands near Japan, where the faster-moving Pacific Plate converges against the slower-moving Philippine Plate. The Challenger Deep, at the southern end of the Mariana Trench, plunges deeper into the Earth’s interior—35,838 feet

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The Earth is made up of a dozen or so major plates and several minor plates. Tectonic plates are constantly on the move. The fastest plate races along at 6 inches (15 cm) per year while the slowest plates crawl at less than 1 inch (2.5 cm) per year. Most plates are part continental and part oceanic.

(10,923 m)—than Mount Everest, the world’s tallest mountain, rises above ground. The Challenger Deep is the deepest known point in the oceans, and is caused by the subducting ocean crust dragging the edge of the continental crust down with it as it descends. It gets its name from the British survey ship Challenger II, which initially located the deep water off the Mariana Islands in 1951. Its exact depth was discovered by the Japanese in 1984, from data obtained by an instrument called a multi-beam echo sounder. The pressure is tremendous at this depth—scientists believe it is 16,000 pounds per square inch. Oceanic-oceanic plate convergence also results in the formation of volcanoes. Over millions of years, the erupted lava builds up on the ocean floor until the submerged volcano rises above sea level to become


The Pacific Ring of Fire is a zone of frequent earthquakes and volcanic eruptions that encircles the basin of the Pacific Ocean. It is shaped like a horseshoe and it is 24,856 miles (39,993 km) long. It is associated with a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and/or plate movements. It is sometimes called the circum-Pacific seismic belt.

an island volcano. Earthquakes are common along these areas, as well. The most famous example of this is the Pacific Ring of Fire—a ring of active volcanoes ringing the Pacific basin as a result of plate tectonics. Not all plate boundaries are as simple as the three types of boundaries mentioned above, however. In some regions, the boundaries are not well defined because the plate movement deformation occurring there extends over a broad belt—called a plate boundary zone. These areas typically have larger plates with several smaller fragments of plates, called microplates, involved.

Rates of Motion Scientists can determine the rates of plate movement over geologic time by analyzing the ocean’s floor “magnetic striping.” Small grains of magnetite, which are found within the volcanic basalt that makes

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up the ocean floor, act like magnets. The grains of magnetite naturally align themselves with the orientation of the Earth’s magnetic field. When the magma solidifies, it effectively records the Earth’s magnetic orientation (polarity) at the time it cools. Because the ocean plates are moving away from the magma source (seafloor spreading), it creates a “stripe” of basalt with the magnetite aligned to the current “north” pole. Scientists know that the Earth’s polarity reverses in intervals over time (the North becomes South and vice versa). When these polarity reversals occur, the magnetic striping records the flip-flops in the Earth’s magnetic field. In other words, a sequence of basalt may have its grains oriented to the North followed by a sequence that has its grains oriented to the South. Because scientists can calculate the approximate duration of each reversal, they can calculate the average rate of plate movement during a given time span. Evidence of past rates of plate movement can also be obtained from geologic mapping studies. If a rock formation of known age is mapped on one side of a plate boundary and can be matched with the same formation on the other side of the boundary, then measuring the distance that the formation has been offset can give an estimate of the average rate of plate motion.

The Effects of Climate on the Land Climate is the characteristic condition of the atmosphere near the Earth’s surface at a certain place on Earth. It is the long-term weather of that area. This includes the region’s general pattern of weather conditions, seasons, and even weather extremes such as hurricanes or droughts. Two of the most important factors determining an area’s climate are air temperature and precipitation. The world’s different habitats—or biomes—are controlled by climate. The climate of a region will determine what vegetation will grow there, what animals will inhabit the area, and what resources naturally occur. The climate system is based on the location of hot and cold air mass regions and the atmospheric circulation patterns created by the trade winds and westerlies.


The circulation pattern of the Earth’s atmosphere is divided into distinct zones and has a direct influence on the climate of any particular area. (Source: U.S. Geological Survey)

The trade winds north of the equator blow from the northeast. South of the equator, they blow from the southeast. The trade winds of the Northern and Southern Hemispheres meet at the equator, which causes the air to rise. As the rising air cools, clouds and rain develop. The resulting bands of cloudy and rainy weather near the equator create the tropical conditions. Westerlies blow from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere. Both the

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The Earth can be divided up into climatic zones, based on temperature, moisture, and airflow.

westerlies and trade winds blow away from the 30° latitude belt. Over large areas of this latitude, surface winds are light. Air slowly descends to replace the air that is flowing away from the region. The intense heat causes all the moisture in the air to evaporate, which causes the tropical desert regions—such as the Sonoran Desert in Mexico and the Sahara in Africa. There are three basic climate groups: (1) low-latitude climates; (2) mid-latitude and subtropical climates; and (3) high-latitude climates. The low-latitude climates are controlled by equatorial tropical air masses. In the tropical rain forest, rainfall is heavy in all months. The total annual rainfall can be as much as 100 inches (250 cm). There are seasonal differences in monthly rainfall, but temperatures


of 80°F (27°C) mostly stay constant. Humidity falls between 77% and 88%. “Equal” day lengths and high cloud cover also characterize these areas. The tropical monsoon climate has summer-onshore/winteroffshore air movement related to the monsoonal air circulation in the area; it has heavy, high-sun rain periods and short, low-sun drought periods. These areas include the coastal areas of southwest India, southwestern Africa, and northeast and southeast Brazil. Wet-dry tropical climates have a seasonal change that occurs between wet tropical air masses and dry tropical air masses. As a result, there is a very wet season and a very dry season. Trade winds dominate during the dry season. It gets a little cooler during this dry season but gets hot just before the wet season. In the dry tropical desert biome, climates in the low-latitude deserts are located between 18° to 28° latitude in both hemispheres. These latitude belts are centered on the Tropic of Cancer and the Tropic of Capricorn, which lie just north and south of the equator. The winds are light, with a hot, dry heat. These areas are very dry and arid and cover 12% of the Earth’s land surface. The tropical steppe climate occurs near the deserts in Australia, Argentina, southwest Asia, Africa, and the western United States. These areas are considered semiarid, with annual rainfall distribution similar to the nearest humid climate. The largest controlling factor in these areas is the descending, diverging circulation of subtropical highs. The climates in the mid-latitude zones are affected by two different air masses. The tropical air masses that are moving toward the poles and the polar air masses that are moving toward the equator. These two air masses are in constant conflict. Either air mass may dominate the area, but neither has complete control. The climates in this zone include humid subtropical, dry summer subtropical (Mediterranean), humid continental, marine west coast, mid-latitude desert, and mid-latitude steppe. The humid subtropical climate has a high humidity content, with summers like the humid tropics and winters with frost from polar air masses. Mediterranean climates are characterized by mild, moist

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How Land Cover Changes Affect Summer Climate According to the National Aeronautics and Space Administration (NASA), while carbon dioxide emissions, aerosols, and other factors may impact climate, a new study offers further evidence that land surface changes may also play a significant role. A study of the United States’ summer climate, using data and computer models from NASA, reported that changes in land cover, particularly vegetation, over the past 300 years have impacted regional temperatures and precipitation. Studies have shown that the largest human impacts on nature have occurred since the Industrial Revolution. NASA’s Ecosystem Computer Model was designed to trace the evolution of vegetation distribution patterns over the United States since the 1700s. The computer model was a technological breakthrough that enabled scientists to study the potential impacts of land use and climate change across various regions. NASA concluded that since 1700, land cover changes produced a significant cooling effect of more than 1°F (−17.22°C) in parts of the Great Plains and Midwest as agriculture expanded and replaced grasslands. Farmlands tend to create lower temperatures through increased evaporation. In addition, a warming effect was found along the Atlantic Coast, where croplands have replaced forests. Compared to forests, croplands are less efficient in transpiration. A slight warming was also observed across the Southwest where woodlands replaced some deserts. The study also found that land cover changes can impact local precipitation, but not as significantly as they affect temperature. Researchers do say, however, that the relatively strong cooling over the central United States has probably weakened the temperature difference between land and the Gulf of Mexico, slowing the northward movement of weather systems and resulting in enhanced rainfall across Texas. Air masses reaching the central lowlands regions are drier, causing reductions in rainfall. NASA scientists have also determined that certain types of land cover change can decrease or increase greenhouse warming.


winters and hot, dry summers. Hot, humid summers and occasional winter cold waves characterize the humid continental climates. Mild winters and mild summers characterize marine west coast climates, such as those found in coastal Oregon, Washington, and British Columbia. Mid-latitude desert climates are arid (low relative humidity) and have irregular rainfall. Mid-latitude steppe climates—such as in inner Asia and the western United States—are semiarid with larger temperature ranges and more rainfall than tropical steppe areas. The high-latitude climates have polar and Arctic air masses that dominate these regions. Canada and Siberia are two air-mass sources that fall into this group. A Southern Hemisphere counterpart to these continental centers does not exist. Air masses of Arctic origin meet polar continental air masses along the 60th and 70th parallels of latitude. Sub-Arctic climates have brief, cool summers, and long, bitterly cold winters. They also have the largest annual temperature ranges of any climate. Tundra climate, found in Greenland, Eurasia, the Arctic Ocean, and bordering lands of North America, is characterized as being “summerless”—these areas experience below-freezing temperatures at least nine months of the year. Precipitation is usually less than 10 inches (25.4 cm), and these areas have low evaporation rates. Ice cap climates are located in the interior regions of high-latitude landmasses. Covered by ice, they have a year-round influence of polar anticyclones. These areas have no summers—all months are below freezing. These areas contain the world’s coldest temperatures. Climate is a major factor in the creation of landforms that exist in particular places on the Earth. This in turn determines the resources present at a given location and the types of land use in which humans can engage.

Types of Natural Landscapes— The World’s Major Biomes Biomes are defined as the world’s major communities, classified according to the vegetation that grows there and described by the adaptations of living organisms to those particular environments. Although there

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The major biomes of the Earth. Each biome has specific plants associated with it.

are several ways that scientists classify biomes, the major biome types are mountains, tundra, temperate forest, marine/island, desert, tropical dry forest, cold-climate forest, grassland, savannah, and tropical rain forest. Biomes are not constant—they have changed and moved many times during the history of life on Earth. For example, as the Earth’s plates have moved and climates have changed, an area that is desert today may have been an aquatic or forest ecosystem millions of years ago. More recently, human activities have drastically altered ecosystem communities and landscapes. For example, some forest areas that have been overcut and poorly managed have become as barren and nonfertile as a desert. As biomes become changed or destroyed, it is critical for humans to understand the impact their actions can have on the


This illustration shows the major ecological regions of North America.

natural landscape. Interference with the natural landscape impacts the available resources and their quality. An ecosystem is an area on the Earth that is a community of living organisms and their surrounding environment. Every person, animal, plant, rock, stream, and piece of land belongs to one or more ecosystems. For example, an ecosystem can be made up of a freshwater pond that serves as a home for frogs, lily pads, fish, cattails, dragonflies, algae,

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mosquitoes, and protozoa. Each of these organisms, along with its sources of food, sediments, nutrients, and the water itself, is a part of the pond ecosystem, which functions as a unit or a single community. This pond could also lie deep inside a forest. The pond and its inhabitants belong to the larger forest ecosystem, which also contains several rivers, other ponds, many kinds of wildlife, flowering plants, and trees. Ecosystems on Earth are incredibly diverse, both in size and in form—a large city that contains millions of people, their homes, and a built-up landscape is an urban ecosystem, while a small wildlife preserve within that city serves as a natural ecosystem. Much like a person, an ecosystem has a given level of health. A healthy ecosystem performs many valuable functions, such as flood control, water purification, seed dispersal, pollination, pollutant removal, nutrient cycling, and habitat provision. These functions are beneficial to both humans and other inhabitants of ecosystems. Many ecosystems experience the effects of disturbances. These disturbances can be caused by human actions, such as bulldozing a forest to build a highway, or they can be a result of natural events, such as soil erosion from heavy rains. Humans have affected ecosystems in many different ways. Any time a forest is cut down, natural lands are cultivated, towns are built, a river is dammed, a factory is built, or lands are mined, the ecosystem is altered in some way. Humans have disrupted food chains, the carbon cycle, the nitrogen cycle, and the water cycle. Disturbances often decrease the ability of an ecosystem to provide valuable functions and thereby decrease the health of the ecosystem. A feature of ecosystems, from the smallest backyard to the entire globe, is that they tend to be resilient. Given time, ecosystems can often recover from disturbances, maintain their health, and continue to provide the functions necessary to sustain life on Earth.

Mountain Biome Mountains make up one-fifth of the world’s landscapes. Today, more than two billion people depend on mountain ecosystems for most of their food, hydroelectricity, timber, and minerals. About 80% of the Earth’s freshwater originates in mountain areas.


a

b

c

d

(a) A tropical island biome, Kauai, Hawaii, is a tourist destination for thousands of people each year. (b) Cacti are common in desert regions, such as this desert near Phoenix, Arizona. Cacti have adapted to extremely dry conditions by having thick, waxy coverings and needles instead of leaves. (c) Mountain biomes offer recreational opportunities and scenic beauty. (d) The arctic biome hosts a multitude of glaciers, some which are several hundred feet thick. (a, b, c, photos by Nature’s Images; d, National Oceanic and Atmospheric Administration)

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All mountain biomes share a similar characteristic—rapid changes in altitude, climate, soil, and vegetation over very short distances. Because of these variabilities, mountainous areas support a wide range of biodiversity. Rainfall and temperature vary greatly in mountain biomes. For example, lightning and thunderstorms can appear rapidly, and temperatures can drop from extremely hot to below freezing in just a few hours. In addition to freshwater, mountain biomes provide many resources, such as farming, logging, mining, hunting, recreation, and aesthetic resources. Scientists believe the cures to many diseases may be found in the plants in mountain biomes. For example, the Himalayan yew—a slow-growing conifer—is a promising source of a drug called Taxol, which scientists believe can help cure cancer.

Tundra Biome Tundra exists in the highest northern latitudes and in the Southern Hemisphere in the Antarctic Peninsula and nearby islands. This biome covers about one-fifth of the Earth’s land surface. Because temperatures can drop to −50°F (−122°C) in the winter, it is impossible for trees to grow here. Instead, the tundra landscape is dominated by lowgrowing plant life and wildflowers. Much of the ground is permafrost (continually frozen). Only the top layer of the soil’s surface is able to thaw during the extremely short summer months. Despite these harsh physical conditions, many animals live in this biome. Hordes of insects provide resources for feeding thousands of birds who migrate through the area to take advantage of this food source, including waterfowl and shorebirds, ravens, hawks, ptarmigans, and owls. There is also a rich resource of animals in this biome, including the caribou, arctic hare, weasel, polar bear, mink, wolf, wolverine, walrus, lemming, brown bear, arctic fox, and reindeer. Temperate (Deciduous) Forest Biome The temperate forest biome is found in the middle latitudes around the world, such as eastern North America, Western Europe, and eastern Asia. This biome is seasonal. Because the trees are deciduous (meaning


they drop their leaves in the fall), their leaves change colors as the seasons go through their cycles. The temperate forest biome is one of the most altered biomes on Earth due to human activities in this area. The impact is great because the population density of the world closely corresponds to the distribution of temperate forests. Humans use the wood found in these areas for the construction of homes and buildings and for firewood. Many of these forests have been cleared for farming and to build communities. In fact, human activity has led to the decline and loss of these forests in many locations throughout the world.

Marine/Island Biome Islands can vary tremendously in characteristics, such as size, shape, and climate. Some islands are tropical and lush, providing resources such as fruit and wood. Other islands are very arid. Because of islands’ variability, the island ecosystem worldwide supports a wide variety of plant and animal life. There are two major categories of islands—continental and oceanic. Continental islands were once part of a larger landmass and, in recent geologic time, have become separated from the main continent by natural forces, such as rising sea level. Oceanic islands are created from the lava of giant underwater volcanoes—such as the islands of Hawaii. Oceanic islands are usually located far from large landmasses. The natural resources found on islands are very diverse, from food, wood, and fiber to endangered species and aesthetic values. Desert Biome Of all the Earth’s biomes, deserts have the driest climate. Many of the world’s deserts lie between 20° to 30° north and south latitude. As we saw in the Earth’s major circulation patterns, the desert zone is where air sinks toward the Earth’s surface and rainfall is rare because rain usually occurs where air begins to rise, not sink. Major deserts are found in North Africa, southwestern North America, the Middle East, and Australia. Desert regions only receive a few inches (cm) of rain each year. Some deserts receive no rainfall. Desert soils are often salty because

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whatever little rain that does fall quickly evaporates from the ground, leaving salt and other minerals behind—minerals that can be mined as natural resources for their commercial value. Vegetation in deserts varies widely, depending on the location. In deserts, the plants are drought-tolerant and can survive for long periods of time with no water. Many plants adapt unique features to ensure their survival, such as thick, waxy leaves; large root systems; tap roots; and water storage capabilities. The desert animals—such as jackrabbits, owls, snakes, lizards, and tortoise—have also adjusted to extreme temperature and drought. These animals are typically more active at night and around dawn and dusk, so that they avoid the scorching heat. Unfortunately, because of the careless behavior of humans, deserts are spreading over regions where there was once green, fertile land—a process called desertification. With good resource management skills, these lands can recover over time.

Tropical Dry Forest Biome These forests have high temperatures throughout the entire year and a well-defined dry season. This biome occurs in areas of slightly lower rainfall that are found next to tropical rain forests. The transition from tropical dry forest to tropical rain forest is not always clear-cut—the transition can change gradually over hundreds (km) of miles. The dry season limits plant growth and the activity of animals. These forests exist in Central America, southern Asia, and Australia. Cold-climate Forest Biome Cold-climate forests are also referred to as the taiga. These cold climate forests are found at very high latitudes extending across Eurasia and North America. The principal trees in these forests are coniferous (the trees carry cones). Rainfall in these areas is moderately high but is spread throughout the year, with snow covering the ground during the winter months. These areas usually contain many ponds or bogs—also called muskegs—because the sun evaporates very little water.


Because of the extremely cold temperatures, the trees use a lot of energy to grow their leaves. Pine trees grow needles instead of leaves, which is advantageous because they keep their needles all year round. Trees of this biome are also known as boreal, or as the northern coniferous forests. Along riverbanks in these regions, willows and other trees grow. Several species of animals migrate to the taiga in the summer months.

Grassland Biome Throughout the world, grasslands are known by many different names. For example, in North America they are called a prairie; in South Africa, they are known as a veldt; in Asia, they are a steppe; and in South America, they are called the pampas. This biome exists in temperate regions and is highly seasonal. Grassland areas can be huge—sometimes extending thousands of miles (km) in North America and Asia. Because grasslands are located in temperate regions, they have hot summers that eventually dry the grasses out and freezing winters dominated by powerful winds that sweep over the vast open areas. The rainfall in grasslands is less than the temperate forests receive, but more than deserts. In areas where rainfall is greater, the grass can grow very lush and thick. In the spring, many grasslands support large fields of beautiful wildflowers. Wildfires also play an important role in this ecosystem. They allow the grasslands to be open and free of shrubs and trees. This is important, because if shrubs begin to grow in grassland areas, it would not take long for them to overrun and kill off the grass, transforming the area into a shrubland. The plants in the grasslands have adapted over time to the wildfires and actually need them to keep healthy and grow new vegetation in the spring. Grassland soil, usually deep, dark, and rich, is called mollisol. In drier regions, it is called aridisol. Because a lot of this soil is very rich, many of the grasslands have been converted to agriculture. Grasslands are major regions for growing crops, such as wheat and

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corn. Grasslands also provide a food source for bison, deer, horses, and cattle.

Savannah Biome The savannah regions are tropical grasslands, found largely in Africa, India, and the northern regions of South America. Although located in the tropical latitudes, they are much drier than tropical forests. Rainfall averages from 20 to 60 inches (51 to 152 cm) a year and is seasonal— usually falling within a time period of a few weeks. Vegetation grows after the rainfall occurs; then long periods of drought follow. The dominant plant life includes grasses and small plants. Trees also grow in the savannah, such as palm trees and thorn woodlands. There are a lot of fruit trees, which provide a food source for many birds and animals. The savannah supports a wide diversity of animals. Types of birds include gray louries, flycatchers, purple-crested louries, hornbills, green pigeons, and raptors. Mammals in this biome include lions, leopards, cheetahs, elephants, buffaloes, giraffes, hippopotami, rhinoceroses, gazelles, zebras, kudus, and waterbucks. Tropical Rain Forest Biome The tropical rain forest biome contains the richest biodiversity of all the world’s biomes—containing the most animal and plant species. Unfortunately, the rain forests face the greatest threat from humans. Rain forests are being destroyed at record rates—an area equivalent to 50 soccer fields disappears each minute. Rain forests offer a supply of diverse resources—such as future medicinal cures for deadly diseases. Already, many drugs have been discovered that are contained within the plants of the rain forest. Many scientists fear that if species are destroyed, the possible life-saving therapeutic drugs will also be lost. These forests receive huge amounts of rainfall—from 13 to 26 feet (4 to 8 m)—each year. They are found mainly in Central and South America, Southeast Asia, and West Africa. They occur along the equator where temperatures and humidity are


extremely high. Because of the flow and moisture of the massive air masses, it rains almost 24 hours a day. In some regions, there can be more than 15 feet (4.5 m) of rain each year. Rain forests provide some of the most diverse natural resources on Earth.

The Importance of Soil Fertile soil is one of the land’s most important natural resources, because everything that lives on land depends directly or indirectly on soil. For example, without soil, farmers could not grow plants, which means they could not grow food for animals or people. Soil is considered a nonrenewable resource because it forms so slowly that it can take hundreds of years for just a few inches (cm) to form. A well-developed soil that is extremely fertile could have taken thousands of years to develop. Because of this, soil resources must be well managed. If nutrients are removed, or if the soil is eroded or overused, vegetation will not grow well. Soil is much more than just dirt. It contains particles of sand, silt, and clay, called inorganic particles. The proportion of these three types of particles helps determine the soil type. Soil that is high in sand is easy to work with because it has a lot of open air spaces between the sand grains. This makes sand the least fertile soil because the water drains through it quickly, carries away plant nutrients, and leaves the soil dry. Clay soils are more difficult to work with because they tend to be sticky; however, they hold more nutrients. Well-drained soils that contain a lot of organic matter are the most fertile soils. The type of soil and what actually goes on in the soil determine how well plants grow. Five factors determine what types of soil form on Earth: (1) parent material, (2) organisms, (3) topography, (4) climate, and (5) time. Parent material is the primary material from which the soil is formed. Soil parent material can be bedrock; organic material; deposits from water, wind, glaciers, and volcanoes; or an old soil surface. Bedrock is broken down as weathering processes wear away the mineral particles from rocks.

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Organisms that live in the soil along with decaying organic matter from leaves and dead plants change the soil’s chemistry. The most fertile soils have healthy amounts of nitrogen (N), phosphorus (P), and potassium (K). In order to grow healthy and strong, plants need these three elements. Topography, or how steep or flat the land is, also affects soil through its reaction to climatic processes. For example, soils at the bottoms of hills get more water than soils on slopes. Soils on slopes that face the sun are drier than soils on slopes that do not face the sun. Topography also affects mineral accumulations, type of vegetation, plant nutrients, erosion, and location of streams, which in turn affects soil formation. Climate plays an important role. Heating, cooling, wetting, and drying all help break down the parent material that forms the soil. Climate also determines how fast this breakdown occurs. Time is a critical factor. The longer the natural soil-forming processes occur, the more soil is formed. Soil protects plant roots from exposure to the sun’s heat. It also filters pollution that comes from rain and water runoff from farms. Plants utilize soil to grow and receive support while they grow. Soil formation, which is a long, involved process, eventually develops into distinct horizons (horizontal layers). When all the soil horizons are studied, it is called a soil profile. The surface of the profile is called the topsoil. The horizons underneath are called the subsoil, and at the bottom of the profile is bedrock. The soil can either be formed in situ (in place) from the weathering of the rock material found in the area, or it can be made from sediments that were initially deposited by wind, water, or ice from somewhere else. There are many different types of soil found throughout the world, depending on the rock material they were made from. Soil also has other important components. It must contain water, air pockets, and microorganisms. Tiny organisms live on decaying plants in the soil, turning the plants into humus. Humus makes soils more productive because it helps soil absorb heat, hold more moisture, and provide food for plants.


Soil produces almost all our food and fiber. Even crops grown in a water environment—like rice—rely on the nutrients found in soil. Soil, a valuable resource, provides 13 of the 16 nutrients needed for plant growth: nitrogen, phosphorus, calcium, sulfur, copper, boron, zinc, manganese, molybdenum, chlorine, iron, magnesium, and potassium. These nutrients come from the weathered minerals and decayed plant matter found in the soil. Carbon, hydrogen, and oxygen are stored in the air spaces between soil particles. Soil also helps filter and purify water. When water travels over or through soil before entering rivers or lakes, the soil helps prevent flooding by allowing excess water to soak in for use by plants or to percolate (flow through) to other underground water bodies, which are called aquifers. Soil helps purify contaminated water by removing the impurities and killing potential disease-causing organisms. Soil is important because it recycles dead plants and animals into the nutrients needed by all living things. Erosion—by wind or water—is the most serious threat to the health of the soil.

Land Use in the United States The three major uses of the land in the United States are grassland pasture and range, forest-use land, and cropland, in that order. Total cropland (used for crops or pasture, or idled) has trended down slightly since the late 1960s. In the United States, land is the first factor of production. The land’s potential uses and its location determine its economic value. Land use can affect the environment and the sustainability of production. Competition and conflicts occur among users of land because land used in one way often prevents or reduces other uses. Grassland pasture and range (the largest use of the land) involves 589 million acres (31% of major land uses). Rangeland used for grazing has declined in recent years, however, because researchers and farmers have improved the forage quality and productivity of grazing lands. Forest-use land is primarily used for timber production. Forested areas that are not used to harvest timber are protected in various national and state parks, wilderness areas, and wildlife areas.

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a

b

c

(a) Wild horses live in the rangelands of the American Southwest. (b) Forests are important sources for timber. (c) A farmstead in Green County, Wisconsin. (a, photo courtesy of the Bureau of Land Management; b, photo by Nature’s Images; c, courtesy of the U.S. Department of Agriculture, photo by Ron Nichols)


Major Land Uses Land use

Acreage (in millions of acres)

Proportion of land

Cropland

460

24.3

Grassland pasture and range

589

31.1

Forest-use land

559

29.5

Special uses *

194

10.2

Miscellaneous uses ** 92 4.9 (Source: United States Department of Agriculture) *Urban land, transportation, recreation and wildlife areas, and national defense areas. **Marshes, swamps, and wetlands.

The cropland areas in the United States provide an abundance of food at home and all around the world. The use of genetic engineering and better nutrients have made farming land much more productive. Our advanced technology has made it so that fewer people need to spend time farming in this country. While land in every use occurs all over the United States, some uses are more concentrated in some regions than others. Regions with the largest cropland acreages are the northern Plains, corn belt, and southern Plains. Grassland pasture and range is concentrated in the mountain and southern Plains regions. Acreages in forest-use and special uses are highest in the mountain regions.

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CHAPTER

2

The History of Land Use

T

hroughout time, the land has been used for many different things. Through the study of geology and climatology, scientists are able to piece together the Earth’s past and utilize resources connected to past geologic conditions. In addition to the natural evolution of the landscape and the Earth’s resources, humans have impacted the land. Archaeologists—scientists who study past human civilizations—are able to fit pieces of the historical puzzle together concerning human use of the land as well as the climatic conditions that existed at the time of past civilizations. Historians have recorded land use over many centuries in different parts of the world, and their accounts offer additional insight into the taming of the land. Land use and exploration has also shaped the story of the United States—from the time explorers set out west to open the entire country and utilize its vast treasure of natural resources to the evolution of settlement, farming, and land conservation.

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The history of land use

As populations have increased and cities have grown, humans have had the biggest impact of all on the land and its resources. This chapter examines the issues that have shaped the landscape as we know it today.

Clues to the Past—Geologic Time and Climatology Rocks tell the story of the Earth. The Earth is made of rock, from the tallest mountains to the floor of the deepest ocean. Rocks are continually changing. Wind and water wear them down and carry bits of rock away; the tiny particles accumulate in a lake or ocean and harden into rock again. The oldest rock that has ever been found is more than 3.9 billion years old. The Earth itself is at least 4.5 billion years old, but rocks from the beginning of Earth’s history have changed so much from their original form that they have become new kinds of rock. By studying how rocks form and change, scientists have built an understanding of the Earth and its long history. Scientists study the Earth for many reasons: to find water to drink, or oil to run cars, or coal to heat homes; to know where to expect earthquakes or landslides or floods; and to try to understand our natural surroundings. The Earth is constantly changing—nothing on its surface is truly permanent. Rocks that are now on top of a mountain may have once been at the bottom of the ocean. In order to understand the world we live in, the dimension of time must be considered and the Earth’s history studied. In Earth’s history, time is measured in millions and billions of years. Scientists who study the Earth’s history use the geologic timescale. Nineteenth-century geologists and paleontologists believed that the Earth was very old, but they only had crude ways of estimating just how old. The assignment of ages of rocks in thousands, millions, and billions of years was made possible by the discovery of radioactivity. Today, scientists can use minerals that contain naturally occurring radioactive elements to calculate the numeric age of rocks in years.

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The basic unit of each chemical element is the atom. An atom consists of a central nucleus, which contains protons and neutrons, surrounded by a cloud of electrons. Isotopes of an element are atoms that differ from one another only in the number of neutrons in the nucleus. A radioactive isotope (called the “parent”) of one chemical element naturally converts to a stable isotope (called the “daughter”) of another chemical element by undergoing changes in the nucleus. The change from parent to daughter isotope happens at a constant rate called the half-life. The half-life of a radioactive isotope is the length of time required for exactly one-half of the parent atoms to decay to daughter atoms. Each radioactive isotope has its own unique half-life. Precise laboratory measurements of the number of remaining atoms of the parent and the number of atoms of the new daughter produced are used to compute the age of the rock. For dating geologic materials, four parent/daughter decay series are especially useful: carbon to nitrogen, potassium to argon, rubidium to strontium, and uranium to lead. Age determinations using radioactive isotopes are subject to relatively small errors in measurement—but errors that look small can mean many—even millions—of years. Isotope techniques are used to measure the time at which a particular mineral within a rock was formed. It is possible to assign numeric

Isotopes Commonly Used to Date Rocks Parent Isotope

Daughter Isotope

Half-life of Parent (years)

Useful Range (years)

Carbon 14

Nitrogen 14

5,730

100–30,000

Potassium 40

Argon 40

1.3 billion

100,000–4.5 billion

Rubidium 87

Strontium 87

47 billion

10 million–4.5 billion

Uranium 238

Lead 206

4.5 billion


Uranium 235

Lead 207

710 million



ages to the geologic timescale; a rock that can be dated isotopically is found together with rocks that can be assigned relative ages because of their fossils. Many samples, usually from several different places, must be studied before assigning a numeric age to a boundary on the geologic timescale. As dating techniques become more technologically refined, dating will continue to become more accurate. Knowing what kinds of rocks are found below the soil can also help scientists make informed judgments about the Earth’s vast array of natural resources. The layers of rock—an area of study called stratigraphy—are like the pages in a history book; they have many diverse stories to tell. Understanding this history requires a good deal of detective work: gathering the evidence and making comparisons. For example, the

Footprints in Stone Dinosaur tracks are visible in many places on public land (land administered by the federal government) in states such as Utah and Wyoming. Some are only a few inches long, and others—made by the giant plant-eating sauropods—are the size of automobile tires. Fivetoed primitive reptiles and amphibians made other tracks. Tracks and other evidence of an animal’s activity are a special kind of fossil called a “trace fossil.” Parts of the body, such as bones and teeth, are “body fossils.” Dinosaur tracks were formed when animals stepped in soft mud or sand millions of years ago, and more mud or sand gently covered the tracks soon after they were made. Over time, more sediments covered them, and the sediments turned to rock. When erosion wears some of the rock away, the tracks may be seen as impressions that seem as fresh as if they were made yesterday. If the tracks were made in a layer of very soft sediment, that layer may have disappeared, and only the hardened sediments that filled the tracks remain. These look like raised footprints when they are turned upside down. (Source: U.S. Bureau of Land Management)

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The major groups of animals and plants have originated at different times in Earth’s history.

istribution of fossils (skeletons, shells, leaf impressions, footprints, d and dinosaur eggs) in rocks of a certain age tells us something about the ancient distribution of lands and seas on the Earth’s surface. Through the study of fossils, it is possible to piece together what conditions existed on the Earth during a particular geologic time. For example, if fossils from fish are found in rock formations, this provides evidence that an ocean existed there at one time. As an illustration, the remains of coral and clamshells found in the very old limestone in parts of Pennsylvania and New York indicate that a shallow sea once covered this region. Certain plants may suggest specific climates; other plant and dinosaur fossils present in a rock formation may indicate the presence of oil or coal. Ocean fossils can also give clues as to what the climate was like during a period of geologic time. For instance, if the fossil is coral, it tells the paleogeologist (a geologist who studies ancient life and rock forms) that the water at that time was warm, tropical salt water—similar to the


seas around Florida and the Bahamas today. Important factors such as depth, temperature, currents, and salinity are revealed by sea life fossils and allow scientists to reconstruct the environments and resources of the past. Rocks also offer clues to climate in other ways. For example, areas on mountains where the bare rock is striated (scratched in parallel lines) tell geologists that glaciers flowed over this area at one time. The shape of canyons can also be indicative of past glaciation. When glaciers flow down canyons, they grind away the rock of the canyon walls and produce U-shaped valleys. When canyons exhibit the characteristic U shape, contain rock striations, and contain deposits of

How to Help Preserve Our Fossil Heritage By only looking at them and not touching them, you can help preserve dinosaur tracks. Follow these rules: • Admire the tracks, but do not walk directly on them or ride bikes or drive vehicles over them. • Take photographs or make drawings. • Measure the tracks, but do not draw on them. • Never try to remove the tracks or take pieces of them. • Never try to make a replica by putting anything in or on the tracks. • If you find rocks or other fossils you think may be new discoveries, record their location and pass your information on to your local Bureau of Land Management (BLM) office. Specialists can then document your find, make scientific observations, and take photographs. Computers and special cameras can make threedimensional digital images that will last forever, even after the tracks have eroded away. (Source: U.S. Bureau of Land Management)

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Glacial valleys have a characteristic U-shape, formed by the ice eroding the side walls of the canyon as the glacier travels downhill. Glaciers leave boulders behind—known as erratics—when the ice melts, as seen on the left side of the bottom of the U. Glacial valleys help climatologists determine the past climate of the region. (Photo by Nature’s Images)

big boulders (called erratics) on the sides and the base of the canyon, geologists can deduce that the climate in the area was cold enough at one time to support glaciers.

Resources From Ancient Lakes One huge lake that existed in ancient times—called Lake Bonneville— has enabled paleogeologists to determine the past climate of the western United States and also to recover and utilize various resources associated with it. Lake Bonneville was a large, ancient lake that existed from about 32,000 to 14,000 years ago. It occupied the lowest, closed depression in the eastern Great Basin and at its largest extent covered


about 20,000 square miles (51,800 sq. km) of western Utah and smaller portions of eastern Nevada and southern Idaho. At its largest, Lake Bonneville was about 325 miles (523 km) long, 135 miles (217 km) wide, and had a maximum depth of over 1,000 feet (305 m). It contained many islands that are the present-day mountain ranges of western Utah. Its relatively fresh water was derived from direct precipitation, rivers, streams, and water from melting glaciers. During the time of Lake Bonneville, the climate was wetter and colder than now. Lake Bonneville left three major shorelines. The shorelines can be seen as terraces or benches along many mountains in western Utah. Each separate shoreline represents an extended period during which the lake stood at that elevation. By studying the fossil record, scientists have determined that fish lived in Lake Bonneville; amphibians, waterfowl, and other birds inhabited its marshes; and animals such as buffaloes, horses, bears, rodents, deer, camels, bighorn sheep, musk oxen, and woolly mammoths roamed its shores. Archaeologists have set the arrival of humans in the Lake Bonneville Basin at about 10,000 years ago. For a long period of its history, Lake Bonneville was a terminal lake with no rivers draining from it. The lowest outlet for Lake Bonneville, Red Rock Pass in Idaho, had an elevation of about 5,090 feet (1,551 m). Approximately 16,800 years ago, the lake rose to the elevation of Red Rock Pass in the Sawtooth Mountains near present-day Pocatello, Idaho, and began to flow northward into the Snake River drainage. The flow of water through the pass began a rapid down-cutting process that caused a catastrophic flood. Researchers believe that the flood probably lasted less than a year. During this year, floodwaters cut through the soil and rocks and lowered the outlet elevation about 375 feet (114 m). The lake stabilized and the new shoreline formed during the next 600 years. The Great Salt Lake is the only remnant today of Lake Bonneville. Three important land resources used today from this ancient lake are sand, gravel, and salt. Sand and gravel are mined from the deltas

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FPO Figure 19b

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(a) The shoreline of ancient Lake Bonneville can be seen as a horizontal line halfway up the mountain. This shoreline created a “bench” that many homeowners build their houses on today. (b) Rivers deposited huge amounts of sand and gravel into the ancient Lake Bonneville. The heaviest materials—gravels—were deposited first, followed by the finer particles—such as sand. Sand and gravel are natural resources that can be mined and used in the production of cement, road base, and landscaping materials. (c) Large equipment can be seen mining the immense deposits in the delta, while above—on the Lake Bonneville shoreline—several homes have been built. (d) Gravel is extracted from the delta material, then carried by conveyor belt to be loaded onto trucks for delivery. (Photos by Nature’s Images)


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(a) The Bonneville Salt Flats are a remnant of ancient Lake Bonneville. This area is one of the flattest places in the world. (b) The Salt Flats are a popular destination for speed racing. Gary Gabelich set the current land speed record of 622.407 miles per hour (1,001.67 km per hour) on the raceway in 1970. Hundreds of competitors descend on the Salt Flats each year during the National Speed Trials, seen here in 2003. (Bureau of Land Management, photos by Kelly Rigby)

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that formed at the mouths of canyons where rivers entered the ancient lake. These resources are mined today and used in the production of concrete for construction and for road base. The Bonneville Salt Flats are another remnant of the ancient lake. They are located west of the Great Salt Lake, about 115 miles (185 km) west of Salt Lake City, Utah. The flats are a broad, salt-covered lake bed and one of the flattest areas on Earth. They were formed during the final evaporative stages of ancient Lake Bonneville. The salt flats are the site of high-speed car-racing events. Its racetrack was the location for the land speed records set during the 1950s, 1960s, and 1970s. In 1970, Gary Gabolich of the United States piloted the rocket-powered Blue Flame racer to a speed of 622.407 miles per hour (1,001.621 km/hr), a Bonneville Salt Flats speed record that still stands today. In the past 30 years, there has been an apparent deterioration of the racing surface. This has become a controversial issue involving the U.S. Bureau of Land Management, those who race on the salt flats, and a company that produces potassium chloride salt and magnesium chloride (brine) from salt-flat brine. Studies are underway to determine why the salt is disappearing, if the loss can be stopped, and if the salt can be replaced. Many companies mine the salt from the deposits near the present-day Great Salt Lake to be used for many applications, such as consumption, to melt ice on snowy roads in the winter, and to produce soft water in many homes.

Red Horn Coral Red horn coral is a unique fossil found high on the mountaintops of the Uinta Mountains in present-day Utah. This fossil is popular today in custom-made jewelry—another type of valuable resource. Red horn coral is a very rare fossilized coral. It was created 65 million to 85 million years ago. During the mid-to-late Cretaceous period, 65 million to 135 million years ago, the Earth’s volcanic activity forced new ridge systems to rise high above the old ocean depths in the Pacific Ocean and lifted neighboring ocean floors with them.


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(a) Red Horn Coral is a rare mineral found in this remote site on a mountaintop near Woodland, Utah, in the Uinta Mountains. This area was once in a tropical biome under an ocean, which allowed the coral to form. (b) Red horn coral is found in small formations that look like “horns.” It is often crusted with deposits from the ancient ocean, but when it is polished it reveals the beautiful coral inside. (c) This piece of red horn coral measures two inches (5 cm) in size and is set in a beautiful necklace created by a Navajo silversmith. Each piece of coral has a unique design within it—ranging from starburst shapes to clusters of curious bubbles. (d) A polished piece of natural red horn coral is surrounded by custom-made coral pendants. (Photos by Nature’s Images)

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Not only was the ocean floor crust rising, but because of all the volcanic activity, massive amounts of carbon dioxide were released into the atmosphere, causing additional warming. The effect was dramatic—the ice caps melted, and the oceans were 656 feet (200 m) higher than they are today. The sea progressed inland up through the Midwestern parts of the United States almost into Canada, while much of Europe was under water, as well. The sea covered much of the Rocky Mountains, and because of the warming of the Earth’s climate, it made an excellent habitat for the coral to live in. The fossilized coral is a beautiful gemstone used in jewelry today. It ranges in color from pinks to deep reds and commonly has a starburst ray pattern running from the center to the edges, like spokes on a wheel. The coral gets its name from the horn-shaped formations it grew in.

Petroglyphs—Stories of the Past Written on the Landscape Archaeologists dig for the remains of ancient civilizations and are able to put the pieces of the past together to understand those who lived in a place hundreds, even thousands, of years ago. Artifacts are objects that archaeologists dig for. These are objects left behind when a group of people either left an area or died out. These objects can be pottery, utensils, arrowheads, stones, feathers, timbers used in construction, and even corncobs. They also include buildings made of mud, rock, or other materials. The types of artifacts found can serve as clues to the past. For example, living quarters would have artifacts such as pots, dishes, plates, utensils, and midden (garbage) heaps. Other areas might have arrowheads and remnants of weaponry, signaling that the group of people living there hunted for their food and/or needed to defend themselves. If old plows are found, this tells archaeologists that a previous culture was agricultural and so grew their food on the land. Some of the ancient Native American cultures painted beautiful petroglyphs on the smooth stone rocks of the American Southwest.


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(a) Ancient Native American civilizations left behind petroglyphs on stone walls throughout the American Southwest. These drawings are valuable resources in learning about early Native American culture. (b) Native Americans utilized the landscape and land’s resources to build their dwellings in natural alcoves and high on cliffs for protection from the weather and other dangers. (Photos courtesy of the Bureau of Land Management)

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These cryptic drawings show information such as what animals inhabited the area, what the people ate, what they did for jobs, and they even give archaeologists a glimpse into the traditions, culture, and religious beliefs of the people. Artifacts in the United States have been found over the centuries and have provided much helpful information to archaeologists and historians. For example, historians have learned about the cultures of specific groups in the United States, such as the Native American tribes,

Archaeological Remote Sensing Remote sensing is a science where information is collected about a place by studying aerial photos (photos taken from a plane) and satellite imagery (pictures taken from space). By studying the landscape with remote sensing tools, archaeologists can learn where to dig for past ruins. Remote sensing cameras are designed to detect different wavelengths of electromagnetic radiation from the sun—all the way from the shortest wavelengths (such as ultraviolet and X-rays) to the longest wavelengths (such as infrared, radio waves, and microwaves). Different remote sensing sensors (“cameras”) are able to see in specific wavelength regions. For example, sensors that detect infrared radiation are used when studying vegetation because trees, shrubs, and grasses reflect infrared light; and even though the human eye can’t see the infrared wavelengths, the sensors can. Therefore, since sand, cultivated soil, vegetation, and all kinds of rocks each have distinctive temperatures and emit heat at different rates, sensors can “see” things beyond ordinary vision or cameras. Remote sensing can help archaeologists locate ancient ruins because they can detect irrigation ditches filled with sediment, which hold more moisture and have a different temperature than the surrounding soil. The ground above a buried stone wall may be slightly hotter than the surrounding terrain because the stone absorbs more heat. Radar waves can actually penetrate the ground to “see” what is under the soil.


pilgrims, mountain men, explorers, hunters, trappers, pioneers, and prospectors—who all used the land in different ways. They also discovered who different cultures traded with. For example, some Native American tribes traded with other native tribes from South America. Macaw feathers have been found in Anasazi (an ancient Native America tribe that lived 1,000 years ago in the American Southwest) ruins. This informs archaeologists that these ancient people had made contact with faraway tribes (a macaw is a parrot only found in South America).

Remote sensing can also be a “discovery” technique, since the computer can be programmed to look for distinctive “signatures” of energy emitted by a known site or feature in areas where surveys have not been conducted. Such signatures serve as recognition features or fingerprints. Such characteristics as elevation, distance from water, distance between sites or cities, corridors, and transportation routes can help to predict the location of potential archaeological sites. Beaming radar pulses into the ground and measuring the echo is a good way of finding buried artifacts in arid regions. Man-made objects tend to reflect the microwaves, providing a “picture” of what is underground without disturbing the site. There are several examples of how remote sensing has been used to make archaeological discoveries: • The Maya causeway was detected through emissions of infrared radiation at a different wavelength from surrounding vegetation. • A laser device called lidar has been used to detect eroded footpaths that still affect the topography in many parts of the world. • In 1982, radar from the space shuttle penetrated the sand of the Sudanese desert and revealed ancient watercourses.

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Each of these groups has helped paint the canvas of American history as we know it today. Archaeology also serves to refine history—the more archaeologists learn, the better we understand the past.

Land Use and Development Throughout History An early development of land use was converting wild lands into agricultural lands in order to grow food and support populations. Agriculture originated about 10,000 B.C. and marks the point where human beings began to take control of their environment. They replaced the natural vegetation with crops so that they could have a dependable food supply in order to survive. Up until that time, people were hunter-gatherers, who had to spend most of their time gathering wild seeds and fruit and hunting animals. Fortunately, people began to realize that crops could be planted and grown and that animals could be domesticated (tamed) to assist in plowing. Through studying the land, archaeologists think agriculture may also have started for social reasons—so that people could harvest and trade with each other. Farming—and taming the landscape—began in at least five different places. Turkey and the Middle East began cultivating wheat, barley, peas, and lentils. People in these areas also began raising sheep and goats. In Southeast Asia, people began to grow vegetables and raise pigs and chickens. In South America, separate agricultural development began in both the Andes and the Amazon regions. Northern China and West Africa also began their own development of agriculture. The taming of the landscape occurred through the invention of plowing and irrigation. Although the United States uses sophisticated, technological means of farming today, people in many countries in the world still use the old methods of plowing and irrigation developed by these earliest farmers. The advent of agriculture changed the structure of civilization so that people could use the land in other ways. During the days of the hunter-gatherer lifestyle, the land could only support a limited number of people. But once crops could be grown, harvested, and stored, that


changed. The advantages of beginning an agricultural society were that it could support a larger population and allowed for better survival since excess food could be stored over the winter. It also allowed people to stay in one place and to not have to move around to gather food. It promoted commerce in civilization (business and trading) by enabling people to sell goods for a profit. This began the early stages of modernizing the world. It is important to understand that all these major centers of agriculture began along major river systems. Without rivers like the Nile, Indus, Huang, Tigris, and Euphrates to provide a consistent source of silt (a natural fertilizer) from yearly floods and water for irrigating crops, this development could not have taken place. As farming became more sophisticated, fewer people needed to be farmers. This led to scientific inventions and industrial and cultural advances. It also made possible the developments in architecture and the building of cities. It allowed other people to become scientists and study astronomy, which began the development of navigational skills later used to explore the world. Fewer people farming enabled a more diverse use of the land’s resources. Later, the Industrial Revolution in the late eighteenth century caused the rapid growth of towns and cities and forced agriculture into its own sector, allowing land to be used for multiple applications. For example, it enabled the land to be used for grazing animals, mining, exploration, transportation, and recreation.

The Opening of the American West When the 13 colonies were formed in the early history of the United States, they covered only a small portion of all the land that comprises the United States today. The western part of the country was largely unexplored by immigrants who had come to live in the United States. Many explorers began heading out west to see what land lay beyond the already established settlements. As explorers began to get a feel for how much land lay to the west, it became important to begin the task of surveying and mapping the uncharted lands and recording the existence of the land’s natural resources along the way.

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The trail of the Lewis and Clark Expedition is shown above. The purpose of the expedition was to chart new territories in the West and make scientific observations about the land’s resources.

Two of the most well-known explorers were Meriwether Lewis and William Clark. Their expedition, referred to as the Voyage of Discovery, began in 1804 when Thomas Jefferson sent them to find the fabled River of the West. From the time of Columbus, explorers and statesmen had dreamed of a Northwest Passage—an all-water route connecting the trade routes of the Pacific to the Old World of the Atlantic. The Lewis and Clark Expedition was the first of many government surveys of natural resources in the American West. They documented and charted in detail the vast and increasingly rugged terrain they encountered on their journey. In addition to charting their path, Lewis and Clark discovered, studied, and wrote in their journals about many natural resources observed on their trek, such as the volcanoes of the Cascade Mountains, lava flows from the Columbia Plateau, the Cascade Range, the Williamette


Lowland, the Blue Mountains, river channels carved by the great “Missoula Floods,” the Wallula Gap, the Columbia River, and the Pacific Mountain System. They charted the Missouri River and its tributaries during the early 1800s. They also offered some of the first modern interpretations of numerous geologic features, as well as observing many different species of birds and mammals. In the years that followed Lewis and Clark’s expedition, many surveys were conducted by the government and the railroads in response to the increasing resource and transportation needs of the United States. As the demand for resources grew, science became an increasingly important part of the expeditions. Four surveys became known as the “Four Great Surveys of the West.” These surveys were led by Clarence King; Ferdinand V. Hayden, M.D.; Major John Wesley Powell; and Lieutenant George Wheeler. Powell and his expedition was much like Lewis and Clark and their Voyage of Discovery. Like Lewis and Clark, Powell had military experience. Lewis and Clark explored unknown parts of the Louisiana Purchase and the Rocky Mountains. Powell explored the unknown canyon lands in the American Southwest. Here, Powell and his crew took boats through the Grand Canyon to record what they saw. Hayden and King were involved in the surveys of Nebraska, Wyoming, Colorado, the Rocky Mountains, and Yellowstone, mapping the territories of the United States. Wheeler was sent to explore and map the United States west of the 100th meridian at a scale of 8 miles (13 km) to the inch. The efforts of these surveyors helped to compile an accurate picture of the American West and its vast natural resources, such as minerals, water supplies, vegetation, topography, soil types, and wildlife habitats.

The Dust Bowl of the 1930s and the Lessons Learned The worst agriculture-related loss in American history occurred during the early 1900s. Because of World War I, there were significant wheat shortages, which caused the price of wheat to rise dramatically. At that

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time, wheat was very profitable—farmers could make a lot of money selling it. At the same time, the U.S. government encouraged farmers to produce more wheat, so farmers on the fragile southern Great Plains plowed up the natural grass cover that had protected the soil for centuries so that they could plant winter wheat. The Great Plains extend eastward from the Rocky Mountains across the western parts of North and South Dakota, Nebraska, Kansas, Oklahoma, and Texas. Soon, the wheat crops exhausted the topsoil. In addition, overgrazing by cattle and sheep herds stripped the western plains of their protective grass cover. Then the area was devastated by a severe drought from 1934 to 1937. Because the land had been plowed up and the delicate, stabilizing root systems formed by the grass removed, the large plowed areas had no grass root system to keep the soil anchored in place. A lot of the soil dried out, turned to dust, and blew away. The area was covered with horrible dust storms and sandstorms that buried roads, houses, towns, and fields. Clouds of dust were blown as far away as Chicago, New York, and Washington, D.C. It turned the skies dark. Eventually, the soil blew out over the Atlantic Ocean, where it was lost forever. This area was called the Dust Bowl. It covered an area 500 miles (805 km) by 300 miles (483 km) in size—almost 100 million acres of land. The drought and topsoil loss lasted until 1938. Many people who lived in the Dust Bowl states abandoned their farms and moved away. The Dust Bowl exodus was the largest migration in American history. By 1940, 2.5 million people had moved out of the Plains states. In response to this disaster, the federal government created the Soil Erosion Service and the Civilian Conservation Corps (CCC) to recover the land. Many conservation practices were begun, such as replanting the grass, planting tree windbreaks (called shelter belts), crop rotation, contour plowing, and strip plowing. They also showed farmers new scientific agricultural methods to help them protect the fragile grassland ecosystem of the southern Plains. Today, decades of conservation methods have begun to pay off. The erosion rate by water has decreased, farmers are consistently using


c onservation practices, and more farmland is being enrolled in the federal government’s Conservation Reserve Program every year.

The 1935 Soil Conservation Act Hugh Hammond Bennett, a soil scientist and member of President Franklin D. Roosevelt’s administration, realized that every American’s future was tied to the plight of the Dust Bowl farmers—it affected the entire country, not just the Great Plains. He wanted to preserve the soil by reforming farming practices. He became known as “The Father of Soil Conservation.” In 1933, he became the first director of the newly formed Soil Erosion Service, whose job it was to fight against erosion and improve farming methods. Through his work and efforts, the Soil Conservation Act of 1935 was passed. Its focus was on improving farming techniques. The Soil Conservation Act established the Soil Conservation Service (SCS). The chief purpose of this agency was to deal with issues of soil erosion. Bennett was largely responsible for the acceptance of workable soil conservation methods. He played a major role in converting a large part of the Great Plains back to grasslands. In its early years, the Soil Conservation Service conducted soil surveys of land around the United States. They also looked at other conservation problems, such as soil salinity control. The SCS currently publishes maps showing areas of soil erosion and is also involved in the scientific research of pesticides. Without the help of the SCS, we probably would not have come as far as we have today in rehabilitating and taking care of the land. Overgrazing and Desertification Certain land management practices can degrade the land. One area of environmental concern is the effect of overgrazing on rangeland. Ranchers must take care not to let their cattle and sheep overgraze their rangeland. Overgrazing uses up all the nutrients in the soil. Having too many animals grazing and roaming in a confined area can trample the ground, which squeezes the soil particles together so that there is no

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open air space. This keeps nutrients and water from being able to move around inside the soil to keep it fertile. In the United States, about 40% of the land is considered rangeland. If conservation measures are not practiced, overgrazing by livestock can alter plant communities by removing some species and allowing invasive species and noxious weeds to take over. If livestock are allowed to overgraze and destroy the native grasses that grow in the area, leaving the ground bare, an invader species—such as cheatgrass—can take over an area and outcompete the native grass. The invader species may disturb the natural balance of an area, making it impossible for the native vegetation to compete and survive. In addition, the invader species may not be edible as a grazing staple, thereby removing a significant food source from the animals. This is one reason why ranchers have to take great care in not letting their herds overgraze the land. Upsetting this balance has been a significant problem in the western United States for many years. This often occurs in the Southwest, where dry conditions persist and drought is common. Once a delicate balance is upset, it is very difficult to reverse it through long-term reclamation efforts. Scientists estimate that in the United States, 30% of the erosion is due to natural forces of nature and 70% is a result of human impact. Oftentimes, when people use the land for farming and overgrazing takes place, the protective covering of natural vegetation is destroyed and the erosion process speeds up. In fact, studies have shown that human-caused erosion played a big part in the downfall of many early civilizations. Poor land management practices degraded the soil to the point where it was no longer productive enough to support the population living in the area. In many areas of the world, forests have been cleared and converted to rangeland/pasture, which has resulted in a significant loss of biodiversity and wildlife habitat. In some places, it has changed the structure and function of ecosystems. When the ecological balance becomes severely disrupted, a process called desertification can take place, making the area uninhabitable for plants, animals, and even people. When the health of the land degrades


Roland Burchard (standing) and Claude Birdseye (taking notes at right) explore the Colorado River in this photograph from 1923. Birdseye was the first Chief Topographic Engineer of the USGS (1919–1929). He headed a USGS expedition through the Grand Canyon in 1923 to acquire information on the hydrology, topography, and geology of the Colorado River. (Photo courtesy of the USGS)

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to this point, vegetation no longer grows; then when the ground is bare, it is highly susceptible to erosion from wind and water, further reducing the health of the land. Desertification is a problem especially in the semiarid and arid areas of the world.

Trends in Today’s Land Use Over the past 150 years, the most significant trends in land use have been a function of the exponential growth in human populations. Along with growing populations comes the construction of residential homes, commercial buildings, factories and other industry, and highways. As these types of land use increase, they take their toll on the environment: More resources are necessary, pollution becomes an issue, water quality can be degraded, and precious natural resources may be destroyed and lost forever. Urban sprawl, combined with technological advancement, has led to the widespread transformation of natural ecosystems into those dominated and heavily managed by human beings. Overpopulation has resulted in overuse of the land’s resources, including overfishing; overgrazing; abandoned mine and quarry dangers; cleared forests from logging activities; waste treatment and disposal issues; pollution leading to the greenhouse effect and acid rain; wildfires; and contamination of water, air, and soils. The potential impact of these activities on the Earth’s biological and geochemical systems is an area of concern for scientists and conservationists alike. Issues of concern include biosphere-atmosphere interactions, global climate change, soil productivity, preservation of biodiversity, sustainable development, loss of wildlife habitat, increased energy consumption, and agricultural productivity. These issues, which focus on why healthy management of the land’s resources is so important, will be discussed in detail in Chapter 7.

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and is the foundation of many of the Earth’s major resources that humans enjoy today. Understanding their roles and distribution is necessary in order to utilize them. Conservation is also important—for if resources are mismanaged, they will not be available for use. There are two types of resources: renewable and nonrenewable. This chapter focuses on the different resources found on the Earth’s land, such as agricultural, botanical, soil, desert, glacial, rangeland, wildlife, wetland, energy and minerals, and grasslands.

Renewable vs. Nonrenewable Resources Natural resources are the raw materials that humans use for housing, clothing, transportation, heating, and cooking. They include the air we breathe, the water we drink, the land we farm, and the space we use for living and recreation. They are all the things we use in our physical environment to meet our needs and wants.

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Nonrenewable resources exist in fixed amounts: once they are used up, they are gone forever. For example, fossil fuels, copper, and iron are formed through natural processes that take millions of years. Because they take so many years to form, these resources are considered nonrenewable—the term renewable means that a resource can be replaced within one generation of a human’s lifetime (about 20 to 30 years). Renewable resources are materials that can be replenished through natural and/or human processes. For example, if trees are harvested, those trees will die; but if new seeds are planted, other trees will grow in their place in a relatively short period of time. All resources need to be carefully managed; nonrenewable resources need to be managed so that they are available as long as necessary, and renewable ones so that they can keep regenerating. For example, grass is a renewable resource, but if it becomes overgrazed to the point where the soil cannot support plant life, the area will suffer from desertification, and grass will no longer grow there. Humans must also be aware of a concept called sustainable yield. This means that a resource cannot be used in greater quantities than the resource can naturally supply. When resources are used beyond their sustainable yield, then the resource will become extinct. For example, if an animal is hunted to the point where only one remained, that would exceed its sustainable yield, and when that last one died, the species would become extinct. The number of people using a resource and the amount each person uses are important in determining how quickly resources get used. The sustainable yield of any resource varies from region to region and requires management practices specifically suited to it. People’s lifestyles are determined by the availability, distribution, and use of natural resources. An advantage of using a renewable resource in a sustainable way is that it can last forever. In order to do this, however, it needs to be managed and controlled.


Agricultural Resources When looking at agricultural resources, such as soil, agriculture, and livestock resources, only soil might be originally thought of as a nonrenewable resource. But agricultural resources are not as clear-cut as other types of resources, such as energy. Agricultural resources involve life, and life is a very fragile and complex thing. All elements of life are interwoven. In other words, in the complex system of life (interactions between different components), if one element is affected, the entire cycle is affected. If one component stops working the way it should, the entire system is jeopardized, and until that one component is managed correctly, the system fails or is unproductive. America saw this happen with the Dust Bowl—the soil system was damaged, which triggered a chain reaction, making the land unfarmable. Using a soil too much over a long period of time for a single crop can rob the soil of the specific nutrients needed by that crop. If the nutrient is used up in the soil, then any crop requiring that nutrient will be unable to grow. The delicate balance is affected, and that crop can become nonrenewable. Another form of nonrenewability is when an aggressive plant or weed infests an area. It can crowd out a native plant by choking it off or by using vital nutrients in the soil that the native plant needs so that the native plant cannot survive. Whatever the reason, if the native plant is removed and the invasive plant takes over, the native plant has become nonrenewable in that area as long as those conditions exist. There are many agricultural crops produced in the United States. Different commodities (items) are produced in different parts of the country. The United States is fortunate to have a large variety of crops that can be grown, such as fruits, vegetables, grains, hay, cotton, sugar, beans, peas, lentils, flowers, and landscaping plants and trees. While many people may think that these resources are automatically renewable, that is not necessarily so. Their availability and productivity is part of a complex system that must be delicately balanced.

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Urban sprawl has encroached on many agricultural lands. These photographs show urban development in Salt Lake City at three different time periods: (a) 1958; (b) 1977; and (c) 1997. (Photos by Nature’s Images)


Botanical Resources Plants are a highly valuable resource. They are the basis of a healthy ecosystem and perform important functions, such as purifying the air and water. Humans, and other life, depend on the oxygen that is given off as a by-product from photosynthesis in plants. Plants are also important in the water cycle—more than 90% of the water that is taken in through a plant’s roots is eventually released back to the atmosphere in a process called transpiration. Plants provide the basis of most food webs on Earth. They provide protection and shelter by providing wood to construct homes with and cotton to make clothing. In addition, plants provide shelter and habitat for many other animals as well. For example, a single tree in the rain forest can be a home to more than 1,000 different insect species. Plants are also used in medicines. From traditional herbal remedies to components of prescription drugs, plants play a vital role each day in our health and well-being. Plants provide energy to make our lives more convenient. (Coal, for example, was formed from decayed vegetation millions of years ago.) In addition to this source of energy, we have the technology today to produce biofuels from corn and other biomass. As technology improves, ethanol—a fuel produced from corn—may someday replace the fossil fuels we currently rely so heavily on. Many industrial products are made from plants. For example, plants provide the ingredients for commodities such as soap, glue, pencil erasers, bath powder, cosmetics, body lotions, nail polish remover, plastics, and high-quality industrial lubricants. Plants also have an intangible value. Although it cannot be specifically measured, plants do provide an important aesthetic value to life. Whether used as landscaping, ornamental decorations, flower arrangements, or many other forms, plants play an important role in our pleasure as well as cultural traditions. For example, what would Christmas be without evergreen trees, or weddings without flowers? Plants provide some of the most critical food staples. The most common and important plants in the world are grasses. Not only do they provide food for most domesticated and wild animals, they supply

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much of the world’s sugar in the form of sugarcane. All the cereal crops, such as corn, wheat, oats, rye, barley, rice, and millet are grasses. Although it may seem that plants are renewable, that may not be the case. For example, if an aggressive plant or weed infests an area, it can crowd out native plants. If an invasive plant takes over, the native plants can become nonrenewable in that area as long as those conditions persist. A plant’s availability and productivity is part of a complex system that must remain delicately balanced in order to function.

Soil Resources Soil resources are related to factors such as fertility, fragility, and erosion. Land use and land management has a tremendous impact on the health of the soil. Because soil is a nonrenewable resource (it takes longer than a generation to form), protecting the soil quality is very important. Soil is important in many ways: it provides a home to organisms, it decomposes wastes, it acts as a filter of water and contaminants, it is used to grow crops in, and it exchanges gases, which keep the resource cycles going. Because there is a limited amount of soil available, it must be properly cared for. There are several ways that farmers and ranchers take care of this valuable resource—many of them learned after the Dust Bowl experience. Farmers can reduce the amount of tilling (disturbing and overturning the soil by plowing) they do on the land. They can practice farming conservation by rotating crops, using buffer strips, keeping fields fallow, using compost in the soil, terracing steep land, strip cropping, contour farming, and by not overgrazing livestock. In crop rotation, the farmer grows a series of different crops, one after the other, in the same field. This reduces the threat from pests and disease associated with a particular crop and helps the soil stay fertile and healthy. Leaving land fallow is also helpful. Fallow land is land left unplanted so it can recover nutrients that may have been lost from a previous crop. It gives the soil time to rest. Buffer strips, contour farming, and terracing


are all conservation techniques the farmer can use. Composting can be done to add additional nutrients to the soil (called soil augmentation). Compost is a mixture that is made up of decayed organic matter and is used for fertilizing and conditioning the land. Ranchers can take care not to overgraze their land, which uses up all the nutrients in the soil. Too many cattle can trample an area, which squeezes the soil particles together so that there is no open air space. This keeps nutrients and water from being able to move around inside the soil to keep it fertile. Farmers and ranchers must also control rainfall runoff. Runoff water dissolves nutrients and removes them from the pasture as it flows over the soil surface. Soil erosion transports nutrients away. It can also remove contaminants, such as pesticides, that are attached to soil particles, which are then redeposited in other places, like rivers or lakes, which results in pollution.

Desert Resources Approximately one-third of the Earth’s land surface is desert—arid land with little rainfall that supports only sparse vegetation and a limited population of people and animals. Arid regions are called deserts because they are dry—they may be hot, or they may be cold. They may be regions of sand or vast areas of rock and gravel with occasional scattered plants. Deserts contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for archaeological artifacts and fossils to be preserved for discovery and study. Some mineral deposits are formed, improved, or preserved by geologic processes that occur in arid lands because of the climate in the area. Groundwater leaches ore minerals and re-deposits them in zones near the water table. This leaching process concentrates these minerals as ore that can be mined. According to the U.S. Geological Survey, of the 15 major types of mineral deposits in the Western Hemisphere formed by the action of groundwater, 13 occur in deserts.

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Evaporation in arid lands enriches mineral accumulation in lakes. Playas are often sources of mineral deposits formed by evaporation. Water evaporating in closed basins precipitates minerals such as gypsum, salts (including sodium nitrate and sodium chloride), and borates. The minerals formed in these evaporite deposits are determined by the composition and temperature of the saline waters at the time of deposition. Significant evaporite resources occur in the Great Basin Desert of the United States. Borax—a mineral deposit—was mined in Death Valley and hauled to railroads by 20-mule-team wagons. Boron, from borax and borate evaporates, is an essential ingredient in the manufacture of glass, ceramics, enamel, agricultural chemicals, water softeners, and pharmaceuticals. Borates are mined from evaporite deposits at Searles Lake, California, and other desert locations. According to the U.S. Geological Survey, the total value of chemicals that have been produced from Searles Lake exceeds $1 billion. The Atacama Desert of South America is unique among the deserts of the world in its great abundance of saline minerals. Sodium nitrate has been mined for explosives and fertilizer in the Atacama since the middle of the nineteenth century. Nearly 3 million metric tons were mined for use during World War I. Valuable minerals located in arid lands occur in many locations worldwide. For example, they include copper in the United States, Chile, Peru, and Iran; iron and lead-zinc ore in Australia; chromite in Turkey; and gold, silver, and uranium deposits in Australia and the United States. Nonmetallic mineral resources and rocks such as beryllium, mica, lithium, clays, pumice, and scoria also occur in arid regions. Sodium carbonate, sulfate, borate, nitrate, lithium, bromine, iodine, calcium, and strontium compounds come from sediments and nearsurface brines formed by evaporation of inland bodies of water, often during geologically recent times. The Green River Formation of Colorado, Wyoming, and Utah contains alluvial fan deposits and playa evaporates created in a huge lake whose level fluctuated for millions of years. Economically significant


deposits of trona, a major source of sodium compounds, and thick layers of oil shale are created in arid environments, as well. Some of the more productive petroleum areas on Earth are found in arid and semiarid regions of Africa and the Middle East, although the oil reservoirs were originally formed in shallow marine environments. The effects of recent climate change have placed these reservoirs in an arid environment.

Glacial Resources There are several resources associated with glaciers. When glaciers move down a canyon, they scrape the walls and floor of the canyon, eroding materials from them. These sediments become trapped in the ice and are carried along with the glacier. When a glacier melts and begins to retreat up-canyon, these unconsolidated sediments get deposited on the landscape. Unconsolidated sediments include rock material of all sizes—from boulders to gravel to sand, and everything in between. These sediments can be deposited along the outer margins of the glacier, at the end (toe) of the glacier, and through meltwater flowing out from channels carved beneath the glacier, called eskers. Occasionally, odd-shaped mounds of sediment are left behind, called drumlins. When the glaciers retreat, they leave these sediment deposits that can be utilized by humans as a resource. Glacial features, such as eskers and drumlins, have influenced settlement patterns around the world by providing agricultural land, good sites for housing development, and workable sand and gravel resources. In many areas, glaciers carved out the landscape and changed the drainage patterns to what they are today. For example, the city of Cincinnati is built on an abandoned floodplain overlooking the Ohio River. Glaciers have also left behind large deposits of sand and gravel that have contributed greatly to local economies. There are many quarries that use glacial deposits for the cement and construction industries. Glaciers left behind extremely fertile till plains that have led to incredibly productive agriculture, especially in the Midwestern regions of the United States. The unconsolidated materials are also beneficial to

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agriculture because they provide good drainage. Glacial till is the basis of many soil formations. Glacial deposits help forests by providing fertile soil that stands of pine, spruce, and hardwoods can grow in. This also supplies a valuable resource for timber markets as lumber companies produce building materials. One of the best resources glaciers have left behind are the sand and gravel deposits that are not quarried (mined), but are excellent aquifers that produce high quality groundwater.

Rangeland Resources Worldwide, 47% of the land area is considered rangeland, which includes grasslands, savannas, shrublands, deserts, alpine and Arctic tundra, coastal marshes, wet meadows, and many open forested areas. Rangelands comprise about 40% of the landmass of the United States. Rangelands provide valuable grazing lands for livestock and wildlife. They also serve as a source of high-quality water, clean air, and open spaces. Because of this, many people enjoy rangelands for recreational purposes. They also have economic value—the growing of agriculture, the extraction of minerals, and the development of communities. Rangelands are a type of land on which the vegetation is managed as a natural ecosystem. In North America, rangelands include the grasslands of the Great Plains stretching from the midwestern United States to Canada. Texas and Florida also have rangelands (savannas), and the western United States has an abundance of shrublands. While rangelands occur in every region of the continent, they are the dominant type of land in the arid and semiarid regions of the world. According to the Society for Range Management, 80% of the lands of the western United States are classified as rangelands, whereas only 7% of some areas near the East Coast are classified as rangelands. Rangelands provide many resources by serving multiple purposes. For example, they provide habitat for a wide array of game and nongame animal species, such as cattle, horses, sheep, and buffalo. Rangelands also provide habitat for a diverse and wide array of native plant species. They are well known as a source of high-quality water,


Rangelands in the western United States are used for many purposes. The rangelands in this photo are used for grazing cattle. Ranchers and land managers must be careful to monitor the condition of the rangeland to avoid overgrazing and the onset of desertification. (Courtesy of Bureau of Land Management)

clean air, and for their open spaces. Many people enjoy rangelands for their recreational values, such as hiking, camping, horseback riding, fishing, hunting, bird and wildlife watching, and other outdoor activities. Rangelands also provide the key renewable food sources for the livestock grazing business. Because of the diversity of goods and services derived from rangelands, it is important to maintain their health by managing them in a sustainable way. They provide the livelihoods for many communities and these communities depend on rangelands functioning as a renewable resource. This creates an extremely important role for resource managers. Rangeland resource managers must manage these lands for wildlife and fisheries habitats, recreation, watershed values, open space,

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and biofuels, in addition to the more traditional uses such as livestock grazing and food and fiber production. This multiple-use concept makes it very important that the right decisions are made for the health of the land. If they are not, the result could be desertification.

Wild Mustangs—Spotlight on an American Living Legend One type of animal tied closely to rangelands is the wild mustang of the western United States. Although wild horses became extinct in North America 8,000 years ago, horses were reintroduced back in the days of Columbus and Cortez, Italian and Spanish explorers who brought them to North America. Horses quickly became an integral part of the American West. They were used to pull wagons, help build the railroads, carry mail along the Pony Express trail, and plow fields. Many descendants of these domesticated horses escaped and lived life free. Even more were abandoned by settlers, ranchers, mining prospectors, Native American tribes, and the U.S. Cavalry between the late 1800s and 1930s, forming the first wild horse herds. Wild horses are a true living legend of the American West. They are naturally athletic and extremely intelligent. Of no particular breed, their colors are as diverse as their attitudes and abilities. Some say wild horses are born in the colors of the western mountains and snowcapped peaks. As a result of harsh environmental demands and adaptive growth, wild horses possess stronger legs, higher bone density, and harder hooves than domestic horses. The fitness these horses require for survival in the wild is comparable to the level of fitness an Olympic athletic needs in grueling cross-country events. Beginning in the 1920s and continuing through the 1950s, some people saw the wild horse herds as a means to make a quick dollar. “Mustangers,” as they became called, captured then and sold them for pet food. This activity enraged those who considered these majestic


This photo illustrates a roundup of wild mustangs. The Bureau of Land Management uses one of their horses to lead the herd into temporary corrals. The horses are then taken to a medical facility to be examined before they are adopted out to loving homes. (Courtesy of the Bureau of Land Management)

animals to represent the spirit of the West, and led to a public outcry in the late 1960s. The efforts of Nevada’s Velma Johnston (also called “Wild Horse Annie”) and thousands of school children were instrumental in the passing of laws protecting wild horses. The Wild Free-Roaming Horse and Burro Act of 1971 provided for the protection of wild horses on public lands. In 1973, the Bureau of Land Management (BLM), an agency of the U.S. Department of the Interior that is entrusted with managing 264 million acres of public lands (located mainly in the western states), was given the responsibility to manage and preserve the wild horse and

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burro as “living symbols” of the Old West. In 1976, the Adopt-A-Horse program—the BLM’s most popular program to date—was born. This program was designed to remove excess wild horses from the range in order to protect and maintain healthy herds of wild horses and their habitat for future generations to enjoy. The BLM rounds the mustangs up by using a lead horse—called a Judas horse—to lead a herd into a temporary corral. A helicopter flies behind to herd them in the right direction. By taking the weaker horses off the range and placing them in loving homes, it allows the strongest to live on the natural landscape with plenty of food to eat so that the herd will be able to survive and prosper. Since the first horse was offered for adoption in Montana in 1973, BLM has placed more than 185,000 wild horses into private care. The wild horse program is an example of how—with proper land management and care of the environment—the health and welfare of wildlife is maintained, protected, and preserved.

Wildlife Resources Wildlife is a significant part of most landscapes. Each biome supports specific species of wildlife; the wildlife found in deserts is different than that found in the rain forests, which is also different from that found in polar, mountain, or coastal ecosystems. Wildlife cannot exist without its habitat. If the natural habitat changes, it will impact the well-being of the wildlife it supports. Habitat change can be brought about by both natural influences or humancaused influences. A natural influence may be climate change. For example, if a species of wildlife has adapted to survive in a humid climate and the climate changes to a more arid environment, the animal must adapt as well. If it cannot, it will either relocate or die off. This is one explanation that paleontologists have given to explain the extinction of the dinosaurs—the land became too dry to support the animal populations living on them. Human impacts are even more significant. Today, many animals face extinction. They become threatened if they lose their natural


abitat through rain forests being cut down, swamps being drained, h and grasslands being converted into cities. Almost every activity that humans participate in on the landscape has an impact on wildlife. This is one reason why land managers for the National Park Service, U.S. Forest Service, and the BLM teach the “Leave No Trace” concept when people visit natural landscapes—a topic that is covered in more depth in Chapter 8, which deals with conservation methods.

Wetlands Resources Wetlands is the collective term for marshes, swamps, bogs, and similar areas. Wetlands are found in flat, vegetated areas; in depressions on the landscape; and between water and dry land along the edges of streams, rivers, lakes, and coastlines. Wetlands have some of the richest biodiversity on Earth. They are found all over the world from the tropical regions to the polar areas. One of the most important functions of wetlands is their ability to hold large amounts of water—similar to a sponge. By doing this, wetlands help keep river levels normal, and they filter and purify the surface water. Wetlands absorb water during storms and any other time that water levels are high. Conversely, when water levels are low, wetlands slowly release water back into the environment. They act as a reservoir by regulating the availability and effect of water flow. In the past, wetlands were considered wastelands because people could not build homes or other buildings on them. During the early settlements, people drained many swamps in order to build railroads and roads or to develop farmland, thereby destroying the natural wetland environment. As conservation practices have become more widely accepted, and people have learned more about their natural environment, the true value of wetland resources has begun to be recognized. Wetlands have the ability to help control flooding. Because they act like giant, shallow bowls, water collects in them and slows down as it spreads out, making flood management much easier. They then slowly release floodwaters back into streams, lakes, and groundwater, making

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flooding impacts less damaging. One acre of wetlands can store more than 360,000 gallons (1,362,748 liters) of water if flooded to a depth of one foot (0.3 m). This helps reduce property damage and loss of life in the United States when winter snow melts and becomes spring runoff. In the 1600s, more than 220 million acres of wetlands existed in the conterminous United States (excluding Hawaii and Alaska). Unfortunately, since then, great losses have occurred, with many of the original wetlands drained and converted to farmland. Today, less than half of the nation’s original wetlands remain. Wetlands also provide critical services to wildlife. They function as migratory rest stops for thousands of birds each year on their way to their summer or winter homes. Wetlands provide a wealth of energyrich resources to migratory birds. They also provide homes for young organisms that need the protection of the grasses, more shallow water, and a sufficient food supply to grow into adults. Wetlands also protect coastal areas by absorbing pollutants and excess nutrient compounds that would otherwise drain directly into the ocean, upsetting the chemical balance of the marine environment.

Energy Resources/Mineral Resources Energy and mineral resources are some of the most important resources for humans with regard to changing and improving the quality of life. Forms of energy resources that come from the Earth include fossil fuels (coal, oil, and gas), hydroelectric power, wind energy, wave energy, and geothermal energy. Some of these resources are renewable and some are considered nonrenewable. Renewable energy is energy that can be regenerated, such as hydroelectric energy—energy generated from falling water (in dams). Organic matter that comprises plants is a form of renewable energy called biomass. Biomass can be used to produce electricity, transportation fuels, or chemicals. This is called biomass energy. Wood is another renewable resource because more trees can be grown to make more wood (as long as the sustainable yield is not exceeded with the trees or the soil). Renewable energy resources also include geothermal


energy—a form of energy that is generated from beneath the surface of the Earth—and wave energy, which is energy generated from the motion and power of the ocean’s waves. Nonrenewable resources that people use, which cannot be replaced, are the fossil fuels—the energy resources that are generated from oil, gas, and coal. The uranium that is used in nuclear power plants is also a nonrenewable resource. Coal provides the energy needed to generate more than half of the United States’ electricity. Oil is the source of gasoline used to power cars, trucks, and boats, as well as being a source of compounds that go into making plastics, synthetic materials, and even medicines. Natural gas is used to heat many homes. Energy resources are extremely valuable. Humans use all these energy sources to generate the electricity needed for homes, businesses, schools, churches, stores, and factories. Electricity enables people to have computers, lights, refrigeration, washing machines, stereos, air conditioners, curling irons, blow driers, alarm clocks, fax machines, as well as many other things that they depend on each day. The development of energy resources also provides jobs for many people and contributes to the nation’s economic health. Removing coal, oil, and natural gas from the Earth, however, can impact the environment. Therefore, scientists need to study ways to minimize the negative effects of developing and using energy resources. Energy produced from hydrogen, for example, would have no adverse effects in terms of contributing to pollution and the greenhouse effect, because its primary waste is water. For this reason, scientists are currently trying to develop cars that will run on hydrogen in the future. Mineral resources are also extremely valuable. Many minerals are mined from the Earth. Minerals are an important part of human’s lives every day; for example, in the use of metal ores to make cars, build buildings, and construct bridges and in the use of semiprecious minerals to make jewelry. Minerals and products from minerals are used in many manufacturing and industrial processes for commodities that have given Americans the lifestyle they enjoy today.

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These minerals are considered nonrenewable because they cannot be replenished within one generation of a human lifetime. For this reason, it is extremely important to wisely manage these resources so that they will continue to benefit people’s lives in the future.

Grassland Resources Grasslands are among the most biologically productive of all natural communities on Earth. They are very fertile because they have the ability to retain nutrients, support a vast population of biological resources, and provide habitat for many different types of plant and animal life. Grasses have also contributed the genetic material for the major human food staples (crops)—rice, wheat, corn, and other grains. In fact, worldwide production of these grain crops exceeds all other food crops combined, making grasslands one of the Earth’s most critical natural resources. Grasslands also contribute immense value to watersheds and provide forage and habitat for large numbers of domestic and wild animals. The Earth offers many important natural resources. Because everything is ultimately connected in a system, how well resources are managed will determine their use and value for future generations.

CHAPTER

4

The Development of Land Resources

T

his chapter will explore the development of the land’s resources. It examines the development of land and the concept of multiple use; the various biogeochemical cycles that shape and sustain the land; the land’s role in the food chains critical to supporting healthy life; and natural hazards that interfere with development of the land.

The Development of Land and the Concept of Multiple Uses Land is developed for many purposes—a concept called multiple use. What the land can be used for is determined by the characteristics of the land and the natural resources available. For example, in order for the land to be able to support wildlife such as bears, elk, and moose, there must be forested areas for their habitat and an availability of the food they need to eat. If habitat or food supply is removed, the land will no longer support the wildlife that live there, and the animals will 73

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either have to relocate to an area that does have the necessary resources or die out. Similarly, when cities began to be built, because water is an essential resource, the initial significant settlements were built along viable (useable) waterways—such as the early civilizations that began along the Nile River. A source of water and a source of nutrient-rich land in which to farm were two of the major reasons cities originally grew where they did. Because land is such a critical resource and can be potentially used for different purposes, land managers must manage land with several applications in mind—a concept called multiple use management. Multiple use management is a balancing act, because some uses may impact other uses to the point the land is no longer suitable for multiple use. The largest conflict of land use is between urbanization and wildlife habitat, which involves their competition for use of the land. This competition for land use happened with the exploration, expansion, and settlement of the American West. An abundance of wildlife can survive where there is a large amount of wild undeveloped places and intact wildlife habitat. Before rapid exploration and settlement began in the western United States, huge herds of buffaloes—also called bison—roamed the open ranges in numbers ranging in the millions. When people began moving into the area and converting wideopen cores of buffalo habitat to urban use by building houses and roads, it began to affect the natural habitat for the wildlife. Settlers also began hunting and killing the buffaloes, eliminating large herds of these animals. They were hunted so extensively that today there are very few buffaloes left. The same types of human impact are still happening today as more land is developed for human use. Wildlife needs large core areas of natural habitat in order to survive and flourish. Some of these core areas of habitat are currently protected by the U.S. government, which has set aside areas as national parks and wilderness. Conservation biologists have proved time and again that protecting these large areas

The Development of land resources

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Human encroachment on the land can cause conflicts with wildlife habitat. (a) Near Jordanelle Reservoir in Utah, heavy equipment is removing natural vegetation from the hills in order to build homes. This area is the natural habitat of deer, elk, and moose. (b) This resort near Park City, Utah, has destroyed wildlife habitat in order to create ski runs, erect ski lifts, and build a lodge at the base of the resort. (Photos by Nature’s Images)

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of wild habitat—or cores—is essential to the long-term health of wildlife populations. A major problem with developing urban areas within principal wildlife areas is that animals’ habitats become fragmented—instead of having a large natural area to live in, it is broken into smaller separated segments, causing isolated “islands” of habitat. This resulting fragmentation of habitat through the development of areas by roads, houses, and other activities will eventually encourage extinction of the species. One multiple-use solution to this conflict is to develop wildlife migration corridors. As the surface of the land is altered for human use, impacts to wildlife are inevitable. When ranchers maintain herds of cattle on rangeland, they fence in their properties to keep the livestock contained. This, however, keeps wildlife out of the area, and they no longer have access to food sources they once relied on. Recreation is another use of the land that can have a detrimental effect on wildlife. Ski resorts can disturb wildlife migration and feeding habits by eliminating a possible food source as well as introducing noise and activity into the previously peaceful area. Urbanization is one of the most detrimental impacts of all. As towns and cities spread outward, the native wildlife habitat is impacted. When homes and roads are built, the natural vegetation is often clearcut (removed) from the area. This eliminates food sources for wildlife. The presence of roads also presents a major problem, because animals get hit and killed by cars while crossing the highways, often while they are searching for water. Once housing replaces natural habitat and the native plant species are removed, other nonnative plant species (plants that do not naturally grow there) are introduced. These are called invasive species. Invasive species can then compete with the existing native vegetation. Because invasive species have not been there long enough to have natural enemies, they can often grow out of control and spread. Not only can these species be destructive to the native vegetation, but they can also harm animals if they are poisonous or the animals simply do


not find them palatable (edible). In this way, they have removed a food source, which then threatens the health and future of the habitat. With so much demand placed on the land for both human and wildlife needs, it is critical that resources and the lands that contain them be managed effectively so that habitats do not become diminished or changed adversely. There are many possible uses of the land, and many of them overlap. For example, some areas may be suitable for wildlife habitat; recreational activities such as camping, backpacking, and hiking; mining commodities, such as gold, silver, limestone, copper, and many other elements; and the logging (cutting down of trees) to use in the timber industry for construction and firewood. Urbanization, as mentioned, is a significant use of the land. Accompanying this is the construction of hundreds of miles of roads. Railways can be constructed, as well as power lines and pipelines for electricity, gas, and water. These areas are usually surrounded by buffers called rights-of-way. Agricultural development is another major multiple use impact. Although necessary for human survival, growing crops has its impacts. Not only does it replace the native vegetation, but monocultures— growing only one crop on a piece of land—lowers biodiversity, nutrients to the soil, and can cause erosion. It also increases the risk of disease affecting large areas. If one plant in a crop is killed by a disease, it can destroy the entire crop. In areas with a mixture of different plants, the rate of survival is naturally higher because not all types of plants may be harmed by a particular disease. Hunting is another use of the land introduced by humans. Without effective limits and restrictions from proper management, species could be hunted to extinction. In areas where water is a resource, such as streams, rivers, reservoirs, wetlands, lakes, and oceans, there can be conflict between the aquatic wildlife and recreation. Activities that compete with wildlife include river rafting, fishing, boating, waterskiing, and scuba diving. If humans are not mindful of the wildlife they are sharing the land with, there can be substantial impacts. For example, polluting water

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bodies can destroy the habitats of fish and other aquatic animals. Polluting the water can involve chemicals, garbage, or even dumping too much sediment into waterways from construction and erosion. It is not only dangerous to the wildlife, but also impacts the food supply for people, as well. Wetland areas are used by many birds as nesting areas. Polluting or destroying wetlands takes away a crucial area needed by many birds for survival. Another threat to wildlife concerns introduced animal species. When humans move into an area and bring other animals with them, it can have a long-lasting effect on the native species. For example, introducing dogs into a woodland area threatens smaller animals such as rabbits, mice, squirrels, and chipmunks, because they can be hunted and eaten by the dogs. In some island areas, new animals have been introduced. Because islands are relatively isolated places, their endemic species have adapted to their habitats. When a competitive animal is introduced, the endemic species can directly die off from being hunted or from having to compete with the new animal for food and starving off. Introduced species can also introduce new diseases that the native species have never been exposed to. Because the native species have no natural defenses against new diseases, they can be vulnerable and die. All these issues have to be considered by scientists and land managers, and plans need to be put in place to help all forms of life.

Biogeochemical Cycles—Maintaining a Balance There are several natural cycles in nature that support and determine the use of the land. Four critical cycles pertaining to land resources are the rock cycle, the hydrologic (water) cycle, the carbon cycle, and the nitrogen cycle. The inorganic nutrients in an ecosystem cycle through more than just the organisms. They also enter into the atmosphere, the oceans, ground, and rocks. Because chemicals cycle through the biological world (living things) and the geological, or physical, world (the oceans,


land, and atmosphere), the cycles that affect ecosystems are often referred to as biogeochemical cycles. Each chemical is unique and has its own properties, but all of these cycles share things in common. When chemicals are held in storage for long periods of time, they are contained in reservoirs. When a chemical is not held in a particular place for a long time—but moves from place to place over a shorter period of time—the chemical is in an exchange pool. The amount of time a chemical is held in an exchange pool or a reservoir is called its residence time. In the case of water, when water is stored in groundwater or the oceans, it is a reservoir because it stays there for a long time. When water is in the form of rain, snow, or a cloud, it is in an exchange pool because it remains in that part of its cycle for a relatively short time. The biotic community in an ecosystem includes all the living organisms, large and small. The biotic system serves to move chemicals from one stage to another. For example, the water that trees take from the ground is then evaporated into the atmosphere. The sun and the heat from the mantle and core of the Earth are what provide most of the energy to transport the chemicals.

The Rock Cycle The Earth is very active. Every day, volcanoes can be erupting, while earthquakes are shaking. Mountains are being pushed up and worn down, rivers carry sand and mud into the sea, and tectonic plates move. Rocks do not remain the same over time, either. Rocks take different forms at different times. In the geologic past, the Earth was very volcanic. As the volcanoes cooled and vast oceans developed over the Earth, the cooled lava was broken or crushed into small pieces during the continual process of erosion. These small pieces were then cemented together over time to become sedimentary rocks. These rocks were then buried, and the Earth’s heat and pressure changed them into metamorphic rocks. The crystalline structure of the rock changes during the

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This diagram illustrates the continuous cycle rocks go through as they change from igneous to sedimentary to metamorphic rocks.

metamorphic process. If the rock has crystals already, it forms larger crystals. Over time, metamorphic rocks can be melted inside the Earth and become igneous rocks once again. A rock may make this transformation many times. This process is called the rock cycle. Scientists believe that rocks at the edges of crustal (tectonic) plates are being recycled relatively quickly. Magma comes to the surface along the mid-ocean ridges and near the trenches. Where the plates collide or move past each other, heat and pressure change these rocks as well. In trenches, old rocks are constantly being forced down into the mantle. There they are melted and mixed with other rock material, which then makes its way back to the surface as lava or magma. This recycling has been going on since the Earth was formed and will continue as long as the Earth exists, molding and remolding the face of the planet.


Rocks of every type are worn away over time. Weathering is the process that breaks rocks into smaller bits. There are three main types of weathering processes: • Physical weathering—where a physical action (such as freezing and thawing) breaks up the rock. • Chemical weathering—when a rock is chemically attacked, such as limestone being eroded by acid rain. • Biological weathering—when rocks are weakened and broken down by animals and plants, such as a root system that splits rocks. Different types of rocks are weathered at different rates. The rock cycle takes hundreds of millions of years. Once a rock has been broken down into smaller pieces, it is transported by wind or water and deposited in other locations, which can eventually become sedimentary rocks that are formed layer by layer. Sedimentary rocks are formed in three steps: (1) layers of sediment are deposited at the bottom of seas and lakes; (2) over millions of years, the sediment layers get buried by additional layers; and (3) the salts that are present in the layers of sediment begin to crystallize as the water is squeezed out. The salts serve to cement the particles together. Sedimentary rocks have a horizontal banded appearance of layer upon layer. Only sedimentary rocks contain fossils, making these rocks helpful to scientists when they try to reconstruct an area’s geologic and biologic history, because each layer serves as a record of past events. Scientists are able to portray the land’s past because these layers serve as a special history record set in stone. Examples of sedimentary rock include sandstone and limestone. Metamorphic rocks are subjected to enormous amounts of heat and pressure, which causes the crystalline structure and texture to change. Metamorphic rocks include slate and marble, both of which are resources used today in construction.

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Igneous rocks are made from molten rock. They contain crystals—the size depends on how they were cooled. Above ground, they are called extrusive igneous rocks and have small crystals because they cooled rapidly. Large crystals form if the rock cooled slowly underground; these are called intrusive igneous rocks. The type of rock formation often determines what can be built upon it. These types of formations can also be indicators of the land’s condition and stability. When certain features are present, such as geologic faults, large areas of limestone, or high concentrations of clay in soils, this can be an indicator that construction of homes, highways, and other features may not be wise. These are areas that could have earthquakes, sinkholes, or landslides, which will be discussed later in this chapter.

The Hydrologic (Water) Cycle Water is necessary for animal survival, plant growth, for dissolving and transporting plant nutrients, and for the survival of soil organisms. The water cycle is fundamental to all living things on Earth. Water is always in motion, whether it is in the form of rainfall, rolling ocean waves, a swift-flowing river, or water moving slowly underground. The endless movement and recycling of water between the atmosphere, the land’s surface, and underground is called the hydrologic cycle, or water cycle. Two separate forces make the water cycle work: the energy of the sun and the force of the Earth’s gravity. Water vapor is carried through the atmosphere by air currents. When the air cools, it condenses, forming clouds. Some of the moisture falls back to Earth as rain, snow, hail, or sleet. Once the water reaches the ground, it can go in several directions before it returns again to the atmosphere. The water can be used by animals and plants, it can be stored in lakes, or it can seep into the soil. The sun’s energy can then make the water evaporate back into the atmosphere, or the Earth’s gravity can pull the water that has entered the ground down through the soil to be stored for years as slowly moving groundwater.


Water is constantly changing states from vapor to liquid to ice. Water can be stored in oceans, lakes, rivers, as snow on mountains, and in huge reservoirs underground.

Groundwater can be stored in aquifers (natural underground reservoirs), or it can eventually seep into springs and resurface. Water on the surface is returned to the atmosphere through the process of evaporation. Water that has been used by plants is returned to the atmosphere as vapor through transpiration, which happens when water passes through the leaves of plants. These two concepts together are called evapotranspiration. Evapotranspiration is greatest in areas that are hot, dry, sunny, or windy. Although water is critical for animal survival, plant growth, and transporting nutrients, it can also be a destructive force if not managed

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properly. It can cause soil compaction, which clumps the particles of soil close together and removes the important air space needed for nutrients to move through the soil; it can leach (remove) nutrients from the soil; and too much water can cause excess runoff and erosion.

The Carbon Cycle The carbon cycle is important because carbon is the basic structural material for all cell life. Carbon makes the soil productive and plants healthy. The carbon cycle is the movement of carbon between the atmosphere, the oceans, the land, and living organisms.

Carbon, essential to many processes on the Earth, can be stored in the atmosphere, oceans, land, and trees.


The atmosphere and plants exchange carbon. Plants absorb carbon dioxide from the atmosphere during photosynthesis and then release carbon dioxide back into the atmosphere during respiration. Another major exchange of carbon dioxide happens between the ocean and the atmosphere. The dissolved carbon dioxide in the oceans is used by ocean plants in photosynthesis. Carbon is also exchanged through the soil. Crop and animal residues decompose and form organic matter, which contains carbon. For plants to be able to use these nutrients, soil organisms break them down in a process called mineralization. Animals also give off carbon dioxide when they breathe. Some plants are eaten by grazing animals, which then return organic carbon to the soil as manure. Easily broken-down forms of carbon in manure and plant cells are released as carbon dioxide. Forms of carbon that are difficult to break down become stabilized in the soil as humus.

The Nitrogen Cycle The nitrogen cycle is the process by which nitrogen in the atmosphere enters the soil and becomes part of living organisms before returning to the atmosphere. Nitrogen makes up 78% of the Earth’s atmosphere— but this nitrogen must be converted from a gas into a chemically usable form before living organisms can use it. This transformation takes place through the nitrogen cycle and transforms the nitrogen gas into ammonia or nitrates. Most of the nitrogen conversion process is done biologically. This is done by free-living, nitrogen-fixing bacteria; bacteria living on the roots of plants; and through certain algae and lichens. Nitrogen that has been converted to ammonia and nitrates is used directly by plants and is absorbed in their tissues as plant proteins. The nitrogen then passes from the plants to herbivores and then to carnivores, both of whom eat the plants. When plants and animals die, the nitrogen compounds are broken down by decomposing into ammonia. Some of this ammonia is then used by plants, and the rest is either dissolved or held in the soil. If the

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The nitrogen cycle is the process by which nitrogen in the atmosphere enters the soil and becomes part of living organisms before returning to the atmosphere.

ammonia is dissolved or held in the soil, microorganisms then go to work on it in a process called nitrification. Nitrates can be stored in humus or washed from the soil and carried away to streams and lakes. Nitrates may also be converted and returned to the atmosphere by a process called denitrification. The nitrogen cycle is important because plants need nitrogen to grow, develop, and produce seeds. The main source of nitrogen in soils is from organic matter (humus). Bacteria that live in the soil convert organic forms of nitrogen to inorganic forms that plants can use.


Nitrogen is then taken up by plant roots. When plants die, they decay and become part of the organic matter in the soil. The land must be well managed, or nitrogen can be washed out of the soil.

Food Webs Food webs represent a complex network between living organisms (plants and animals) and the vast resources of the land. For instance, the land must grow the plant that is at the bottom of the food web and the land must also provide adequate habitat for the other members of the local food web to survive. Energy flows through an ecosystem just as water, carbon, and nitrogen do. Energy is transferred through a community as organisms produce and consume food. Energy flows from producers to consumers as each population eats and is eaten. A food chain is a series of organisms that feed on other organisms. For example, if grass is at the beginning of the chain, it may then be eaten by a grasshopper. The chain continues as a mouse eats the grasshopper, a snake eats the mouse, and finally, an eagle eats the snake. In this example, grass is at the bottom of the food chain, and the eagle is at the top. Green plants are the primary producers, because they trap the energy from the sun and use it to produce starch. Energy passes from the plants to all other life. Plants (producers) are eaten by herbivores (vegetable-eating animals such as caterpillars and cattle). These are the primary consumers. The animals that eat the herbivores are called secondary consumers and are meat eaters, or carnivores. Higher consumers, in turn, may eat these secondary consumers. When plants and animals die, the energy that remains is used by scavengers, like vultures, and smaller creatures, like worms. The large remains are broken down into smaller pieces that bacteria and fungi— the decayers—can use as an energy source. The results of the decayers’ activities are the nutrients, which can be absorbed by plants, and waste energy, which is lost as heat. In this way, the energy from the sun is never destroyed as it passes down the food chain. It is just changed into different forms.

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A typical North American food web.

The real world is much more complicated than a simple food chain, however. A food web is a series of interlinking food chains, and is much more complex than a singular food chain. In a food web, members can be part of more than one food chain. Food webs illustrate the interdependence of all biotic factors in an ecosystem on the land.


Maintaining a healthy balance has a direct impact on food chains and food webs. If a toxic substance enters the web at any point, anything else that feeds off on it is at risk for contamination. If key organisms or multiple groups disappear, it can cause severe problems in food chains and food webs. As chains move from soils to plants to animals to humans, it is not hard to see why maintaining a working system is important. If any part of these systems fail, then everything up the food web from that point can be negatively impacted. This relates back to the renewability versus nonrenewability issues of land resources. If a system or multiple systems are completely destroyed, resources can become nonrenewable. The land’s soil resources directly affect the health of food chains. Whatever types of plants the local soil can support will determine which life-forms can inhabit the area. Five factors determine what types of soil form on the land: (1) parent material, (2) organisms, (3) topography, (4) climate, and (5) time. Parent material is the primary material from which the soil is formed. Soil parent material can be bedrock; organic material; deposits from water, wind, glaciers, and volcanoes; or an old soil surface. Bedrock is broken down as weathering processes wear away the mineral particles from rocks. Organisms that live in the soil along with decaying organic matter from leaves and dead plants change the soil’s chemistry. The most fertile soils have healthy amounts of nitrogen (N), phosphorus (P), and potassium (K). In order to grow healthy and strong, plants need these three elements. Topography, or how steep or flat the land is, also affects soil through its reaction to climatic processes. Soils at the bottoms of hills get more water than soils on slopes. Soils on slopes that face the sun are drier than soils on slopes that do not face the sun. Topography also affects mineral accumulations, type of vegetation, plant nutrients, erosion, and location of streams, which in turn affects soil formation. Climate plays an important role. Heating, cooling, wetting, and drying all help break down the parent material that forms the soil.

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Climate also determines how fast this breakdown occurs. Time is a critical factor. The longer the natural soil-forming processes occur, the more soil is developed. Soil protects plant roots from exposure to the sun’s heat. Soil also filters pollution that comes from rain and water runoff from farms. Plants utilize soil to grow and receive support while they grow. Soil is an important natural resource that directly determines the level of biodiversity the area can support.

Natural Hazards on the Landscape Understanding the mechanisms of natural events, such as earthquakes, volcanic eruptions, landslides, and floods, is important for the United States, as well as the rest of the world. According to the U.S. Geological Survey, natural disasters have cost the United States $50 billion in recent years. There are several natural processes of the landscape that can pose problems to human habitation and wildlife habitat in certain areas. For this reason, land-use planners have a critical job. If towns are developed along fault lines and an earthquake hits, it can completely destroy the town, and the loss of human life will be great. Likewise, when communities are built on unstable slopes or close to forested/woodland areas, hazards—like landslides and wildfires—can occur and cause great damage. By better understanding why natural events occur, land managers can plan in ways that will lessen the severity of these hazards. Through scientific research, earth science educational programs, and planning preparedness, not only will the damaging effects of natural hazards be reduced, but scientists will better understand the Earth. In order to accomplish this, land-use planners must work closely with geologists and hydrologists to determine which land areas may be prone to the processes of natural hazards and should therefore be avoided for development. Because the natural processes of the land can be powerful and unpredictable, it is also important for residents


already living in areas that are prone to natural hazards—such as earthquakes, volcanoes, landslides, floods, and wildfires—to be aware of the situation and have an emergency preparedness plan in place in case a disaster occurs.

Earthquake Hazards One of the most destructive phenomena of nature is an earthquake. An earthquake is a sudden movement of the Earth’s crust, caused by the abrupt release of strain that has accumulated over a long time. If an earthquake occurs in a populated area, it may cause many deaths and injuries, along with extensive property damage. The study of earthquakes is relatively new. Until the eighteenth century, few factual descriptions of earthquakes were recorded, and the natural cause of earthquakes was not understood very well. Today, scientists have begun to estimate the locations and likelihood of future earthquakes. Sites of greatest hazard are being identified, and engineers are designing buildings that will withstand the effects of earthquakes. When existing buildings are renovated, many cities’ building codes require building improvements to be made that are designed to make the structure safer in case of an earthquake. Most earthquakes occur at the boundaries where the Earth’s tectonic plates meet. In fact, the locations of earthquakes and the kinds of ruptures they produce help scientists define plate boundaries. There are three types of plate boundaries: spreading zones, transform faults, and subduction zones. Most spreading zones are found in the oceans—for example the Mid-Atlantic Ridge. Spreading zones usually have earthquakes at shallow depths (within 18.6 miles, or 30 km) of the surface. Transform faults occur where plates slide past each other, such as the San Andreas Fault in California. Subduction zones are found where one plate overrides another. Subduction zones are characterized by deep-ocean trenches, shallow-to-deep earthquakes, and mountain ranges containing active volcanoes. These areas exist along the northwest coast of the United States, western Canada, and southern Alaska.

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Earthquake Preparedness The following are things you should know in case of an earthquake: • Only if you live in an old, unreinforced adobe house, should you head for the doorway. In modern homes, doorways are no stronger than any other parts of the house and usually have doors that will swing and can injure you. You are safer practicing the “duck, cover, and hold” under a sturdy piece of furniture. • Make sure each member of your family knows what to do no matter where they are when an earthquake occurs. Set up a meeting place where you can reunite afterward. • Know where your gas, electric, and water main shutoffs are and how to turn them off if there is a leak or electrical short. • Locate your nearest fire and police stations and emergency medical facility. • Emergency supplies to have on hand should include a fire extinguisher, adequate supplies of medications that you or family members are taking, crescent and pipe wrenches to turn off gas and water supplies, first-aid kit, flashlights with extra bulbs and batteries, portable radio with extra batteries, water for each family member for at least three days and water purification tablets, canned and packaged foods, camp stove, and waterproof bags for waste disposal. • If you are indoors—stay there! If you are outside—get in the open away from buildings, power lines, and anything else that might fall on you. • Do not turn on the gas if it has been turned off; do not use matches or lighters; do not use your telephone, except for a medical or fire emergency. Source: U.S. Geological Survey


Volcanic Hazards Volcanoes erupt at the edges of the Earth’s tectonic plates. The Pacific Ring of Fire is the world’s best-known example of volcanic activity triggered by the movement of the Earth’s plates. Some volcanic eruptions are explosive, and others are not. How explosive an eruption is depends on how runny or sticky the magma is. If magma is thin and runny, gases can escape easily from it. When this type of magma erupts, it flows out of the volcano. Lava flows rarely kill people because they move slowly enough for people to generally get out of their way. The volcanoes in Hawaii are an example of a slow-moving flow. Lava flows, however, can cause considerable destruction to buildings in their path. If magma is thick and sticky, gases cannot escape easily. Pressure builds up until the gases escape violently and explode. In this type of eruption, the magma blasts into the air and breaks apart into pieces called tephra. Tephra can range in size from tiny particles of ash to house-size boulders. Explosive volcanic eruptions can be dangerous and deadly. They can blast out clouds of hot tephra from the side or top of a volcano. These fiery clouds race down mountainsides destroying everything in their path. Ash that erupts into the sky falls back to Earth like powdery snow. When hot volcanic materials mix with water from streams or melted snow and ice, mudflows form. Mudflows have buried entire communities located near erupting volcanoes. Over geologic time, many volcanic eruptions have produced mountains, plateaus, and plains, which erosion has molded into beautiful landscapes with fertile soils. Ironically, volcanic soils and the conducive terrain have attracted people over time to build homes on or near volcanoes. As population density increases in regions of active, or potentially active, volcanoes, humans need to be aware of the hazards and not build too close to them. People living in the shadow of volcanoes must live in harmony with them and expect—and plan for—periodic violent unleashings of volcanic energy.

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a

b

c

d

Examples of past natural disasters are shown in this series of photos. (a) An earthquake on March 27, 1964, damaged homes in Anchorage, Alaska. (b) Mount St. Helens erupted on August 7, 1980, in Skamania County, Washington. (c) A 2001 earthquake-induced landslide buried parts of a neighborhood near San Salvador, El Salvador. (d) This house in Laguna Beach, California, was destroyed by a landslide in 2005. (a, b, courtesy U.S. Geological Survey; c, photo by Ed Harp, courtesy U.S. Geological Survey; d, U.S. Geological Survey, photo by Pam Irvine.)


The short-term hazards posed by volcanoes are balanced by benefits of volcanism and related processes over geologic time. Volcanic materials ultimately break down to form some of the most fertile soils on Earth. People use volcanic products as construction materials, as abrasives and cleaning agents, and as raw materials for many chemical and industrial uses. The internal heat associated with some young volcano systems has been harnessed to produce geothermal energy. The challenge to scientists involved with volcano research is to minimize the short-term adverse impacts of eruptions so that society may continue to enjoy the long-term benefits of volcanoes. They must improve the ability to make predictions and provide helpful information so land-use planners can make safe decisions.

Landslide Hazards Landslides are termed the “sleeper” of all geologic hazards. Although triggered by snowmelt, rain, poor excavation, or earthquakes, they sometimes startle the unsuspecting homeowner with the fierceness of their rapid movement or the slow stretching of once-peaceful terrain. According to the U.S. Geological Survey, landslides constitute a major geologic hazard because they are widespread, occurring in all 50 states, and cause $1 billion–$2 billion in damages and more than 25 fatalities on average each year. Landslides pose serious threats to highways and structures that support tourism, timber harvesting, mining, energy production, and general transportation. Landslides commonly occur with other major natural disasters, such as earthquakes, volcanoes, wildfires, and floods. Expansion of urban and recreational development into hillside areas and other land use has increased the likelihood and frequency of landslide disasters. Landslides are common in many places in the United States. For instance, they are common throughout the Appalachian region and New England in the East; the Ohio, Missouri, and Mississippi valleys in the Midwest; and all mountainous areas of the West. Landslides are also common in Alaska and Hawaii.

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Causes of Landslides There are three major causes of landslides: geological, morphological, and human causes. 1. Geological causes: • Weak or sensitive materials • Weathered materials • Sheared, jointed, or fissured materials • Adversely oriented bedding • Contrast in the permeability or stiffness of materials 2. Morphological causes: • Tectonic or volcanic uplift • Glacial rebound • Erosion at the bottom of slopes • Underground erosion • Overloading of deposits on a slope • Vegetation removal (by fire or drought) • Freeze/thaw weathering • Shrink/swell weathering 3. Human causes: • Excavation of a slope • Loading a slope or its crest • Drawdown of reservoirs • Deforestation • Irrigation • Mining • Artificial vibration • Water leakage from utilities Source: U.S. Geological Survey

Major hazards in the eastern United States are from debris flows and from the sliding of soils. Landslides have also caused serious property damage along the shores of the Great Lakes and on the bluffs of major rivers throughout the Midwest. Huge landslides occur


in weathered shale, hydrothermally altered volcanic rocks, and other rocks in mountain ranges of the western states. Debris flows occur wherever rock composition and weathering patterns produce ample loose material on steep slopes; periodic heavy rains or rapid snow melt trigger debris flows in these areas. Loss of vegetation and groundcover that occurs during wildfires further enhances debris-flow susceptibility. Major storms have caused widespread flooding and landslide events along the Pacific coastline of Washington and Oregon. They have also caused thousands of debris flows in California. Rock fall is a serious hazard in many mountainous areas of the United States and a major cause of landslide fatalities. The Landslides Hazards Program, developed by USGS, functions to reduce long-term losses from landslide hazards by improving people’s understanding of the causes of landslides. The program was begun in the mid-1970s by gathering information, conducting research, responding to emergencies and disasters, and producing scientific reports. Several professions—such as geologists, engineers, experts in academia and private practice, planners, and decision-makers—use the data to increase their understanding of these natural hazards to prevent disasters and save lives.

Flood Hazards Floods are the accumulation of too much water flowing into a place at once. They can result from natural forces or may be caused by human activity. Examples of different types of floods are flash floods; regional floods; storm surge floods; dam and/or levee failure floods; and debris, landslide, and mudflow floods. According to data from the U.S. Geological Survey, during the twentieth century, floods were the number-one natural disaster in the United States in terms of lives lost and property damage. They can occur at any time of the year, in any part of the country, and at any time of the day or night. Most lives are lost when people are swept away by flood currents, whereas most property damage results from

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huge amounts of sediment-laden water. Flood currents also possess tremendous destructive power, as lateral forces can demolish buildings and erosion can undermine bridge foundations and footings, leading to the collapse of these structures. There is also a positive side to floods. Overflowing waters can bring sand, silt, and debris onto the flooded banks, which leaves soil fertile with minerals and organic matter that serves as natural fertilizers. Floods have the ability to permanently rearrange the landscape, however. Oftentimes, people build towns or other developments on existing floodplains because their flatness makes them ideal areas to build on; but because these areas are already susceptible to flooding, construction in these areas poses a risk.

Wildfire Hazards Wildland fire is a serious and growing hazard over much of the United States, posing a great threat to life and property, particularly when it moves from forest or rangeland into developed areas. Wildland fire, however, is also a natural process, and its suppression is now recognized to have created a larger fire hazard, as live and dead vegetation accumulate in areas where fire has been excluded. This was a hard lesson learned during the Yellowstone Fires of 1988, of which more than 793,000 acres (36% of the park) were affected by fire. According to the National Park Service, about 300 large mammals (mainly elk) were killed in this fire. It cost more than $120 million to fight it; and more than 25,000 people participated in the firefighting effort—the largest in U.S. history. Scientists have also determined that the absence of fire has altered or disrupted the cycle of natural plant succession and wildlife habitat in many areas. For these reasons, government land management agencies—such as the BLM and USFS—use methods such as prescribed burning to reintroduce fire into natural ecosystems. Problems arise when people build too close to natural forested areas. In many areas of the country, homes are not only built up to the edges of the thick forests, they are built within the heavy forest stands as well.


Many wildland fires—particularly in the western United States—are caused by natural lightning strikes. When this happens near populated areas, there is a great risk that homes will be destroyed by wildfires. Each year in the United States, populated areas must be evacuated. One of the most difficult aspects for firefighters is that the direction in which the fire moves can suddenly change with the variable wind directions. This unpredictability increases the danger of living too close to wooded areas. Sometimes residents don’t get much advanced notice when it is necessary to evacuate. One way that people can help firefighters when they live in these areas is by keeping shrubs and trees thinned out within their yards and in the areas surrounding their homes.

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5

Multiple Uses of the Land

T

his chapter will explore the multitude of uses that occur on the land today and the subsequent results of those uses. It discusses the critical role that public domain lands play in the United States, the importance of mapping and interpreting the landscape, methods by which land resources become polluted, and various human impacts on the environment.

The Importance of Public Lands Public lands are those lands that are administered by the federal government. Different federal land management agencies manage different lands—such as the Bureau of Land Management (BLM), the U.S. Forest Service (USFS), and the National Park Service (NPS). (The total area of the United States is 2.3 billion acres.) The first public domain was created in 1781 when New York agreed to surrender to the federal government its claim to unsettled territory that extended westward to the Mississippi River. Other colonies followed New York’s example, and 100

Multiple Uses of the land

Oil and gas exploration is one of the many uses of public lands. (Courtesy of the Bureau of Land Management)

by 1802, all of the land west of the colonies between the Appalachian Mountains and the Mississippi River belonged to the federal government. As explorers opened up the West, public domain lands rapidly expanded, and the federal government acquired more than 1.8 billion acres of public domain lands. The nation’s expanding population and mobile society created a demand for a variety of public land uses. Changes in public attitudes and a concern for environmental values and open space began to compete with the need for development and increased production. Congress, recognizing the value of the public domain lands, enacted the Federal Land Policy and Management Act of 1976 (FLPMA). This Act gave the Bureau of Land Management the responsibility to manage the land for multiple uses and to protect the long-term health of the land.

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Today, the BLM takes care of about 262 million surface acres of public land (about one-eighth of the total land of the United States) and approximately 700 million acres of federal subsurface mineral land. The BLM is responsible for managing these lands and their natural resources so that they are utilized in a manner that will best meet the present and future needs of the nation. Maintaining these lands in the right ways is important, because healthy and productive lands and waters support the lives of the natural ecological communities, provide healthy open space with recreational opportunities, help wildlife habitat, provide clean water and air, make energy and minerals available, and provide healthy rangeland for livestock. In order to make these things happen, the BLM depends on the knowledge of many different scientists and management specialists, such as hydrologists, soil scientists, range scientists, recreation planners, wildlife biologists, ecologists, geographers, land-use planners, geologists, mining engineers, archaeologists, paleontologists, foresters, geographic information system specialists, and others trained in specialized, professional fields of natural science. The concept of multiple use is designed to benefit all of the American public, not just a select few. Because of this, there are many different activities that occur on the land at the same time. The BLM leases some of its lands to companies and individuals for mineral exploration and development. This includes mining for commodities such as oil, gas, gold, silver and other metals, oil shale, coal, tar sands, and geothermal energy. Other lands are utilized by BLM’s outdoor recreation program for their scenic and recreational values. BLM manages many different types of ecological environments across the United States (including Alaska). Some of the diverse landscapes include the tundra in Alaska, the deserts of the Southwest, the old-growth forests in the Northwest, and the plateaus and plains of the Rocky Mountain states. Many of these pristine and scenic areas have been designated by Congress or the President of the United States to be national


a

b

(a) Care must be taken when riding vehicles off roads and on hiking trails. (b) All-terrain vehicle use can disrupt wildlife and cause erosion, making it difficult for the land to recover. (Photos by Nature’s Images)

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onuments and wilderness areas—a special status that protects these m lands to ensure they remain pristine. BLM provides many recreational opportunities. Visitors’ freedom to participate in unstructured recreational activities is promoted as long as they accept the responsibility to use public lands wisely and to respect other public land users. Because of this, BLM developed the “Tread Lightly!” and “Leave No Trace!” programs, which are discussed in more detail in Chapter 8 on conservation. The public lands represent some of the United States’ last, great open spaces. They contain exceptional geologic formations; comparatively undisturbed native plant and animal communities; wilderness areas and wild and scenic rivers; and many paleontological, archaeological, and historical sites. All of these natural resources represent a significant part of our nation’s natural and cultural heritage. Because of this, Congress has passed a number of laws concerning the management

Laws to Protect Resources Year passed

Law

Resource protected

1906

Antiquities Act

Paleontology, archaeology

1964

Wilderness Act

Wild lands

1966

National Historic Preservation Act

Cultural

1968

Wild and Scenic Rivers Act

Waterways

1979

Archaeological Resources Protections Act

Archaeology

1990

Native American Graves Protection and Repatriation Act

Cultural, archaeology

Source: Bureau of Land Management


and use of these heritage resources, such as those listed in the table on page 105. One of the serious issues that BLM faces in maintaining the health of public lands (especially in the western United States) is the threat of invasive plants and weeds. Native plants (plants that naturally occur on the landscape) have evolved over millions of years to fill unique ecological niches. Invasive weeds are nonnative (did not originate in the area they are growing in) and ecologically damaging plants. Invasive weeds are plants that developed in other places. When growing in their original regions, they are not considered invasive weeds that harm the environment because they developed within the local ecosystem, which has adapted in order to properly manage them. They are naturally controlled by competition with other plants and by insects, diseases, and other predators. When their population increases in the areas they originated in, insects and other predators keep their numbers under control. The term weed is used to describe any plant that is unwanted and grows or spreads aggressively. An invasive plant is a plant that is growing where it should not be. A pineapple in a pumpkin patch would be an example of an invasive plant because it does not belong there, just as an orchid would be an invasive plant in a strawberry patch. Some invasive plants become a problem because they grow aggressively and crowd out native plants. One of the greatest obstacles scientists and land managers face today in promoting ecosystem health is the rapid expansion of invasive plants. Some invasive plants and noxious weeds can produce significant changes to vegetation, composition, structure, and ecosystem function. These invasive weeds destroy farmland and wildlife habitat and can reduce plant diversity by making it so that other types of plants cannot survive there. Weeds know no boundaries. They are invading public, government-managed land; farms; forests; parks; and private lands. Millions of acres of once healthy, productive rangelands, forested lands, and riparian (river) areas have been overrun by noxious or invasive weeds.

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Invasive weeds can disrupt healthy ecosystems by out-competing the natural vegetation. In the photograph above, thistle, a type of invasive weed, has begun to crowd out other native plants. If these invasive weeds are not removed, there will be a new, larger crop each year. (Photo by Nature’s Images)

Weeds can dominate and cause permanent damage to natural plant communities. Scientists and land managers realize the seriousness of this problem and understand that if weeds are not controlled, they will hurt the health of the land. This problem is especially pronounced in the western regions of the United States. Because so much ranching and grazing of livestock occurs on either private ranches or public lands in the West, weeds pose an increased threat to the health of the land. If weeds are allowed to take over an area and compete with the native plants for soil nutrients and space, the native plants will die. Because livestock graze the native plants and depend on these for their food supply, weeds need to be controlled.


The problem of weeds applies to farming. If weeds invade the fertile land and compete with the crops for nutrients in the soil and growing space, they will keep farms from being as productive. Weeds can spread in many ways: by human activity, birds, animals, wind, and water. Early European settlers in North America unwittingly brought a lot of weed seeds with them. The seeds could have been hidden in the hay they brought over for their animals, in the dirt they used as ballast for their ships, in the fleece and hair of livestock, in their clothes and bedding, or accidentally mixed in with part of the seeds that they brought over to plant as crops. Some human activities, such as clearing the land to build on or to farm, created open places for weeds to grow. Settlers also purposely brought plants from their countries of origin to reseed areas in their new land, make dye for clothing, or use as ornamental plants (as decorations). Some of these introduced plants may have become weeds. When weeds are introduced to a new environment, they may not have any natural enemies to keep them under control. Because of that, insects, plants, or other predators do not destroy them. Without any natural enemies, some of these plants become invasive and lower the diversity and quantity of native plants. Weeds are spreading rapidly in the United States. According to the Bureau of Land Management, in the western United States, weeds are spreading roughly 4,000 acres (more than 6 square miles, or 15.5 square kilometers) each day on public lands. They are also spreading on private lands, including agricultural farming areas. Although some weeds have beautiful flowers, they can cause serious ecological damage. Weeds take over important habitat areas for wildlife, destroying shelter and nutrients and reducing the number and type of native plants that can grow in the area. When weeds do not hold or protect the soil the way native plants do, erosion increases, causing sediments to build up in streams. This in turn can hurt fish populations and water quality.

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Some weeds, called noxious weeds, are a health hazard for humans and animals because they are poisonous. For example, leafy spurge can cause blindness, skin irritation, and blisters. Hemlock is poisonous and can cause death. Other weeds are hallucinogenic and can cause death, and many cause allergic reactions in people. Weeds also pose a problem in controlling wildfires. Generally, they are less resistant to wildfire than native plants. Weeds also reduce the value of the land. They have a huge impact on ranching and agricultural activities because they can reduce the production of crops. Weeds are a problem all across the country, and controlling them can be very difficult. Once farmers, ranchers, and others realize that there is a weed infestation, it usually has become big enough so that it is hard and expensive to eradicate. Biological control (using organisms such as introduced insects or diseases to reduce populations) is effective in slowing the spread of weeds, but it usually cannot get rid of all the weeds. Farmers and ranchers can pull the weeds by hand or use machines to dig them up, but this is usually only done with small infestations. When farmers pull weeds, they must be careful that they do not accidentally spread any new seeds. Herbicides are also good for controlling weeds and stopping their spread when they are found early. Most land managers use an integrated approach, using a combination of these methods. It is important in agriculture, ranching, and other activities to learn about weeds and get rid of them. A naturally functioning ecosystem can easily be thrown out of balance by an invading species. Controlling weeds usually involves the help of several people. It involves awareness, detection, prevention, planning, treatment, coordination, and monitoring to solve the problem. Examples of invasive weeds include purple loosestrife (in the eastern and western United States); spotted knapweed (in the eastern and western United States), which can produce 1,000 seeds per plant and whose seeds can lay dormant for eight years; leafy spurge (in the northern United States), which has a powerful root system that can penetrate


25 feet deep (7.6 m); yellow star thistle (mainly in the western United States); dalmatian toadflax; garlic mustard, which threatens native spring wildflowers; Oriental bittersweet (in the eastern United States), which is a twining vine that can smother trees and saplings; water hyacinth, which clogs aquatic ecosystems; and melaleuca, a tree that has invaded the Florida Everglades (Source: Bureau of Land Management). The diversity of our native plant communities is decreasing as weeds are damaging the ecosystems. As native vegetation is reduced, so is the amount of forage available for wildlife and livestock.

Mapping and Interpreting the Land For anybody utilizing public lands for any type of activity—hiking, biking, hunting, fishing—being able to read topographic maps is an important skill. A topographic map informs the user about where things are and how to get to them. Topographic maps describe the shape of the land. They define and locate natural and man-made features like woodlands, waterways, important buildings, and bridges. They show the distance between any two places, and they also show the direction from one point to another. Topography (the slope of the land) is shown by contour lines. These are imaginary lines that follow the ground surface at a constant elevation; they are usually printed in brown in two thicknesses. The heavier lines are called index contours, and they are usually marked with numbers that give the height in feet or meters. The control interval, a set difference in elevation between the brown lines, varies from map to map; its value is given in the margin of each map. Contour lines that are close together represent steep slopes. Natural and man-made features are represented by colored areas and by a set of standard symbols on all U.S. Geological Survey (USGS) topographic maps. Woodlands, for instance, are shown in a green tint; waterways, in blue. Buildings may be shown on the map as black squares or outlines. Recent changes in an area may be shown by a purple overprint. A road may be printed in red or black solid or dashed lines, depending on its size and surface.

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a

b

(a) Topographic maps are useful for navigating the landscape. In this map, the brown contour lines indicate differences in elevation. Lines close together represent steep slopes. (b) The photo below illustrates the actual landscape the map is portraying. The conical mountain in the background is Reid’s Peak, which appears on the right side of the topographic map. (Nature’s Images)


Maps are made to scale; that is, there is a direct relationship (a ratio) between a unit of measurement on the map and the actual distance that same unit of measurement represents on the ground. If, for example, one inch on the map represents one mile (which converts to 63,360 inches) on the ground, the map’s scale is 1:63,360. A convenient way of representing map distance is through the use of a graphic scale bar. Most USGS topographic maps have scale bars in the map margin that represent distances on the map in miles, feet, kilometers, and meters.

Polluting Land Resources Unfortunately, humans’ use of the land over time has had negative effects, harmful to the health of the land. Different types of pollution include air pollution, the greenhouse effect, use of pesticides, poor municipal waste management practices, oil spills, and water pollution. The significant beginnings of air pollution started when people began burning fossil fuels. With the beginning of the Industrial Age, where coal was used to power buildings, equipment, and machinery, pollutants began to be pumped into the air, making it unhealthy to breathe. Added to this problem is the exhaust from the millions of cars on the roads each day, which pollute the air through their emissions created from burning petroleum. The problem began to escalate, which forced the federal government to begin monitoring and controlling pollution. Many industries were refitted with equipment to help reduce pollution, and cars were redesigned with better pollution control in mind. Although these measures have helped, pollution is still a problem, as evidenced by the greenhouse effect and the effects of acid rain. The greenhouse effect is what keeps the planet warm. Its natural existence is critical to life on Earth. When sunlight reaches the Earth, some of it is reflected back into space, but most of it travels through the atmosphere until it reaches the Earth’s surface. There, it warms up the land and the oceans, making the Earth give off energy as well. This outgoing—longer wavelength—energy is emitted back to the atmosphere,

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where it is absorbed by some of the atmospheric gases. The gases trap this heat, which warms the atmosphere, and keeps the Earth warmer. The natural occurrence of the greenhouse effect enables life to exist on most places on the Earth—such as the higher latitudes. In addition, without it, the world’s oceans would freeze over. This natural process has gone on throughout the history of the Earth. The problem begins, however, when humans pollute the atmosphere with carbon dioxide, methane, nitrous oxide, and other manmade gases, given off through the burning of fossil fuels. This raises the level of greenhouse gases and warms up the Earth’s surface to temperatures higher than would occur naturally. This resulting global warming can have long-term detrimental effects on the Earth’s climate and biodiversity. It has the potential to melt the polar ice caps, disturb sea levels, and change the natural balance of the Earth’s many interrelated biogeochemical systems. Another side effect of pollution is acid rain. Acid rain is produced when gases in smoke dissolve in droplets of airborne moisture. Although it is invisible, it is highly destructive. It can kill trees and fish. It can also erode and dissolve stone. Many of the limestone or marble statues in Europe and Egypt have been eroded over the years by acid rain, causing great damage to many precious cultural and historical pieces of outdoor art. Today, acid rain affects the health of many countries. Exhaust fumes from cars and factories are one of the biggest culprits. People can also breathe in tiny particles contained in the exhaust, which can cause respiratory (breathing) problems. Some large cities—like Los Angeles—are prone to high concentrations of these chemical pollutants; the murky brown layer associated with many large cities is known as photochemical smog. This causes many health risks for people with respiratory problems. One way to control this is by enforcing regulations that require cars and industry to develop cleaner, more efficient engines and machinery. Pesticides are chemical poisons, designed to kill plants and animals such as insects (insecticides), weeds (herbicides), rodents (rodenticides),


and mold or fungus (fungicides). They contain active ingredients, which are intended to kill the target, and inert ingredients. Pesticides are another pollutant that can affect the quality of the land. They also can have adverse health effects on people. They can be absorbed through the skin, swallowed, or inhaled. Once they are sprayed, they can stray from their point of application to settle on neighbors’ properties, toys, furniture, and pools. People and pets often walk through them and track them inside homes. Many scientists believe that less than 10% of pesticides used actually reach their target weeds. The rest runs off into water or dissipates in the air. Studies have shown that pesticides applied to landscaping can drift 12 feet (3.6 m) to 14.5 miles (23 km) from the site where they were applied, thereby polluting the land. A study conducted in Wisconsin even found traces of pesticides in several underground aquifers, leading to drinking water contamination. Other research has shown that several pesticides become more toxic as they break down. Many pesticides are used in farming. One problem with this is that pesticides can harm necessary soil microbes and beneficial insects and predators. In addition, the pests that are targeted can mutate to become more resistant to the toxin, so that either more has to be used or new types developed. For this reason, many farmers use other methods of pest control to keep from polluting the landscape, such as crop rotation (planting different crops each season that are associated with different pests so that the land cannot become infested) and biological controls (introducing beneficial insects or animals that eat the pests). Municipal solid waste—or garbage—is another environmental problem that pollutes the land. One of the biggest culprits in modern-day waste is the excessive amount of packaging that products are shipped in. This packaging—boxes, Styrofoam, and plastics—is only used one time, but its lifetime may be decades long because the materials are resistant to decay. Because bacteria cannot break down plastics, they never completely disappear. Plastic items often break apart, but the fragments that are left behind can last for hundreds of years. This

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type of waste adds to the huge mountain of garbage collected from cities and towns each day. Managing waste has become a global problem. Scientists estimate that every person in the United States generates up to one ton of household waste every year. In addition to plastics, household and industrial waste contains many different materials. Much of the municipal waste that is generated is buried in huge landfills, which create other environmental problems, such as toxic liquids that can seep into groundwater sources and rivers; toxic liquids can also give off toxic gases when the garbage begins to decompose. Landfills can also be harmful to wildlife. Birds, for instance, can become tangled in plastic bags and suffocate. They can also be killed if they get tangled in the plastic soft drink six-pack holders. For this reason, these plastic holders should always be cut apart prior to disposal so that wildlife cannot become entrapped. Another option for handling waste is to burn it; but incinerators can cause problems as well by releasing dangerous pollutants into the air. The most feasible solutions to problems with municipal waste are to use less packaging and to recycle materials. This benefits the environment in many ways. Reusing products keeps the waste out of landfills. It also conserves energy because it requires less energy to recycle an existing product than it does to create a new product from raw materials. The benefits of recycling, reducing, and reusing are discussed in greater detail in Chapter 9, which discusses future issues. Other environmental problems that pollute the land and damages natural resources are oil spills and leaks of hazardous materials. Accidents, spills, leaks, and past improper disposal and handling of hazardous materials and wastes have resulted in tens of thousands of sites across the United States that have contaminated the land, water (groundwater and surface water), and air (indoor and outdoor). These contaminants include petroleum products, industrial solvents, metals, bacteria, and radiological materials.


These contaminated sites can threaten human health as well as the environment, in addition to harming economic growth and the prosperity of local communities. In addition to the disposal and handling of nuclear waste from nuclear power facilities, there are also contaminants left as a result of uranium mining—particularly in the western United States. There are thousands of abandoned mines in the western states, from commodities such as silver, gold, copper, uranium, and many others, that have never been sealed off and reclaimed (cleaned up). With the increased pressure for multiple uses on the land in recent decades, such as recreational activities, many areas where these mines are located are dangerous. Not only may hazardous materials be present, but shafts (uncovered openings in the ground) also present a physical danger. Many government agencies—such as the BLM, Forest Service, and Environmental Protection Agency (EPA)—are currently in the process of inventorying and reclaiming these sites in order to make the public lands safe for multiple use activities.

Human Impacts on the Environment Humans have left their mark upon the land with many activities over the decades. As populations grow, impacts occur from urbanization, which adversely impacts wildlife habitat; logging and development, which promotes deforestation; agriculture and factory farming, which can degrade the quality of the landscape; mining, which can destroy and contaminate landscapes; and increased energy consumption, which increases pollution and accelerates land degradation. Human activities can have permanent impacts on fragile environmental ecosystems if the land and its resources are not well managed. Human population growth is the number-one threat to the world’s environments. Each person requires energy, space, and resources to survive. Unfortunately, this results in environmental losses. If the human population was not growing as fast, it might be possible for land-use planners to balance environmental losses with renewable resources

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and regeneration. In some areas of the world, however, populations are increasing faster than the landscape can sustain them. Cities are growing especially fast. Before the Industrial Revolution, most people lived on farms in rural areas. The beginning of industry enticed people to move to cities because this was where jobs could be found. Urban (city) living has a huge impact on the natural world because almost everything that people need has to be brought in from outside cities. Some of the world’s largest cities—such as Beijing, China; São Paulo, Brazil; Bombay, India; and Tokyo, Japan—have populations of more than 15 million people. These “mega cities” each take up hundreds of square miles of land. Suburbs (new neighborhoods just outside city limits) are also spreading rapidly. Unplanned housing often causes environmental problems. When housing spreads into the adjoining countryside, natural habitats are destroyed. Land development, urbanization, and other forms of habitat modification directly affect ecosystem health. Whole ecosystems may change or even disappear entirely. Land development can cause changes in freshwater delivery to an ecosystem, and runoff resulting from more paved roads and other impermeable surfaces can increase the spread of contaminants. The world’s population reached 6.1 billion in 2000. The United Nations projects that world population for the year 2050 could range from 7.9 billion to 10.9 billion people. There are several impacts on the environment from rapid population growth, including water scarcity, cropland scarcity, damage to fisheries and forests, global warming, and natural plant and animal species extinction. The more the human population grows, the more land that is needed. The end result, however, is that the land has to come from somewhere—and that land is usually habitat for other species. Some natural habitats are destroyed to make space for farmland; others for towns, cities, and roads; while others are destroyed so that the resources within them can be used, such as minerals, oil, or timber.


Wetlands are destroyed for agriculture and urbanization, which eliminates habitat for a multitude of migratory birds as well as the diverse species that live within them—many of which have become threatened or endangered species. Areas that are used for mining have their own unique impacts on the land. Mines can contaminate areas with toxic waste that, in turn, can destroy the surrounding habitat. Often, toxins can enter nearby water sources and contaminate streams and groundwater aquifers and harm nearby wildlife communities as well as people. Toxic mine drainage includes components such as sulfide compounds. These compounds can be converted by water and air into highly acidic solutions. These acids, in turn, can leach toxic minerals—such as lead, arsenic, and cadmium—out of the rock, to create an acidic and toxic mixture, which contaminates groundwater and surface runoff. This can devastate local fish, duck, and wildlife communities. Cyanide—an extremely toxic compound—is often used by mining companies to help in the extraction and refining of ore, which in turn produces large amounts of toxic waste that can cause long-term contamination of the land and water. Another environmental effect of mining is that some mine operations involve deep underground shafts, which require constant pumping of groundwater to keep the shafts dry. This can significantly drain aquifers and dry up nearby private and public wells. This also damages nearby lakes and streams that are dependent on groundwater recharge to maintain their current water levels. One of the most obvious environmental impacts of mining are the huge waste disposal pits. Mining produces large amounts of pulverized waste rock. Mining companies either create huge surface “tailing pits” or dump the pulverized waste back down the mine shafts when they are finished mining. Either way, this waste is generally acidic and toxic, which harms the environment. There are cultural effects associated with mining as well. Archaeo logical and historic sites can be dug up and damaged; economic

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upheavals can occur with the development of boom and bust mining towns (towns that are only used during the mining process, then are abandoned when the mining is completed); and loss of tourism if the natural beauty of the land is degraded by mining operations occuring nearby. Deforestation is another threat to the health of the land. Deforestation is the large-scale removal of forest, prior to its replacement by other land uses. Forests provide some of the richest habitats on Earth. For example, the areas in the world with the most plant and animal species are the tropical rain forests. In fact, scientists believe there are many species that have not even been discovered yet. This means that when forests are destroyed, species are becoming extinct before they are even discovered. Scientists believe that many species—known and unknown—in the rain forests may hold the cures to many diseases, such as cancer. Scientists believe that deforestation may also contribute to the regional and global climate imbalances. In addition, forests play a major role in carbon storage; with their removal, excess carbon dioxide in the atmosphere may lead to global warming. Factory farming is another use of the land that can have serious impacts. Factory farming is farmland that is consolidated into huge industrial operations, often housing thousands of animals. There are several adverse impacts to the land. Water pollution can be a severe impact. Huge amounts of manure are produced under concentrated conditions in most factory farms. This can be difficult to collect, store, and dispose of properly. Oftentimes, nearby streams and lakes can become polluted from excess nutrients, chemicals, and bacteria. Another drawback to factory farming is the severe odors that are generated. Large buildups of chemical gases are common, which pose a health issue. The noise and traffic of farm equipment and trucks can also degrade property values of the land nearby. Along with urbanization, there are impacts to the land from transportation and energy consumption. Huge tracts of land are cleared each year and used for transportation corridors when freeways are built. More highways encourage urban sprawl, which in turn destroys


Analyzing Land Use Change in Urban Environments Scientists today are becoming high tech in their approach to analyzing different types of land use. Using computers and the Geographic Information Systems (GIS), scientists can use historical and current existing data to build models, which allow them to evaluate potential land use change before it even occurs. The U.S. Geological Survey (USGS) Urban Dynamics Research (UDR) program is using historical maps, aerial photographs, and satellite images, along with other types of data, in a computer environment to analyze the effects of urbanization on the landscape and to model urban growth and land use change under different growth and development scenarios. They are then able to address issues like potential loss of natural vegetation and open space, decline in wetlands, and connectivity of wildlife habitat. Computer models use data such as urban extent, transportation routes, water features, other important land uses, topographic features, climate, supplies of water, and natural resources. Modeling different land use change scenarios helps many people make better-informed land use decisions that will affect the land on a long-term basis. For example, land use planners use this data to evaluate environmental impacts, delineate urban growth boundaries, develop land use zoning plans, and gauge future construction requirements. Hydrologists use these models to evaluate new water sources for future urbanization and to analyze water pollution. Geologists use them to evaluate the availability of building materials, such as sand, gravel, and cement, as well as to predict impacts of future natural disasters and the potential damage they may cause. Policymakers can then use these damage or hazard projections to direct future development away from the most at-risk areas. Biologists also use land use change data to compile maps on habitats, species distribution, and land management. Predictions about future urbanization are critical to the protection of ecosystems and the sustainability of communities.

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wildlife habitat. Associated with highways are increased water and land pollution from cars burning fossil fuels. As discussed earlier in connection with the results of overgrazing, desertification is a serious condition that can also result from other impacts on the land, especially in delicately balanced ecosystems. When human activity stresses arid land beyond its tolerance limit, the landscape can become degraded. This degradation of formerly productive land is a complex process. It can involve multiple causes, and it proceeds at varying rates in different climates. Desertification may intensify a general climatic trend toward greater aridity, or it may initiate a change in local climate. Desertification does not occur in linear, easily mappable patterns. Areas far from natural deserts can degrade quickly to barren soil, rock, or sand through poor land management. In fact, the presence of a nearby desert has no direct relationship to desertification. Scientists do know that increased population and livestock pressure on marginal lands has accelerated desertification, and goals today include understanding the desertification process better and taking better care of the land on a long-term basis to prevent environments from becoming degraded to the point where the land can no longer be reclaimed and made healthy again. As the human population continues to increase and subsequent demands on the land become greater, this problem will escalate unless better and more effective conservation methods are developed and used consistently.

CHAPTER

6

The Importance of Land Resources

T

he land offers a diverse array of natural resources. From access to clean drinking water to pristine vistas accessed through forest hiking trails to energy and mineral resources, the land contains a priceless reserve of resources that offer an abundance of goods and services. These resources, however, must be well cared for so that future generations can enjoy the same benefits from the land that people enjoy today. Oftentimes, the value of these resources is not recognized until the resource is hurt or destroyed. Too often, land managers and economists ignore the value of these resources, treating ecosystem goods and services as if they will always be in abundant supply. For example, loggers harvest trees because they provide goods for the construction industry, but loggers often ignore the value that the natural forest had by providing habitat to wildlife, water purification, and flood control. When this happens, goods and services derived from natural resources can jeopardize the same resources for other applications. Likewise, building 121

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towns and roads may have a distinct benefit to society but, in exchange, destroys the natural habitat that already existed there. There are always tradeoffs when changing the uses of land. Goods and services refer to many different aspects of land use. Some are tangible—they are easy to assign a dollar value to (such as lumber). Others are more abstract and difficult to assign a dollar value to (such as water purity and natural beauty—many people consider these priceless). Goods and services can refer to a wide range of resources, such as healthy biodiversity, soil fertility, agricultural productivity, clean water, abundant sea life and ocean resources, and abundant plant life to name just a few. Although the previous five chapters have already touched on many of the land’s goods and services—for example in relation to wetlands, rangelands, and deserts—this chapter focuses on the importance of the land’s resources in terms of goods and services by looking at forest environments, grassland resources, freshwater assets, coastal resources, urban environments, recreational and entertainment values, energy sources, mineral resources, and cave environments.

Forest Environments Forests are defined as land areas dominated by trees whose canopy covers at least 10% of the ground area. Forests cover about 25% of the Earth’s land surface, excluding Antarctica and Greenland. Many forests were impacted when people began clearing the land for agriculture. Fortunately, in the United States, most of the forests are managed. In tropical regions, however, deforestation (destroying the forests by cutting down the trees) is estimated to exceed 50,193 square miles (130,000 sq/km) each year. Forests, woodlands, and stands of trees provide food, fuel, filtered water, medicines, shelter, and building materials for construction. Many people in the world depend on the goods and services from forests for food (such as fruit, edible plants, nuts, and game). Timber, bamboo, and other vegetative matter are important in many countries for building and household materials. Industrial wood products contribute more than $400 billion to the global economy each year.

The Importance of land Resources

Forested areas are also used as fodder to feed livestock. Forests provide employment for many people through the food, wood fuels, and medicines produced from the forest resources. For example, wood fuels account for 15% of the primary energy supply in developing countries—and up to 80% in some sub-Saharan and Asian countries. Water filtration is a critical service that forests provide. In the United States, scientists estimate that national forests provide water to 60 million people in 3,400 communities. For example, in New York City, forest vegetation and soils are the primary or only filter for much of the water that the inhabitants of the city use. As seen in the carbon cycle described in Chapter 4, forests play a significant role and contribution to carbon storage on Earth. Scientists have determined that forests store 613–938 gigatons of carbon, which makes them an important natural defense against climate change. Forests also provide the mechanisms to support high levels of biodiversity. More than 60% of known terrestrial plant and animal species live in forests. It is the biological richness and beauty of forest ecosystems that holds tremendous appeal to many environmentalists and others who love nature. The biggest threats to healthy, productive forests are mining, logging, fragmentation by roads and buildings, and clearance for agriculture. The construction of roads in forests also makes it easier for hunters and poachers to gain access, which can deplete the wildlife and decrease the natural biodiversity, sometimes to the point of extinction.

Grassland Resources Many people in the world depend on grassland resources to feed their livestock, which then supplies them with many goods. Grasslands are also critical for providing living space for approximately 800 million people worldwide. Grasslands encompass the grasslands of Australia, the cerrado and campo of South America, the savannas of Africa, the prairies of North America, and the steppes of central Asia.

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Grasslands are highly dynamic ecosystems. They support plants, animals, and human populations worldwide. They also provide food, energy, carbon storage, biodiversity, habitats for endemic bird and wild herbivore species, and tourism. They recycle water and build and maintain soil stability by controlling erosion with their dense network of roots. Scientists estimate that grasslands cover from 31% to 43% of the Earth’s land surface. In central North America, tall-grass prairie has decreased almost 97% because it has been converted to urban and agricultural areas. Conversion to croplands and other agroecosystems has been the primary reason for the diminishing extent of grasslands globally. Grasslands provide many types of goods. Because their forage supports both domestic and wild animals, they provide food, serving as vital sources of meat, milk, and other products. Cereals as a food source are an extremely important good that grasslands supply. Crop grains such as wheat, rice, rye, and other major grains feed millions of people worldwide. Fuel wood and wind farms on grasslands are important sources of energy. As the demand for and price of oil increases, renewable sources of energy will become more common around the world, and grasslands will be key areas for these sources. Grasslands also offer diverse ecosystems. They comprise 35 of 136 terrestrial ecoregions identified as highly diverse ecosystems. Grasslands also store roughly 34% of the terrestrial global stock of carbon—most of it in the soil rather than the vegetation. Recreation and tourism is another service provided by grasslands. The most severe modification of grassland ecosystems is desertification. Sparse rain in arid grasslands makes them susceptible to damage from human management and slower to recover from degradation. Fire can also be destructive to grasslands. Although some natural fires can be beneficial by preventing bush encroachment, removing dry vegetation, and recycling nutrients, extensive burning can ultimately degrade grasslands. Overgrazing is also an important degrader of grassland condition, especially when too many animals are confined to small areas of


land, vegetation is sparse, and soils are eroded. In many regions of the world, overgrazing and drought pose a threat to the future health of the Earth’s grasslands.

Freshwater Assets Freshwater in the form of surface water is found in lakes, wetlands, rivers, streams, and brooks. Surface waters occupy only 0.08% of the Earth’s surface and account for only 0.01% of the Earth’s freshwater. More than 90% of the Earth’s freshwater is locked away in polar ice. In order to utilize what freshwater is available, dams and irrigation channels have been developed to transport freshwater to where it is needed. Canals and pipelines have been constructed to connect water basins to make it possible to transfer water between basins. In some instances, these activities have had a negative effect on natural ecosystems. For example, when wetlands are drained and the rivers feeding them are diverted, those essential areas lose their ability to control flooding, store carbon, and purify water. In the past 100 years, half of the world’s wetlands have been converted to either agroecosystems (farms) or urban areas. Groundwater—an important source of freshwater—is stored in aquifers, wells, and springs. Groundwater supplies drinking water to about 1.5 billion people. As use and demand for water increase, freshwater’s ability to maintain high quality and quantity can be adversely impacted. Increased demands from industrial production and agriculture are the main causes of freshwater degradation. Agriculture, by itself, uses nearly 70% of all the water that humans withdraw and is one of the heaviest polluters. While forests and grasslands filter and purify water, many of these ecosystems have already lost significant amounts of their vegetation, which is essential for water filtration. Freshwater resources provide several important goods and services. They provide water for human, agricultural, and industrial use as well as recharging aquifers. The fish caught from rivers, lakes, and wetlands provide a significant food source. Freshwater is also an important source of energy. Of the total amount of electricity

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g enerated globally, hydropower generated from the water stored in dams accounts for 18%. Freshwater environments support biodiversity. Of all animal species, 12% live in freshwater. All animals depend on freshwater for survival. Rivers and streams, along with plant life, provide waste removal as an important service by filtering pollution and maintaining water quality. Recreation is another valuable service. Fishing, swimming, and boating at freshwater sites provide employment and tourism opportunities. Scientists and environmentalists predict that water availability will be one of the major challenges facing humans in the twenty-first century. As the human population increases worldwide, the water available per person will decrease. If freshwater sources become polluted, that further decreases water available for drinking. Urban and industrial areas are at the greatest risk of contamination due to various chemicals and nutrients being added to the water supply. If freshwater becomes contaminated, it can cause algal blooms and oxygen depletion and impair the biological components of ecosystems. Freshwater is one of the Earth’s most critical resources.

Coastal Resources Coastal areas are some of the most popular areas for human inhabitation and recreation. In fact, about 39% of the world’s population lives within 62 miles (100 km) of a coastline. In addition, each year, millions of tourists vacation in coastal areas, such as Hawaii, the Caribbean, the South Pacific, Bermuda, and the east and west coasts of the United States. Coastal ecosystems are an important food source. Each year, millions of metric tons of fish and shellfish are harvested from oceans. They also play an important role as a natural filtration system. They maintain marine water quality by filtering pollutants from inland freshwater systems. They also store and cycle nutrients and help protect shorelines from erosion. Wetlands, mangroves, and sea grass beds filter or degrade toxic pollutants and absorb nutrient inputs. If these resources are removed, it can trigger harmful algal blooms.


Coastal environments also provide construction materials. Sand mined from riverbeds and lime extracted from coral is used to make concrete and cement. Many marine organisms provide antibiotics, anti-inflammatory, anti-tumor, and anticancer agents. Coastal environments support biodiversity by providing habitat for more than 250,000 species. They are also an asset for people because they provide employment opportunities in fishing, recreation, tourism, and other fields.

Urban Environments Urban environments contain more than just people. They also contain an abundance of plants and animals. In addition to homes, buildings, and roads, there are also more natural areas found in parks, yards, commercial landscaping, and undeveloped lots. Just like the individual factors in other ecosystems must work together in order to stay healthy, so must the components in urban ecosystems. For example, the trees and streams in public parks perform the same functions as trees and streams in forests, grasslands, and other ecosystems. Urban ecosystems differ from other ecosystems, however, in that they are usually highly disturbed systems and are subject to rapid change in soil and plant cover, as well as temperature and water availability. In addition, buildings, roads, parking lots, and other types of construction form an impenetrable covering of the soil that affects how water flows through the urban environment and determines what can live there. Plant life also differs in urban ecosystems. Because people like to landscape their yards and plant gardens, this environment contains many nonnative (nonnatural) yard plantings and weeds, many of them invasive species. Urban environments provide many valuable goods and services. They provide the bulk of employment opportunities, housing, transportation, educational facilities, hospitals, and many other components that promote commerce and industry. The urban green spaces—such as parks and gardens—provide shade and temperature control to help counteract the intense heat

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that cities generate in the summer—heat primarily due to the large heat-absorbing surfaces of buildings and asphalt, as well as the highly concentrated energy use. Gardens and parks also help filter air pollution. For instance, in a park, the leaf surfaces of trees can filter out as much as 85% of the particulates that cause air pollution. Trees and shrubs also help filter out noise pollution. A 98-foot (30 m) stand of tall, dense trees combined with soft surfaces can reduce local noise levels by 50%. Vegetation also helps restore some of the natural balance by buffering storm water runoff, absorbing pollutants, and recharging groundwater resources. Cities also support a wide variety of plants and wildlife. Urban wildlife can include animals like deer, chipmunks, squirrels, muskrats, beavers, raccoons, coyotes, foxes, mink, weasels, and bats. Parks and yards also play an important role to migratory birds by providing resting and feeding places. According to the U.S. National Park Service, almost one-third of urban residents in the United States participate in wildlife-watching activities within one mile (1.6 km) of their homes. Urban environments provide recreational, aesthetic, and spiritual values by providing parks, gardens, and other open spaces. Urban environments are also food sources. Many city residents grow food in their backyards, vacant lots, and small suburban farms. The greatest impact on urban goods and services is the intensive and rapid urban growth that in turn takes the land use away from forests, grasslands, wetlands, and other ecosystems, thereby impacting those environments. For this reason, it is important to plan and manage urban resources and growth in ways that have the lowest impact. For example, cities need tree-care programs, soil fertility assessment, pollution control, regulation of freshwater use, and provisions for the wildlife that also share these areas.

Recreational and Entertainment Value An extremely important aspect of land use is that of recreation and entertainment. For instance, recreation is one of the fastest-growing uses of the public lands, such as the national parks, the national forests, and


a

b

c

d

Some of the most spectacular landscapes and natural resources of the land are protected in U.S. national parks. (a) Yosemite National Park, California. (b) Rainbow Bridge National Monument, Utah. (c) Devils Tower National Monument, Wyoming. (d) Yellowstone National Park, Wyoming. (a, photo by J.A. Thomas, courtesy U.S. Geological Survey; b, c, d, courtesy U.S. Geological Survey)

other national recreation areas. These areas not only provide places for recreation and adventure, but also learning and quiet contemplation. Millions of people each year visit these areas in the United States to camp by pristine lakes, hike to the summits of mountains, houseboat on spectacular lakes, or work alongside professional archaeologists and historians. Forests and parks offer awe-inspiring landscapes and intriguing cultural sites. Many visitors hike, ride horses, camp, picnic, drive for pleasure, mountain bike, fish, enjoy educational activities,

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A multitude of land resources offer outdoor recreational opportunities. (a) A rock climber braves the sheer sandstone rock formations of the Colorado Plateau. (b) Backpacking opportunities are available on the public lands, which are gateways to some of the most spectacular geologic formations in the country. (c) Camping in the national forests is a popular pastime for many vacationers. (d) Fishermen try their luck at Flaming Gorge in Utah. (a, b, d, photos by Kelly Rigby, courtesy U.S. Bureau of Land Management; c, Nature’s Images)


watch wildlife, and participate in water sports. In order to protect these precious resources, responsible land management and good stewardship need to be practiced. Management of these resources will be discussed further in Chapter 7.

Energy on Public Lands Federal lands provide a substantial portion of the natural energy resources in the United States. According to the Bureau of Land Management, production from these sources amounts to nearly 30% of total annual U.S. energy production. Types of energy sources on public lands include oil, natural gas, coal, oil shale, and geothermal resources. The federal agency most responsible for the leasing of energy resources is the Bureau of Land Management. They have the important role of maintaining U.S. supplies of conventional energy resources. Because of the growing U.S. demand and increasing public unease with dependence on foreign oil sources, pressure on the public lands to meet energy demands is intensifying. These lands, however, are available for energy development only after they have been evaluated through a land-use planning process. If development of energy resources conflicts with management or use of other resources, development restrictions may be imposed, or mineral production may be banned altogether. Mineral Resources The comfortable existence that people enjoy today depends on the abundant use of mineral resources from the land. Almost everything we use—from pencils to computers—is made from materials that have been extracted from the Earth. Minerals are used in many products, some of them surprising. For example, aluminum baseball bats are derived from bauxite ore. Aluminum bats are popular because they are light, durable, easy to use, and usually send a baseball further than a wooden bat. A metal bat temporarily flexes when used to hit a ball; it then springs back, transferring more energy to the ball than a rigid wooden bat.

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Various aluminum alloy bats were introduced in the 1990s. The most successful of these was the scandium-aluminum bat. Scandium is a mineral that, when alloyed with aluminum, greatly increases the strength and resilience of the aluminum without adding to the weight. Scandium occurs in minute quantities in more than 800 minerals and is usually obtained as a by-product of refining uranium. Bicycle frames are another product made from mineral resources. They can be made of steel, aluminum, carbon fiber, magnesium, or titanium. The material that the bicycle is made out of is determined by the intended use of the bicycle, such as for on-road or off-road riding, and the cost of the material. Each of these materials has specific characteristics that behave differently under certain conditions. The mineral used is determined by the manufacturer’s specifications for density, stiffness, elongation, tensile strength, fatigue strength, and toughness. Clay sports surfaces are also derived from minerals. Clay is used on baseball and softball fields in the base paths, batter’s boxes, bullpens, pitcher’s mounds, and practice areas. Clay and clay composites are also used on tennis courts, horseshoe pits, track-and-field event areas, and on horse-racing tracks and bridle paths. Today, these clay surfaces are comprised of a mixture of clay, sand, and silt. Another improvement in the evolution of field clay is calcined clay, which is clay that has been heated in a furnace at about 2,000°F (3,632°C). Once calcined, the clay is ground into a powder that readily absorbs water, reduces soil compaction, and will not stick to cleats or hooves. Along with this process, flakes from the mineral vermiculite that have gone through the process of exfoliation—a rapid heating process similar to the one for calcined clay—is also produced and sold as kitty litter. For body builders and strength-training athletes, the free weights used—barbells and dumbbells—are made of a steel bar with rubbercoated disks of different weights. Dumbbells are usually made of cast iron or steel, although they are coated with vinyl or other materials to protect their surfaces.


The sport of golf also utilizes minerals. The shafts of clubs today are made of aluminum or titanium instead of wood. Metal shafts give the golfer better control over the ball and the ability to hit it out of difficult situations. With innovations of the twentieth and twenty-first centuries, clubs are being made of graphite, titanium, beryllium, copper, aluminum, carbon fibers, steel, tungsten, and alloys of these and other lightweight metals. Today, companies are experimenting with new alloys and other materials and new designs to make clubs lighter, stronger, more flexible, and add other characteristics that can help both professional and amateur players improve their game. The extraction, processing, and transport of minerals, however, inevitably impacts the environment. Controlling the disruption of landscapes and ecosystems, while providing supplies of critical minerals, can be a challenge. There are a number of environmental issues associated with mining and mineral extraction. Extracting minerals from the surface of the Earth or below the surface requires moving large amounts of earth. For example, extracting one ton of copper requires moving and processing roughly 350 tons of ore. Although law requires reclamation of land disturbed by mining operations, some disturbances are permanent. Processing of minerals creates a waste stream that must be carefully controlled to avoid leakages into surrounding ecosystems. In some areas, old mines abandoned before the beginning of strict regulations are still a problem today. In many cases, the companies that operated these mines are no longer in existence, making it difficult to assign the responsibilities of cleaning up the site. One major problem is acid mine drainage, especially from abandoned mines. In fact, some mines dating from Roman times are still producing acid drainage. Acid mine drainage comes from pyrite or iron sulfide in the ground. When disturbed by excavation, this material weathers and reacts with oxygen and water to produce high levels of iron and sulfate in runoff water. Modern mining operations use lime and other chemicals to treat the acidic drainage, but this method has not been in existence long enough to determine its long-term effectiveness.

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The Hidden Wonders of Caves A cave is any naturally occurring void, cavity, recess, or system of interconnected passageways beneath the surface of the Earth. Caves make underground landscapes diverse and fascinating and are rich in resources. They host some of the largest springs and most productive groundwater reservoirs on Earth. In fact, most of the drinking water in the United States is stored naturally in cave-bearing rocks, such as limestone. Limestone is an ideal rock for cave formation because it is highly erodible by water. A total of 175 different minerals occur in limestone caves, a few of which are only found in caves. Most mineral deposits in caves are made of calcium carbonate (CaCO3). The most common cave mineral is calcite; aragonite and gypsum are also common. Calcite is what most of the speleothems—cave formations—are composed of. Aragonite crystals in caves can be blue, green, white, or brown. Gypsum can be tinted a variety of colors. Scientists have determined that gypsum was mined from Mammoth Cave in Kentucky centuries ago, possibly for the medicinal value of the sulfates it contains, similar to Epsom salts. More than 40 of the known cave minerals contain phosphorus. The phosphorus in these minerals comes from guano (bat droppings), which was the most highly rated fertilizer in the nineteenth and early twentieth centuries. The most common mineral resources from caves are quarried rocks. Limestone, dolomite, marble, gypsum, travertine, and salt are all mined in large quantities throughout the world. Caves also provide a unique subsurface habitat for rare animals. Caves preserve fragile archaeological and paleontological materials for thousands of years. Our present knowledge of the early development of human beings and their cultures is closely associated with the exploration and study of caves. People have long used caves as dwelling places, burial sites, storehouses, and ceremonial palaces. Many skeletal remains of primitive relatives of Homo sapiens have been found in caves in Africa and Asia. Many artifacts are extremely well preserved in the constant environments of caves. Scientists date flowstone in caves using


uranium-series techniques, which is helpful for determining the ages of artifacts in relation to the flowstone. Caves also provide rich information about paleontological resources in two ways. First, fossils are preserved within cave-forming rock. Caves may provide the best or only exposure of subsurface bedrock, and fossils preserved within the cave-forming rock may become exposed through cave-forming processes. Second, fossils accumulate within cave features. Openings in the ground surface such as caves attract and trap animals. Rich deposits of fossil bone can accumulate as remains associated with organisms inhabiting the cave or can be transported there. Predators frequently transport prey into caves and create piles of bones. In addition, pack rats are responsible for the redistribution of fossil material while building and dismantling their nests in shelters such as caves. These accumulations of bone and plant material, called middens, are important sources of paleontological data for researchers.

Especially for Human Cave Visitors Caves can be exciting and fun to explore using very simple equipment. But caving can also be dangerous. Each person must be aware of his or her own safety and the protection of things inside the cave, too. The following are some important caving safety rules: • Always tell someone where you are going and when you plan to return. • Never go caving alone. • Go with an experienced caver, preferably someone who is familiar with the cave you will be exploring. • Take at least three light sources, with extra batteries and bulbs. • Remember that cave environments are very fragile. Even slight disturbances can harm cave creatures. Source: Bureau of Land Management

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a

b

Speleothems are visible in many caves throughout the United States. The different cave formations include spires, pearls, columns, and many other fantasy-like shapes. (a) This cave in Carlsbad Caverns is known as the Chinese Theater. (b) Spelunkers, such as this woman, are people who enjoy exploring wild, undeveloped caves. (Photos courtesy National Park Service)


Throughout history people have used caves for many purposes— from guano mining to tourism. In addition, caves’ natural beauty and opportunities for adventure and exploration are valuable services. Because of their constant temperatures, people have used caves to store food, such as potatoes and apples. Caves have also served as subsurface farms for mushrooms, rhubarb, and celery. People have used caves to store cheese during the aging process. Wines and beers are also aged in caves. The blue penicillin mold in Roquefort cheese develops only in a cool, wet atmosphere, such as a cave. In fact, penicillin was originally developed in the caverns below Roquefort, France. Tourism in caves is big business. In the United States alone, more than 150 caves are open to the public, and several million visitors pass through each year. Many of these caves are lighted and host wellmaintained trails, such as those at Mammoth Cave in Kentucky and Carlsbad Caverns in New Mexico. Caves like this, which are used for tourism, are called “developed” caves. “Wild” caves remain in their natural state and provide spelunkers (cave explorers) unique opportunities for adventure. Caves present beautiful environments, often with large arrays of stone formations called speleothems—moon milk, soda straws, cave bacon, cave flowers, draperies, flowstone, frostwork, columns, cave balloons, cave pearls, helictites, cave popcorn, stalactites, and stalagmites. These stone formations exhibit bizarre patterns and otherworldly forms, which give some caves a wonderland appearance. Animal life also inhabits caves and provides rich data for biologists to study. Cave animals fit into three categories: trogloxenes, troglophiles, and troglobites. These categories are based on the amount of time cave animals spend in caves. •

Trogloxenes are cave visitors or temporary cave residents. They move freely in and out of caves. Bats are the bestknown trogloxene. Others include skunks, raccoons, pack rats, moths, frogs, beetles, some birds, and even people. They are not dependent on caves for their survival.

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•

•

Troglophiles love caves. They normally live in the dark zones of caves, but they can and do survive outside of caves, provided the environment is moist and dark. Earthworms are a good example, as well as salamanders, beetles, and crustaceans (such as crayfish). Troglobites are life-forms that live permanently in the dark zones of caves. They cannot survive out of the cave environment, and they have developed special adaptations from living their entire lives in caves. Because food sources in caves are meager, the sensory organs and physical adaptations of troglobites are devoted to sustaining energy and finding food. Most troglobites are white to pinkish in color. They lack pigment (color) because they have no need for protection from the sun’s rays. Many troglobites have no eyes or have eyes that are poorly developed.

Human impacts can threaten the health of cave resources. Humans can alter the surface water flow patterns, pollute the water, change cave airflow patterns, introduce foreign and harmful elements into caves, and disturb cave biota (life). Care must be taken around cave resources so that they do not become damaged or ruined. Many caves still need to be explored in order to further understand their unique resources and role in the landscape.

CHAPTER

7

Management of Land Resources

J

ust as the future success of a personal business depends on how well it is managed, so does the land and its varied natural resources. Because the landscape has such diversity, it is sometimes difficult to manage one resource without compromising another. For example, at a recreational area, some visitors may be interested in the solitude of a hike in a quiet, pristine area accompanied only by the babble of a brook and the call of a solitary eagle circling overhead. Others may be more interested in driving those same trails quickly on a motorized four-wheel off-highway vehicle (OHV). Still, others may elect to ride mountain bikes; and others, horses. Because there are so many potential uses of the land—such as wildlife habitat, water quality, plant habitat, recreational activities, extraction of minerals, harnessing of energy resources, and archaeology, just to name a few—managing the land can become a difficult balancing act. Land managers must not only know what resources the land has to offer, but also understand those uses both in terms of potential use 139

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and potential conflict and how all the resources interrelate. Since the principle goal of a land manager is to preserve, protect, and utilize the resources in the best way possible, they must be extremely cautious to avoid using one resource to an extreme, while harming others. It is a cause-and-effect relationship that requires a well-based knowledge of multiple-use strategies. These ideas not only apply to personal landowners, but also to the various government agencies in the United States that must manage millions of acres of land as efficiently and intelligently as possible. This chapter looks at what goes into responsible land management and the challenges that managers face today. First, it examines the role of the federal government and how they collectively manage the millions of acres of forest, parks, and open range in the country every day. Next, it will focus on human impacts on land use and why land stewardship is critical. This chapter then takes a look at how important the multiple-landuse concept is when applied to the vast, open areas of public lands. It takes a look at the practical aspects of managing and the latest hightech methods that are available for land managers and scientists to use today. Finally, it will look at land-use planning and how every person can contribute toward a healthier environment.

The Role of the Federal Government—Forests, Parks, and Open Range It is the mission of the various government agencies—U.S. Forest Service (USFS), National Park Service (NPS), Bureau of Land Management (BLM), and U.S. Fish and Wildlife Service (FWS)—that deal with managing land to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations. All American citizens own this land—all 550 million acres. Of these 550 million acres, the BLM takes care of more than half of it—264 million acres. Most of the federal lands are found in the western states and Alaska. The BLM also manages the underground mineral wealth of 700 million acres across the country.

Management of land resources

The scientists and land managers of the federal government must take care of the plants, soil, water (which provide homes for wildlife), and the wildlife itself, such as sheep, wild horses and burros, elk, moose, bear, wolves, birds of prey, and fish. They also manage the archaeological (past civilizations) and paleontological (past life, such as dinosaurs) resources. Scientists have found fossils of all sorts of dinosaurs on public lands and signs of many other creatures, as well. Prehistoric rock paintings across the desert landscapes tell of ancient peoples that

Bureau of Land Management Facts • The Bureau of Land Management (BLM) is responsible for managing 264 million acres of land—about one-eighth of the land in the United States—and about 300 million additional acres of subsurface mineral resources. The BLM is also responsible for wildfire management and suppression on 388 million acres. • Most of the lands the BLM manages are located in the western United States, including Alaska, and are dominated by extensive grasslands, forests, high mountains, Arctic tundra, and deserts. • The BLM manages a wide variety of resources and uses, including energy and minerals; timber; forage; wild horse and burro populations; fish and wildlife habitat; wilderness areas; archaeological, paleontological, and historical sites; and other valuable examples of our natural heritage. • The BLM administers public lands within a framework of numerous laws. The most comprehensive of these is the Federal Land Policy and Management Act of 1976 (FLPMA). All BLM policies, procedures, and management actions must be consistent with FLPMA and other laws that govern use of the public lands. Source: Bureau of Land Management

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inhabited the area hundreds, if not thousands, of years ago. These areas are cultural and historical treasures that need to be protected and cared for so that future generations will also be able to enjoy them. Different people enjoy public lands for different reasons. Spending time on public lands allows people to get close to nature by observing wildlife and native plants. Others like to raft on rivers, and some people like to visit ghost towns, prehistoric sites, or dinosaur tracks. Some people enjoy the outdoors by riding their mountain bikes on trails through the forest or desert. Campers, hunters, rock climbers, cross-country skiers, horseback riders, off-road vehicle fans, and snowmobilers all come to enjoy the public lands throughout the year. People use federal lands in other ways, too. Miners mine coal, gold, silver, and minerals, as well as sand and gravel. Ranchers use the grasses and shrubs to feed their cows and sheep. Timber companies harvest trees. Towns can obtain land for parks and schools. Native Americans are able to carry out their traditions on public lands, where they gather special foods—such as pine nuts—or materials to make crafts. The federal government also fosters partnerships with communities and individuals. Working partnerships allow communities to become involved in multiple-use management for commercial activities, recreation, and conservation.

Human Impacts on the Land Every time humans use a landscape, they impact it in some way, whether for good or bad. Some of the harmful impacts caused by people include overfishing, overgrazing, abandoned mine sites, spills of hazardous materials, erosion, road construction, excess waste, degraded water quality, and the introduction of invasive weeds. Fishing is central to the livelihood and food security of 200 million people—especially those in the developing world. One out of five people on Earth depend on fish as their primary source of protein. According to the United Nations, aquaculture—the farming and stocking of aquatic organisms including fish, mollusks, crustaceans, and aquatic plants—is growing more rapidly than all other animal foodproducing sectors.


But even though aquaculture may be increasing, statistics also reveal that global main marine fish stocks are in jeopardy, increasingly pressured by overfishing and environmental degradation. This depletion of fisheries poses a major threat to the food supply of millions of people. Many experts believe that Marine Protected Areas (MPAs) need to be established in order to conserve fish stocks and allow dwindling fish populations to increase. According to the United Nations Environment Programme’s (UNEP) World Conservation Monitoring Centre in Great Britain, less than 1% of the world’s oceans and seas are currently MPAs. The magnitude of the problem of overfishing is often overlooked in comparison to other areas of environmental concern, such as deforestation, desertification, energy resource exploitation, and decreasing biodiversity. The rapid growth in demand for fish and fish products is leading to fish prices increasing rapidly. This, in turn, has encouraged more people to start fishing businesses because they find the potential income to be attractive. More than 70% of the world’s fisheries are overexploited and unsustainable fishing threatens the economy and traditional livelihoods of communities everywhere across the world. In the last decade, in the North Atlantic region, commercial fish populations of cod, hake, haddock, and flounder have fallen by as much as 95%. Some ecologists have recommended zero catches to allow for regenerations of stocks. As outlined in Chapter 2, overgrazing is another impact brought on by people putting more animals on the land than the land can support. A major problem stems from the fact that when animals graze, the grass plant is severely impacted; and what these plants need is sufficient recovery time between grazing periods. Just a few animals at a time are capable of overgrazing plants to the point of death. Increasing the area available to the animals is not nearly as effective a solution as shortening the time period during which the plant is exposed to grazing. When grass is allowed to recover and grow before it is grazed upon again, it will have longer roots, making the plant healthier and better able to recover, grow, and thrive. In order to enable this to happen, good land management techniques, such as rotating livestock

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through different fields to graze, are required—otherwise desertification will result. Abandoned mines are another significant human impact on the land. During the early days of U.S. mining, thousands of mines— especially in the western United States—were dug and opened to find and extract rocks, ores, minerals, coal, and other commodities. Once either the resources had been depleted or the mining companies went out of business, thousands of mines were left abandoned. Abandoned mines pose a threat to water quality (mines can leak hazardous materials, which can contaminate nearby streams and other water sources); safety (many mines have open holes in the ground that people can accidentally fall into); and the ecological health of an area. In the past ten years, the federal government has begun a comprehensive program to reclaim (clean up and restore) these lands. These reclamation programs are prioritized based on the mine’s effects on water quality and public safety. When a mine site is reclaimed, generally the open mine is sealed off, and the ground and water sources nearby are cleaned up. Hazardous material spills are also a problem on public lands. Both commercial and illegal activities have led to releases of hazardous substances and creation of hazardous waste sites. The Bureau of Land Management reports that more than 60% of all hazardous waste sites on public lands result from commercial uses. Landfills, mines, and mill sites account for almost half of these; airstrips and oil and gas sites make up the remainder of the hazardous waste sites arising from commercial activities. Illegal activity (trespass dumping) is responsible for almost 40% of all hazardous waste sites discovered to date. The federal government land management agencies engage in hazardous material emergency response actions, site evaluations, and prioritization of cleanups in accordance with laws and regulations. This involves working with the Environmental Protection Agency (EPA), state environmental quality departments, counties, and potential responsible parties (both public and private) to fund and accomplish the cleanup of hazardous sites. As of September 30, 1997, there were 1,698 sites for which cases had been opened and which were actionable under the


Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), commonly referred to as the Superfund. Erosion control—whether natural or human-induced—is critical to the successful management of land resources. There are several methods of land recovery and erosion control. One way to control erosion is to establish wetlands. Wetlands treat wastewater and runoff, help reduce flooding, provide diverse habitat, and prevent erosion. Over the past decade, several different approaches have been used to construct wetlands to stabilize stream banks and reduce the impact of floods. Hydro seeding and hydro mulching are used for soil erosion control and slope stabilization in areas that are steep, remote, and hard to get to. In this process, a helicopter drops hydro-seeding and hydromulching liquid solution on the land, where it covers the ground and encourages vegetation growth. It can also be delivered from a hose spray system on a truck, which may be used to seed large areas next to freeways. Another method of soil erosion control on slopes is to place coarse netting along the surface of the ground, where it is secured with ground staples. This helps hold the soil in place, keeping the necessary nutrients at the site of the plant so that it will grow. As soon as plants begin growing, their root systems become better developed and also serve to hold the soil in place. The construction of roads disturbs local ecosystems. When a road is constructed, it can indirectly cause erosion problems. Because it disturbs the landscape, road construction can also take away resources previously used by native plants and animals. Roads increase traffic and congestion in the area, further impacting wildlife. In many areas, dozens of animals get hit and killed on roadways by cars and trucks each year as they attempt to cross the road to find food, water, shelter, and breeding grounds. With roads also come urbanization, which can further impact wildlife because of the congestion and alternate use of the land. Waste management is an important impact issue that affects the landscape. The table on page 147 lists some of the waste materials that can negatively impact the land.

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In order to control pollution and environmental damage from various wastes, a number of methods are available, such as recycling programs; land disposal guidelines; and facilities for treatment, storage, and disposal of waste products. Water quality can also be degraded due, directly or indirectly, to human impacts. Activities that can degrade the quality of natural water resources include mining, agriculture, raising livestock, construction, and hazardous material spills. Once water becomes contaminated, it is oftentimes very difficult to restore to its original condition. Polluted water harms people, animals, plants, and the important cycles that govern the natural processes on the landscape, such as the hydrologic (water) cycle. As seen in a previous chapter, the introduction of invasive species—such as weeds—is another environmental impact brought on, or propagated by, human’s use of the land, which in turn harms the environment for native plants and animals. Invasive weeds usually come from other countries or regions. They spread rapidly and can do a lot of damage, especially to the native plants (those plants that grow naturally in the area). Invasive weeds also have special characteristics that help them get a head start on native plants. Many have a long root system, which makes it easier for the plant to get water. Many weeds are tall and bushy and have hundreds of seeds. The seeds can travel great distances by wind, water, or they can “hitchhike” on wildlife, horses, livestock, and people. Some invasive weeds grow tall quickly and keep the sun from reaching smaller, slow-growing native plants. Still others grow in dense patches, crowding out native plants. Not only do weeds damage native plants, they can endanger wildlife and livestock that depend on the native plants for food and shelter; they increase soil runoff into streams, which can harm fish; they absorb more water, thereby taking water away from native plants; they increase the problem of wildfires, because they burn better and faster; and they cause problems for hikers and animals who come in contact with thorny or poisonous plant parts.


Waste Materials That Impact the Health of the Land • • • • • • • • • • • • • • • • • • • • •

Residential waste materials Backyard burning Batteries Household hazardous waste Medical waste Municipal solid waste (garbage) Fertilizers Herbicides Commercial/industrial waste materials Batteries Cement kiln dust Construction and demolition Debris Crude oil and gas waste Fossil fuel combustion waste Industrial waste Medical waste Mining Mineral processing Scrap tires Used oil

Land Stewardship Land stewardship is simply taking care of the land in such a way that the natural plants and animals thrive, water remains clean, soil is stable, and all conditions needed to maintain the land are in a healthy state for people to enjoy now and in the future. Land stewardship requires careful, well-thought-out planning and management. With proper land stewardship, open spaces are developed to meet the needs of expanding communities—both human and wildlife. Currently, not only are federal government agencies working toward land stewardship, but so are state and county government agencies,

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universities and other research entities, and private companies and citizens. In order for land stewardship to be effective, it takes the combined efforts of all these endeavors. Shoreline and desert environments are some areas that have been reclaimed through the use of good land stewardship. Proper management has successfully stabilized shorelines and deserts. Estuaries and shorelines are reclaimed to protect the land from flooding and control erosion. Coastal dune formation is encouraged by placing an obstacle in the path of the prevailing wind, which causes it to slow down and deposit some of the sand that it is carrying. The obstacle is sometimes a fence, but usually is a plant. Sometimes a film of rubber compound is applied to stabilize the sand enough to allow the germination and growth of grasses. Once dunes begin forming, adding nitrogen fertilizer to the sand can increase their stability. Shrubs are then planted, which, over time,

Help Wanted! Invading plants are costly to remove or control. That is why land managers need your help to prevent them from getting started in the first place. Check with a local naturalist or conservation organization to find out which invasive weeds are threats in your area. To help, do the following: • Leave the plants alone, and report all sightings to local extension agents, land managers, rangers, or conservationists. • Remove all weed seeds from clothing, shoes, pets, camping gear, and tire treads. • Don’t pick wildflowers or any plants. They could be invasive weeds just waiting to be spread. Source: U.S. Bureau of Land Management


increases the nutrients and biomass of the soil. Once this is achieved, trees can be planted that can tolerate the salt spray and winds from the ocean. The challenge of desertification is faced in a similar matter. Desertification can be reduced by effective use of the land resources from the individual level upward, the introduction and improvement of proper irrigation methods, increased soil moisture storage capability, the restoration of degraded pastures, and the improvement of strategies of pasture rotation. Sometimes, introducing forage plants for stabilizing the soil stabilizes deserts. Plants help control erosion by reducing wind speed along the surface of the ground and protecting the soil from drying out and shrinking. They also add nutrients to the soil to increase its fertility. Riparian areas also require careful management. They are the green, moist areas next to a lake, stream, or river where plants grow vigorously. Riparian areas are especially important in dry climates. The water itself and the plants along the shore attract many different kinds of animals. The plants also help prevent erosion, which occurs when soil washes into the water. A healthy riparian area helps keep the water clear and cool for fish and other aquatic animals. In several places—especially in the western United States—riparian areas have been damaged. Trucks have been driven through streams, or roads have been built too close to the water. Logging and mining operations and other industrial activities have also been harmful to large areas surrounding streams; so have poor farming practices. In some places, too many cows or sheep graze nearby. Other popular activities, such as camping, boating, hiking, and biking have also weakened stream banks. All of these activities can destroy plants along the stream and cause stream banks to cave in. Erosion gets worse because there are fewer plants to hold the soil when it rains. The water becomes muddy. It also makes the area warmer because there are no trees to shade the water; and warm, dirty water can harm the native fish. In many locations, people are working to repair damaged riparian areas by planting trees along stream banks and moving roads away

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from the water’s edge. They are also building fences to control livestock grazing near streams. Slowly, with good management practices in place, many mismanaged riparian areas are beginning to recover. With responsible management plans in place, areas will be less prone to degradation.

Managing the Public Lands Because there are such a wide variety of resources on the land, the balancing act of managing them can be a challenge for land managers. Even though there are many individual facets to the land, it is important to look at the big picture when developing workable management plans. Land managers and scientists must look at the big picture, because everything is related—every living and nonliving thing is connected in an ecosystem. Because the conditions of the natural world are always changing, effective land managers must also monitor these changes and occasionally adjust their management plans to encompass the change. As populations increase in the western states—which are where most of the public lands are—more demand is put on the land for multiple use. Along with these uses is an increased demand on the land for recreational activities. In fact, today, two-thirds of the public lands in the lower 48 states are within an hour’s drive of a large city or growing community. The public lands have become the West’s backyard, providing one of the last guarantees of open space. Public lands provide visitors with a diverse array of recreational activities, such as hunting, fishing, camping, hiking, horseback riding, boating, white-water rafting, hang gliding, off-highway vehicle and pleasure driving, mountain biking, birding and wildlife viewing, climbing, winter sports, and visiting natural and cultural heritage sites. Mining and minerals constitute a major use of the land. The public lands offer an array of fluid minerals (petroleum, oil, and gas) and solid minerals (coal, oil shale, tar sands, gold, silver, copper, and many others). Mineral resources are valuable because they keep the country


running smoothly. From computers to toothpaste, almost everything contains minerals—and some of them most likely from public lands. Much of the coal that is used to generate electricity every day also comes from public lands. Managing all the mineral resources is a huge endeavor. From a management standpoint, mineral extraction can be difficult because the process of getting them out of the Earth can damage the land and water and create other hazards. Because of this, the BLM must make sure that mining companies follow strict rules that help protect the environment. Companies have to plan their operations carefully, choose the least damaging mining methods, and repair the land after. Some of the biggest hazards come from mines that are no longer in use. Abandoned mines pose safety hazards to people visiting public lands. People can get lost or trapped, be overcome by poisonous gases, or fall down a mineshaft. Abandoned mines may also leak dangerous materials into the land and water for years. Part of the Bureau of Land Management’s strategy is to clean up and close down abandoned mines. In the meantime, visitors to the public lands should stay out of them. Renewable resources that must be properly managed and cared for in a multiple-use setting include wildlife, threatened and endangered species, wilderness areas, fish, forest, and rangeland. Forests constitute some of the most valuable land areas. They do more than just provide trees and wood for people. When forests are managed properly and kept healthy, they provide habitat for wildlife, plants, and fungi. Healthy forests have healthy streams that are home to fish and other aquatic life. They also provide people with the chance to enjoy nature. A healthy forest has many different species of trees growing in it— both young and old trees. A healthy forest even has logs on the ground and standing dead trees, called snags. Many fungi and mosses live on these dead trees. A good mixture of trees and other plants means a variety of animals will be able to live in the forest. The food, water, and shelter that animals need to survive can all be found in a forest, if the

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a

b

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d

Recreational areas on public lands need careful land management in order to stay healthy and be available for everyone to enjoy. Recreational activities that may harm the land if not properly managed include: (a) mountain biking among archaeological petroglyphs, (b) camping and fishing, (c) biking, and (d) dune buggy driving. (Photos courtesy of the Bureau of Land Management)


Wildfires threaten many areas, especially the forests of the western United States. Wildfires can be started naturally from lightning strikes or unnaturally through the careless actions of humans. (Natural Resources Conservation Service)

forest is healthy. Over years of experience, forest managers have learned how to keep forests healthy. Managers also know that building roads in forests can cause problems. Roads are put in forests for many reasons—to allow loggers to bring in large trucks to haul away cut timber; by mining companies to build the structures associated with mining; and by recreational enthusiasts in order to access campsites, boating sites, and hiking trails. Roads, however, can cause serious erosion. When the eroded soil enters clean streams, it can harm fish and other creatures that depend on clean water for their survival. More traffic and people on forest roads disturb wildlife. Public land managers must work hard to protect wildlife habitat—sometimes by

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removing some of the forest roads. When reclaiming the land from old road use, the roadbed is dug up, then the area is replanted with a variety of seeds and seedlings. The wildlife on open ranges must also be managed. Two groups of wildlife on public lands in the west are wild horses and burros. Today, more than 40,000 wild horses and burros make their homes on public lands. These animals are the descendents of animals that escaped from, or were set free by, early explorers and settlers in the region. The land managers of the Bureau of Land Management protect them because they consider them “living legends” of our country’s history. It is illegal to harm them; but because they have few natural enemies, there is a danger that their numbers will grow to the point where the land cannot support them. They also have to be managed so that they do not over compete with other species of wildlife and cattle for food and water. Land managers use several techniques to keep the sizes of the herds under control. Sometimes, the animals are gathered and moved to another area, either for a short or longer time, to what are called

Important Fire Rules and Facts • Make campfires only in designated areas. • Never leave a campfire unattended. • Always keep water near a campfire. Put out a campfire by following these simple steps: 1. Drown the fire with water. 2. Use a stick to mix the ashes with the soil. 3. Scrape and chop partially burned sticks. 4. Add more water. 5. Stir with the soil again. Source: U.S. Bureau of Land Management and National Forest Service


“ holding facilities.” Some animals are also adopted out to qualifying, loving families for a small fee. Recreation represents a huge demand on the land, and the trend is on the increase—more people visit public lands than ever before. There are many recreational activities for people to enjoy—hiking, biking, camping, fishing, and riding OHVs represent just a few of the recreational activities available to visitors on public lands. Wildfires are another reason to carefully manage the land. With the increasing trend of visitors each year to public lands, the risk of accidentally set wildfires gets extremely high in July and August, especially in the West, where the grasses from spring growth dry up and die. Wildfires can be both good and bad, depending on the fire. In nature, fires in forests and grasslands can be useful. In fact, some fires are needed to keep the land healthy. Fires in nature do not always burn with huge flames and great heat. Such smaller fires clean out leaves and dried grass that have built up over the years. They help recycle dead plants, releasing nutrients into the soil. The nutrients help new grass and other plants to grow. Many animals like to eat the tender, nutritious plants that return after a fire. Some plants actually need fire. Certain pinecones will not open and drop their seeds without the heat of a fire. Fires can also kill insects that harm trees. Even burned, dead trees are places where birds can nest or sit and watch for prey. In order to keep the land healthy, trained fire specialists sometimes set fires—these are called “prescribed burns.” In order to set a prescribed burn, conditions need to be just right, so that the fires do not get out of control. Fires started in the wrong conditions without planning, or through carelessness, can spread quickly and do a lot of damage before they can be brought under control.

Modeling, Managing, and Planning In order to manage land—whether it is small parcels or large areas—it is important for the manager to understand the geographic area as well as all the components within the ecosystem and how they relate

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to, and depend upon, each other. With the development of computers and sophisticated software over the past few years, modern technology has enabled scientists and managers to build mathematical and virtual models to represent landscapes and the systems that function on them. Computer modeling can help unravel the complex relationships so that land managers can not only manage the land at the present time, but also project into the future and be able to create long-term management plans. These computer models involve extremely intricate mathematical equations and solutions; many involve complex mathematical algorithms and statistical analyses. Models can answer questions and provide guidance in such fields as forest development, logging management, engineering planning (such as for campgrounds, rest stops, hiking trails, boat docks, and other recreational developments), inventory analysis, ecosystem analysis, forest health analysis, terrain stability determination, archaeological study, fishery plans, wildlife habitat, and recreational development and monitoring. Geologists use models to locate potential mineral deposits; hydrologists are able to model flow and surface water quality, as well as perform watershed analysis; oceanographers can model ocean currents and their effects on the landscape; seismologists can create models to predict where earthquakes, landslides, or floods are likely to occur; geomorphologists can model the effect of erosion and sedimentation on the land; wildlife biologists can model wildlife habitat; and firefighters and ecologists can model wildfire patterns and the various effects from wind, terrain, and vegetation. In fact, modeling can be done for anything of interest to scientists and land managers. The more scientists learn, the more sophisticated the models become. Scientists who build these models must have a detailed understanding of both the terrain and the systems that affect them (such as the hydrologic cycle); the life-forms (plants and animals) within the system and their functions; the physical and geologic processes that occur (such as erosion, deposition, and the nitrogen cycle); weather patterns; and a host of other physical phenomena. The more data input a model


has, the better it is able to represent reality, and the more useful the model is. With models, cause and effect scenarios can be developed so that managers can analyze the possible short- and long-term effects and consequences of their decisions on the landscape. In this way, fewer mistakes are likely to be made that could harm the environment. Models help create better short- and long-term management plans.

Geographic Analysis and Mapping—High-Tech Tools to Help Land Managers Because of all the decisions that land managers must make and all the issues they must take into consideration, land management can quickly become overwhelming. Fortunately, technology has advanced far enough that tools have been developed to handle large amounts of interactive data. A significant addition to the science of mathematical modeling is the use of the rapidly evolving technologies of Geographic Information Systems (GIS), remote sensing technology (using satellite imagery), and real-time monitoring. A Geographic Information System involves a powerful, complex, computer database that organizes information about a specific location. It creates a computerized map with a potentially unlimited amount of information available for every location. Each category of information is called a “layer” or “theme.” One advantage of GIS over paper maps is that many more layers can be stored and easily displayed in various combinations. The real strength of GIS lies in its potential to assist scientists and land managers in analyzing data and making informed decisions. Stacking themes or layers of information allows new patterns to emerge for scientific consideration. When information concerning different resources—such as wildlife, minerals, plants, hydrology (water), and soils—is entered into GIS, managers can look across disciplines and see the “big picture.” For example, endangered species habitats can be seen along with standard hydrology and vegetation maps. GIS technology is used by resource managers for a number of purposes such as determining suitability of an area for wildlife habitat, mapping areas at risk for

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fire, or assessing the health of rangelands and riparian areas in order to manage the health of wildlife. Another advantage of GIS is its ability to show changes over time. By comparing old data with new data for the same location, it is possible to see which areas have changed and been impacted the most. Trends can also be projected into the future. In southern California, support for managing commercial development in San Diego and Los Angeles to protect rare desert species was boosted when the public was able to see—through GIS modeling—projected results of development trends over time. This resulted in the protection of more than 81,000 hectares of desert habitat. As GIS technologies become more accessible, land managers increasingly use GIS to make decisions and communicate with the public. GIS allows people to see data at both large and small scales. This information allows scientists to create models that will show effects of different actions over time, illustrate long-term trends, and predict future conditions. To many, GIS technology alone has changed the way natural resource decisions are made. GIS and mathematical modeling go hand in hand for many applications. For example, before wildlife habitat sites can be planned for and protected, the areas need to be identified. An effective and highly advanced approach to this with GIS is called habitat modeling. In order to create a working model, scientists and land managers must identify all the factors involved, such as food availability, vegetation cover, forest type, topography, water resources, distance from urban areas, presence of roads, elevation of the land, and slope of the mountains. Once this data is collected and digitally entered into a GIS system, the resulting model can identify the most suitable habitats. Data—such as soil types—can be digitized from existing soil survey maps, satellite imagery can be used, and Global Positioning Systems (GPS) can collect data in the field. The data can then be entered as layers into the GIS model and used to create habitat maps. Using a combination of data layers, a skilled GIS analyst can identify both areas of likely habitat and areas not compatible with the specific wildlife being studied.


Maps and products associated with these efforts assist natural resource biologists, watershed scientists, county planners, policymakers, and concerned citizens by providing consistent information. The information helps decision-makers at both regional and local levels to answer questions, produce products, and provide information, including developing and depicting a broad range of conservation strategies for fish and wildlife habitats. From endangered species to erosion processes, it is becoming increasingly more difficult to monitor and manage landscapes over a wide area without the use of GIS. Many different types of models can be created using different combinations of the data layers. Which model is created is determined by which questions conservationists and land managers need to have answers for. By modeling vegetation types in GIS, scientists can gather a lot of information about wildlife habitat. When vegetation that an animal likes is found in an area where that animal lives, that area is more likely to be the animal’s natural habitat than an area that does not. Vegetation information is always an important layer in modeling wildlife habitat because vegetation is important for not only food, but also shelter and protection. GIS fire modeling analyzes the potential of vegetation to burn, which is also called fire fuel loading. During wildfires, many components affect the way a fire can be predicted to behave, such as humidity, wind speed and direction, and type of vegetation and its dryness. Field modeling is important for wildlife habitat so that managers can predict which areas are safest for wildlife. Habitat modeling is done to predict wildlife species distribution across landscapes. Models can predict the presence or absence of a species, its range, and the populations of species at different locations. Each model—along with the layers used in GIS—is specific to the species being studied. Wildlife biologists use the species distribution and density measurement to determine how healthy the ecosystem and its biodiversity are. Habitat GIS modeling is critical for studying threatened and endangered species. Habitat can be modeled for an

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abundance of species, such as bear, wolves, moose, birds, antelope, elk, and deer. Watershed modeling in GIS is used to study, predict, and control erosion of the land after fires, sedimentation, and flooding. Treatment modeling is used to monitor the land and attempt to manage wildfires. For areas that are overgrown, a prescribed treatment may involve thinning the natural vegetation or conducting a prescribed burn. GIS modeling can also be used during restoration after a wildfire when areas are being managed by reseeding. Reseeding is a conservation measure that helps keep invasive species from over competing with native species and taking over their habitat. Reseeding also provides habitat, food sources, and protection for wildlife. These GIS models are powerful tools that enable scientists, conservationists, land managers, and the public to work productively together to better manage the land’s ecosystems. Another tool is remote sensing: the collection and measurement of information by a device not in physical contact with what it is observing. Common remote sensing devices include eyes, cameras, binoculars, microscopes, telescopes, video cameras, and satellites. Input from remote sensors—usually aerial photos taken from an airplane or images acquired from a satellite—provide important information to a GIS in order to help land managers made decisions. Remote sensing imagery can be a very effective tool because the cameras and satellites they were taken from can “see” much better than people can. These remote sensors collect a broad range of electromagnetic energy, the energy that comes from the sun to the Earth, and is composed of several different wavelengths. The shortest wavelengths in the electromagnetic energy spectrum are gamma rays, X-rays, and ultraviolet rays. Humans cannot see this energy. As the wavelengths get longer, visible light occurs. These are the wavelengths that the human eye can see, but it is a very tiny portion of the entire spectrum. Visible light can be broken into blue, green, purple, yellow, orange, and red light.


Wavelengths that are larger in size than those of the visible spectrum cannot be seen by the human eye. These longer wavelengths include infrared radiation, microwave radiation, and radio wavelengths. Scientists refer to these various groups of wavelengths as bands. Even though the human eye cannot see much of this energy, remote sensing imaging systems can. This ability to see multispectral (multiple band) energy allows remote sensors to have greater capabilities than our eyes. For example, the green visible band allows people to analyze vegetation; short thermal wavelengths allow scientists to tell the difference between tree and plant species; thermal wavelengths help locate objects that are warmer than their surrounding environment (such as wildlife or lost hikers); and longer reflected infrared bands enable geologists to look at rocks and find mineral deposits. Computer software—called image processing software—is used to analyze remotely sensed images because it can see those subtle differences that the human eye is unable to see; therefore, image processing software can supply meaningful information that no other analytical method can provide. The computer can enhance, evaluate, and identify features based on principles of contrast and texture. It can also display the image in multiple classes based on the multispectral range. It can look at different combinations of spectral bands to show highly diverse information. The information gathered using computer software can be put into a GIS in order to inventory a landscape, model processes on the landscape, identify areas where significant change has occurred, map off-highway-vehicle damage, detect invasive weed species, measure forest biomass and amounts of timber, study trends of dwindling open space, monitor deforestation, map fuel buildup and fire dangers on the landscape, map existing vegetation, and help land managers make responsible short- and long-term decisions. Remote sensing provides scientists important land information, as well. It is useful for geologic applications, such as identifying the physical and chemical properties of rocks, understanding the relationships

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between plant cover at the Earth’s surface and the structure of underlying rock, studying faults, drainage systems, coastlines, and mountain systems. It helps botanists study plant distribution and land cover. It can help forest managers to enact fire response plans based on the type and health of the vegetation, and it can help farmers know when to plant crops and monitor the moisture conditions of their fields. It can help hydrologists study water bodies, rivers, streams, and understand environmental effects from things like drought and pollution. It also assists land-use planners in making wise decisions concerning land use, urbanization, and environmentalism. Another method land managers use to model the landscape and make quick decisions is through real-time monitoring and reporting. This is the process of gathering information through periodic or continuous measurement in the field to provide a view of current conditions. This data can then be used in a GIS environment to solve specific land resource issues. Real-time data can be collected for water resources, volcano hazards, landslide hazards, earthquake hazards, groundwater and surface water issues, precipitation monitoring, flood hazards, water quality issues, drought monitoring, and stream flow monitoring. Real-time data is generally used for rapidly evolving, time-sensitive environmental land issues. Because computers can be used to create products that are used to make many field data visits and do tedious interpretation and mapping, they allow managers to make timelier, more efficient, and effective decisions. Computers also allow for the development of much more sophisticated and accurate data to be compiled into maps, which helps scientists and land managers understand the processes on the land better. Special maps, called thematic maps, can be created for a broad spectrum of applications. They can be used to map management plans, forest development, logging plans, engineering developments, inventory resources, ecosystems, forest health, terrain stability, archaeological and paleontological sites, fisheries, wildlife habitat, and recreation plans. Spatial analysis and modeling can be done to create analytical


and predictive mapping, predictive ecosystem mapping, and planning for the short- and long-term. One tool that has been developed by the United States Geological Survey (USGS) to help land managers is the National Map. This data provides public access to high quality, geospatial data and information from multiple partners to help support decision-making by resource managers and the public. With this, the USGS provides geospatial data to enhance America’s ability to access, integrate, and apply geospatial data at local, national, and global scales.

Resource Decision Making: Land-Use Planning Good land management practices follow land-use plans that have been carefully thought out. Because land can be used in many ways, it is important for managers to identify what those uses are and develop plans so that the uses are compatible with each other without hurting the environment. For public lands, the federal government works with other groups that also have land in the same area, such as local, state, and tribal governments, the public, local user groups, and industry. When different groups own land within an ecosystem, it is important that these groups work out appropriate multiple-use rules together that are compatible and geared toward the health of the land. Land-use planning is the primary method used to establish the balance between land use and resource protection. Well-crafted plans are designed to protect present and future land uses and identify management practices needed to achieve desired conditions. Land-use plans are used by managers and the public to accomplish the following: • • •

Allocate resources and determine appropriate multiple uses for the land. Develop a strategy to manage and protect resources. Set up systems to monitor and evaluate the status of resources and effectiveness of management practices over time.

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Land-use plans are developed using an interdisciplinary approach that considers competing values and uses and weighs long- and shortterm benefits. They are usually prepared in conjunction with an analysis of environmental impacts to increase public understanding of the decision-making process and identify consequences of the plan. By enacting an effective land-use plan, it is possible to sustain the health, diversity, and productivity of the land for the use and enjoyment of present and future generations. A GIS is a vital tool in all land-use planning efforts because all information is tied to the land in some way. When managing lands, it is important to collect, analyze, and utilize spatial information that is related to, or describes, the type of land, the resources that it holds, and its spatial relation to the land around it. In an increasingly electronic and interactive world, maps and the tools used to create and analyze them play a crucial role in planning efforts—especially through the use of a GIS. A GIS serves a critical function in land-use planning because it allows managers to acquire, organize, document, maintain, and professionally analyze information on a wide range of topics and then communicate this knowledge to others via cutting-edge communications and visualization techniques.

Doing Your Part There are things we all can do to help care for the lands we visit. By acting responsibly, land managers can do a better job protecting the environment. According to the U.S. Forest Service and the Bureau of Land Management, you can do the following: • •

Plan ahead and prepare. Know the rules and learn about the area you’ll be visiting. Travel and camp on hard surfaces. Using hard surfaces prevents damage to soil and plants. Hard surfaces are established trails and campsites, rock, gravel, dry grasses, and snow.


•

•

•

•

•

Dispose of waste properly. Use trash cans for your garbage. If you are visiting an area where there are no trash cans, then take all trash away with you, including leftover food, litter, and toilet paper, in a sealed plastic bag. Human waste should be buried in a small hole 6–8 inches (15–20 cm) deep and at least 200 feet (60 m) from water, camp, and trails. Leave what you find. Leave rocks, plants, arrowheads, and other objects so that others can enjoy them, too. Do not build structures or dig trenches. Be careful with fire. Use a lightweight stove for cooking and enjoy a candle lantern for light. Where fires are allowed, use fire rings that are already there and keep fires small. Only use sticks from the ground that can be broken by hand. Be sure to burn all wood and coals to ash, put out campfires completely, and then scatter the cool ashes. Respect wildlife. Watch wildlife from a distance and do not follow or approach animals. Never feed animals. Control pets at all times, or better yet, leave them at home. Be considerate of others. Respect other visitors and remember that they want to enjoy the outdoors, too. Take breaks and make camps away from trails and other visitors. Let nature’s sounds—not radios or music players—be the ones heard. Avoid loud voices and noises.

When managers and users of the land follow the same guidelines and ethics, it makes managing the land both a short- and long-term success for everyone.

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his chapter presents issues centering around the conservation of natural land resources—not only in large open areas of public land, but also on private land and even backyards. First, it will address conservation of ancient places and why that is important; then it will outline the federal government’s “Leave No Trace” program and how it applies to all lands, both public and private. The chapter then visits the nation’s protected areas—the national parks, monuments, reserves, refuges, and wilderness areas—and explores the rare wonders they have to offer. Finally, it looks at conservation in action and how it can apply to everyone’s own backyard.

Conserving Ancient Places—Paleontology and Archaeology Many areas on public land contain fossils of dinosaur bones or tracks. If found, they should be left in place; the person making the discovery should also notify the land management agency responsible so that the 166


resource can be protected and preserved. Many of the fossils on display in museums came from public lands. Scientists consider the discovery of fossils a valuable find because fossils contain a great deal of information about ancient climates and landscapes. For example, through the study of fossils in the western United States, scientists have been able to determine that there was once a deep ocean where deserts are today. Fossils of sea creatures have been discovered in rock formations on the desert mountains. Fossils are one of the best clues scientists have as to how life developed on Earth. That is why it is important to protect and preserve these ancient treasures. Archaeology also provides important information about past human civilizations. Archaeologists study a site and look at all the things people left behind. They keep detailed records about everything they find and handle ancient objects very carefully. They put together hundreds of clues to get the whole story. According to the Bureau of Land Management (BLM), sometimes when visitors to the area discover a find—such as an arrowhead or pottery—they are tempted to take their find with them. There are so

Making a Good Impression It takes just the right conditions over a long period of time for fossils to form. To begin with, the remains of dead plants and animals have to be buried fairly quickly—oftentimes under mud or volcanic ash. Once buried, the remains have to stay undisturbed for a long time. It might take centuries for remains to become petrified. This occurs when living material is replaced by dissolved minerals, which then harden. Fossils can also form by the mold-and-cast process, which occurs when sediments around an object harden. When the object decays, an empty space, or mold, is left. If the mold fills with other sediments, which then harden, a cast is formed. Source: Bureau of Land Management

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many archaeological sites on public lands that it is an impossible task to watch over them all. People take things, such as arrowheads, pieces of pottery, carvings, and other artifacts. Sometimes people take them because they do not know any better; but sometimes visitors steal them either to add to their private collections or to sell them in the black market for antiquities. The biggest tragedy when this occurs is that clues to the past have been destroyed and lost forever. Today, stealing artifacts from public lands is a federal crime.

The “Leave No Trace” Concept The “Leave No Trace” program, adopted by the federal government and private organizations, is designed to educate outdoor recreation enthusiasts and build awareness of the environment and land stewardship. Its goal is to avoid, or minimize, impacts to natural area resources and help create a positive recreational experience for all visitors. This program is important because America’s public lands are a finite resource whose social and ecological values are linked to the health of the land. Today, land managers face a constant struggle in their efforts to find an appropriate balance between programs designed to preserve the land’s natural and cultural resources and provide high-quality recreational use. The Leave No Trace educational program is designed to teach visitors low-impact care of the environment. If visitors follow the program’s guidelines and act responsibly when using the land, then more direct regulations will not be necessary, such as restricting the number of people who can visit a particular area at a time or having to police the public lands. The Leave No Trace program stresses the following actions in order to maintain the beauty of the land: LEAVE NO TRACE! Before You Go: 1. Obtain information about the area and use restrictions. 2. Plan your trip for “off season” or nonholiday times. If this is not possible, go to less popular areas.


3. Choose equipment in earth tone colors: blue, green, tan, etc. 4. Repackage food in lightweight, burnable, or pack-out containers.

On Your Way: 1. Stay on designated trails. 2. Do not cut across switchbacks. 3. When traveling cross-country, hike in small groups and spread out. 4. Do not get off muddy trails. 5. Avoid hanging signs and ribbons or carving on trees to mark travel routes. 6. When meeting horseback riders, step off lower side of trail, stand still, and talk quietly. While You Are There: Campsite: 1. In high-use areas, choose existing campsites. 2. In remote areas, choose sites that cannot be damaged by your stay. 3. All campsites should be at least 75 paces from water and trails (200 feet). 4. Hide camp from view. 5. Do not dig trenches around tents. 6. Avoid building camp structures. If temporary structures are built, dismantle completely before leaving. Campfires: 1. For cooking, use lightweight gas stove rather than a fire. 2. In areas where fires are permitted, use existing fire rings. 3. Do not build new fire rings. 4. Do not build fires against large rocks. 5. Learn and practice alternative fire-building methods that Leave No Trace!

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6. Use dead and down wood, no larger than the size of your forearm. 7. Do not break branches off trees. 8. Put fire completely out before leaving (cold to the touch). Sanitation: 1. Deposit human waste and toilet paper in cat holes. Cat holes are 6 to 8 inches (15 to 20 cm) deep and should be located at least 75 paces from water or camp. Cover and disguise cat holes when finished. 2. Wash dishes, clothes, and yourself away from natural water. 3. Cover latrine and wash water holes thoroughly before breaking camp. 4. Pick up all trash and pack it out (yours and others). Courtesy: 1. Avoid loud music and voices or other loud noises. 2. Keep pets under control at all times. Better still, leave them home. 3. Leave flowers, artifacts, and picturesque rocks and snags for others to enjoy.

Before You Leave: Take one last look at where you have been and do your best to—Leave No Trace! Source: U.S. Bureau of Land Management, U.S. Department of Agriculture, the National Outdoor Leadership School, and the Boy Scouts of America. Use: Courtesy of Bureau of Land Management.

Protected Areas—National Parks, Monuments, Reserves, and Refuges Humans have had, and are continuing to have, a variety of negative impacts on the environment. Around the world, large areas of natural vegetation have been modified or destroyed in order to make way for


houses, roads, crops, and grazing animals. Many areas have had their natural drainage patterns altered, huge dams constructed on them, fire regimes changed, and large quantities of natural products—such as timber—harvested from them. These activities have left the natural environment in a very fragmented state. In order to minimize human impacts and protect the natural environment, it is necessary to establish conservation reserves such as national parks and monuments, nature reserves, and wildlife refuges. The purpose of these preserves is to provide protection for the full range of characteristics present in the natural environment. The preserves strive to protect the community of species, including their populations and diversity, to ensure their long-term survival. These special conservation areas preserve not only the beautiful scenery, but protect the animal life, plant species, and water quality of the areas as well. Every year, more preserves are established worldwide to protect biomes as people are becoming more aware of the importance of environmental conservation. The history of the national park system in the United States can be traced back to 1864, when Congress donated Yosemite Valley to California for preservation as a state park. Eight years later, in 1872, Congress reserved the spectacular Yellowstone country in the Wyoming and Montana territories to be set aside as a place where the American public could visit and enjoy its natural resources. With no state government there yet to receive and manage it, Yellowstone remained in the custody of the U.S. Department of the Interior as a national park—the world’s first area so designated. Congress followed the Yellowstone example by creating more national parks in the 1890s and early 1900s, including Sequoia, Yosemite (to which California returned Yosemite Valley), Mount Rainier, Crater Lake, and Glacier. In the late 1800s, there was also a growing interest in preserving prehistoric American Indian ruins and artifacts on the public lands. Congress first protected Arizona’s Casa Grande Ruin in 1889; then in 1906, it created Mesa Verde National Park, which contained dramatic cliff dwellings in southwestern Colorado, and passed the Antiquities

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a

b

Parks and preserves help maintain the quality of the landscape. (a) Grand Teton National Park in Wyoming is a national treasure. (b) The Florida panther is a critically endangered species. This panther lives in the Florida Panther National Wildlife Refuge. It is estimated that there are fewer than 50 of these animals remaining. (a, National Park Service; b, courtesy of the U.S. Fish and Wildlife Service, photo by George Gentry)


Act authorizing U.S. presidents to set aside ancient structures and other significant objects in federal custody as national monuments. Theodore Roosevelt used this act to proclaim 18 national monuments while he was the president. By 1916, the Interior Department was responsible for 14 national parks and 21 national monuments but had no organization to manage them. On August 25, 1916, President Woodrow Wilson approved legislation creating the U.S. National Park Service (NPS) within the Interior Department, giving the service responsibility for the national parks and monuments. In managing these areas, the Park Service was directed to protect the natural scenery, historic objects, and wildlife so that people today and in future generations could enjoy them. Today, the NPS is responsible for nearly 80 million acres of public land. The NPS preserves and protects some of the world’s most scenic and important natural resources. Park managers maintain ecosystem integrity in the approximately 270 national park system units that contain significant natural resources. In order to accomplish this, the NPS inventories the biological and geophysical natural resources, conducts long-term monitoring programs, develops management actions, and enacts plans to preserve the land’s resources. The NPS is also actively involved in protecting and restoring the resources. The national parks and preserves are not without problems, however. In many areas, national park system units represent the last vestiges of once vast, undisturbed ecosystems. Yet, more than 315,000 acres in 195 parks have been disturbed by modern human activities, including abandoned roads, dams, canals, railroads, grazed areas, campgrounds, mines, and other abandoned sites. In addition, exotic plants infest nearly 2.6 million acres in the national park system, reducing the natural diversity of these places. The variety, scope, and complexity of park resources and the disturbances occurring in them requires sophisticated knowledge of how natural systems work and what does and does not harm them. They also require expertise to apply this knowledge and provide environmental leadership.

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The NPS also provides the public with opportunities for enjoyment and ways to learn about the land’s resources. Through educational programs, referred to as interpretation, the NPS has become a significant resource for learning about the interconnections of human culture and nature, natural systems, the values of America’s diverse heritage, and the principles of democracy. The U.S. Fish and Wildlife Service is another government agency that protects the lands and their resources and supports land stewardship through their Wildlife Refuge System. They support Aldo Leopold’s (who is considered to be the father of wildlife ecology) teachings that land is a community of life and that love and respect for the land is an extension of ethics. They believe that wild lands and the support of diverse and abundant wildlife are essential to the quality of American life. Management, ranging from preservation to active manipulation of habitats and populations, is necessary to achieve Refuge System and U.S. Fish and Wildlife Service goals. Wildlife-dependent uses involving fishing, wildlife observation, photography, interpretation, and education, that when compatible, are central to the Refuge System. The NPS also supports International Biosphere Reserves, a working program to promote global conservation. Biosphere reserves are internationally recognized terrestrial and coastal or marine areas where management seeks to achieve sustainable use of natural resources while ensuring conservation of the biological diversity of the areas. The first biosphere reserves were designated in 1976 as part of the United Nations Educational, Scientific, and Cultural Organization’s (UNESCO) Man and the Biosphere Program (MAB). Biosphere reserves are nominated by national governments for inclusion in the world network of biosphere reserves. Each nation’s sites remain under the sovereign jurisdiction of the nominating country. Today, 47 biosphere reserves are recognized in the United States, with 23 of them involving 30 units of the national park system. For example, Channel Islands National Park was designated an International Biosphere Reserve in recognition of its genetic diversity and importance as an environmental baseline for research and monitoring.


Designated Wilderness Areas One method of conserving and protecting plants, wildlife, and other resources is by designating large areas of land as wilderness. Two hundred years ago, before roads, trains, telegraphs, farms, ranches, and mining camps, most of the western United States was wilderness. By 1964, the American people realized soon there would be no more natural lands left in the country. The Wilderness Act was created to save the last of the remaining wild lands from development. President Lyndon B. Johnson signed the Wilderness Act on September 3, 1964. It established the National Wilderness Preservation System to “. . . secure for the American people of present and future generations the benefits of an enduring resource of wilderness . . .” Wilderness areas can be designated by various government agencies throughout the United States, such as the National Forest Service and the BLM. When land is designated as having wilderness potential, it is because the land displays some type of unique characteristic, such as rare plant species, unique animal species, unique ecosystems, or geologic and environmental beauty. The wilderness areas that have been created by the federal government not only protect the biological diversity, but they preserve the beauty and historical perspective of the land. The wilderness program is an effort to preserve the land and its natural integrity in order to ensure the area is kept as pristine as possible. According to the BLM, wilderness areas are undeveloped lands that are meant to retain their primeval character. They are protected and managed in order to preserve their natural condition. These lands contain features of scientific, educational, scenic, and historical value. Wilderness areas are different from other areas of public land, such as national forests and national parks. Motor vehicles cannot be taken into wilderness areas so that the natural processes and peace of the land are not disturbed (with the exception of vehicle use needed for emergencies involving the health and safety of people). Wilderness areas are also off limits to potentially invasive and destructive activities such as mining. Invasive activities, like mining, can threaten the quality

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of water, recreation, and wildlife habitat. Even though visitors cannot drive through designated wilderness areas, there are many recreational activities that are permitted, such as fishing, hiking, horseback riding, backpacking, camping, nature study, photography, and rock climbing. These are areas where people can go to experience the full effects of nature without human interference. Wilderness areas also provide the peace and solace animals need in order to function and survive in their native environments. Although most of the designated wilderness lands exist in the western portion of the United States, there are also several designated areas in the East. Being protected by wilderness keeps critical habitat areas from being developed and exploited for their natural resources.

Conservation in Action The Earth has a finite amount of land, with many different factors constantly at work on it, such as climate, temperature, moisture, soil type, topography (slope and landforms), technology, economics, development, population distribution, and natural resources. Care of the land is often a delicate balancing act involving natural ecosystems and biodiversity. If the land is not properly cared for and wise management techniques employed, the land’s fertility and usefulness may be damaged or destroyed. For example, soil-forming processes are so slow, and the nutrient cycle so delicate, that environmental damage can have effects for many generations. Because of this, conservation of the land’s resources is important, not only now but for the future. Conservationists have developed several ways to manage the land and provide for the soil, water, plants, and animals. Previous chapters have already presented many of them: soil conservation (originating from the Dust Bowl experience of the 1930s); erosion control; desertification management; multiple-use management of the public lands; land stewardship; designation of protected areas such as national parks, refuges, and wilderness areas; and conservation of ancient places. Farmers play an especially important role in the conservation and fertility of the soil. Farmers can practice conservation using the


a

b

c

d

Examples of conservation in action. (a) A conservationist examines range grasses with a landowner and his son. (b) Conservationists examine plant life and water flow in a stream in which they hope to reintroduce a native species of trout. (c) Alternating strips of alfalfa with corn on contours protects this crop field in northeast Iowa from soil erosion. (d) A landowner checks a birdhouse in a restored wetland area. (a, c, photos by Tim McCabe, NRCS; b, photo by Ron Nichols, NRCS; d, photo by Gary Kramer, NRCS)

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contour strip cropping method. Here, various row crops, like hay or small grains, are tilled and planted side by side across slopes so that they follow the contours of the land. When farming is done on the contour, it creates small ridges that slow the runoff of water so that it has time to infiltrate the ground and also filter sediments. This reduces soil erosion. Landowners can also participate in wildlife habitat and ecosystem restoration, such as providing birdhouses in wetland areas so that both local and migrating birds can have a food source and a place to rest. Another important component of conservation is the development of recovery plans. Recovery plans are put in place to save endangered species. The U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration are two federal government agencies charged with the administration and implementation of the Endangered Species Act. The ultimate goal of the Endangered Species Act is the recovery of listed species and their associated ecosystems to levels where protection under the Act is no longer necessary.

Backyard Conservation One way everyone can help with the conservation effort is to create a backyard natural habitat. By choosing native plants that are suited for the area, little maintenance, chemical fertilizers, herbicides, or additional watering is necessary for the plants to remain healthy. It is not only less work to have a natural habitat, but it is better for the wildlife that lives there. This appreciation of nature and the land is often referred to as “backyard conservation” and can be done by anyone to conserve and improve natural resources on the land and help the environment. Backyard conservation is popular with inhabitants of cities and suburban areas. Many residents enjoy gardening, landscaping, and the pride of producing on their land, whether it is fruits and vegetables or beautiful flower gardens and landscaping. Many cities also strive to beautify the environment by creating large tracts of land devoted to parks, horticulture, and beautiful gardens.


Whether people have acres of land in the country, an average-sized suburban yard, or a tiny plot within the city, they can help protect the environment and beautify their surroundings. Backyard conservation provides habitat for birds and other wildlife, healthier soil, erosion control, water conservation, and nutrient management. The following conservation practices are popular and easy for anyone to do.

Backyard Ponds and Wetlands Backyard ponds and water gardens are not only beautiful, but provide habitat for birds, butterflies, frogs, and fish. A backyard pond doesn’t need to be big—it can be as small as 3 to 4 feet (1 to 1.2 m) wide. Backyard ponds are usually built where they can be seen from a deck or patio. Landscaping around the pond provides shelter for wildlife. The pond must be made with a protective liner in order to keep the water from seeping into the soil. Many people use pumps and filters in their ponds and build waterfalls on the side that cascade into the pool. They also put fish in the pond for additional habitat and aesthetic enjoyment. Fish also keep insect populations under control. Plants can be used in the pond environment. A combination of emergent, submergent, and floating species can be used. Emergent plants are those that have their roots in the water but their shoots above the surface. They are found on the margins of the pond. Examples of emergent plants are cattails and water lilies. Submergent species are those that remain underwater. They are often used as oxygenators. These plants remove carbon dioxide from the water and add oxygen. They also help keep the water clear. Floating species are those that are not anchored at all in the pond. Examples of floating species include duckweed, water lettuce, and water hyacinth. These plants also help keep the water clear by limiting the amount of sunlight that the algae receive and need to grow. A mini-wetland in a backyard can provide many of the benefits that natural wetlands offer. A mini-wetland can also replace the natural function of the land that was in place before the ground was developed and houses built.

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Backyard wetlands are advantageous because they temporarily store, filter, and clean runoff water from houses and lawns. They also provide habitat for many forms of life, such as toads, frogs, salamanders, butterflies, bees, and birds. Fortunately, many wetland plants do not require standing water in order to grow. Wetlands can be naturally built into a low or continually wet spot in the yard, or an area can be converted into one. A wetland is just an area where water covers the soil or keeps it saturated for at least two to three weeks during the growing season. Wetlands can be placed anywhere that water accumulates faster than it drains away. Wetlands grow grasses, cattails, and other marshy vegetation. The amount of time the soil is kept wet will determine which plants a wetland will support.

Backyard Mulching Mulching is one of the simplest and most beneficial of practices used in a garden. Mulch is simply a protective layer of a material that is spread on top of the soil. Mulches can be organic, such as grass clippings, straw, or bark chips; or they can consist of inorganic materials, such as stones, brick chips, and plastic. According to the Department of Agriculture, mulching is beneficial in backyard gardens because it does the following: • • • • •

Protects the soil from erosion. Reduces soil compaction from heavy rains. Prevents weed growth. Helps conserve soil moisture so the garden doesn’t have to be watered as often. Helps soil maintain a more even soil temperature.

Organic mulch improves the condition of the soil. When mulch decomposes in the soil, it provides the organic matter that helps keep the soil structure loose and aerated, not compacted. Because of this, plant roots grow better and water infiltrates the soil better, allowing


the soil to hold more water. It is also a source of plant nutrients and provides a healthy environment for earthworms and other beneficial soil organisms.

Backyard Nutrient Management There are many nutrients required by plants, even in backyard gardens. Nitrogen, phosphorus, and potassium are required in the largest amounts. Nitrogen is responsible for lush vegetation; phosphorus for the flowering and fruiting of plants; and potassium to improve resistance to disease. In addition, calcium, magnesium, and sulfur are also very important. These six nutrients are referred to as macronutrients. Soil also needs micronutrients—important nutrients required in only small amounts. These nutrients include zinc, iron, copper, and boron. The level of nutrients can be a delicate balancing act. While it’s important for the soil to have them, they can be detrimental if they exist in quantities that are too large. Not only can they harm plant growth, but they can infiltrate and pollute groundwater or surface waters. One way to manage nutrients in a backyard conservation environment is to use a soil testing kit. This allows the testing and determination of concentrations of nutrients and soil pH levels so that the correct level of nutrients can be added. In this way, the right amount of nutrients can be added so that excess nutrients won’t pollute clean lakes or streams. Backyard Pest Management Backyard gardens often have pest problems. Yard pests include weeds, insects, and disease-causing organisms such as fungi, bacteria, and viruses. Insects can damage plants in many ways. They can chew plant leaves and flowers. Some can suck out plant juices (such as aphids, mealy bugs, and mites); others cause damage by burrowing into stems, fruits, and leaves. Planting resistant varieties of plants can prevent many pest problems, such as disease. Rotating annual crops in a garden also prevents

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some diseases. Plants that have the correct amount of nutrients available in the soil are also more resistant to disease, because they are in a healthier environment. Mulching is a very effective technique against the spread of weeds. Backyard conservation methods can include some form of integrated pest management (IPM). IPM relies on several techniques to manage pests without the excessive use of chemical controls. IPM can include monitoring plants, determining tolerable injury levels, and applying appropriate pest management. IPM doesn’t treat the entire area with a chemical—it looks at specific areas that need control and applies treatments in the affected areas only, in the correct amounts, and at the correct time. Spot spraying is an example of this type of management. It is cost effective and limits damage to nontargeted species. Management practices for weeds include hoeing, pulling, and mulching. Weeding is most important when plants are small. Wellestablished plants can often tolerate competition from weeds. Disease management generally involves the removal of the diseased plants. Diseased branches on trees can be pruned. Additives to soil are also available to reduce damage from some insects. Biological controls are also useful. Some insects are predators of pests and can help keep their populations under control. Rotating crops to reduce disease and insect infestations also accomplishes pest management, as well as do growing tall grass hedges in order to provide habitat for beneficial insects.

Backyard Terracing Terraces are used in backyards that consist of steep slopes. Terraces can create several backyard mini-gardens to grow flowers and vegetables. Terraces prevent erosion by breaking up a long slope into a series of level steps. This enables heavy rains to soak into the soil rather than run off and contribute to soil erosion. Backyard Tree Planting When trees are planted in the backyard, they can provide valuable habitat for many types of wildlife. Trees can also help reduce home


heating and cooling costs, help clean the air, and provide shelter from the wind.

Backyard Water Conservation Wise use of water for gardens and lawns helps protect the environment and provides for optimum growing conditions. There are many practices available to promote backyard water conservation. Growing xeriphytic species (plants that can survive in dry conditions) is one way. Plants that use low amounts of water include yucca, California poppy, blanket flower, moss rose, juniper, sage, cactus, thyme, crocus, and even primrose. Other ways to conserve water include using mulches and installing windbreaks to slow winds and help reduce evapotranspiration. Watering in the early morning is also a beneficial conservation practice. If watering is done before the sun is intense enough to cause evaporation, more water will be utilized directly for the plants. Another method some gardeners use is drip, or trickle irrigation—plastic tubing that supplies a slow, steady source of water from sprinkler heads suspended above the ground. Native plants (plants that grow naturally in the area) are also important because they naturally use less water than nonnative species. Native species have evolved under local conditions and usually have well-developed mechanisms for surviving extremes in the weather. Wildlife Habitat Habitat is a combination of food, water, shelter, and space that meets the needs of a species of wildlife. Even a small yard can be landscaped to attract birds, butterflies, small animals, and insects. Trees, shrubs, and other plants provide shelter and food for wildlife. Nesting boxes, feeders, and watering sites can be added to improve the habitat. Wildlife habitat covers the horizontal dimension (the size of the yard) as well as a vertical dimension from the ground to the treetops. Different wildlife species live in the different vertical zones, enabling several habitats to exist in a backyard setting. Trees and shrubs are also

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Backyard conservation activities, such as hanging a hummingbird feeder, are great ways for individuals to help conserve the natural environment. (Nature’s Images)


important sources of food for wildlife. Birdhouses and shelters are easy to add to a backyard habitat to increase the wildlife that visits the area. Plant species that birds enjoy for food or nesting can be grown to encourage wildlife visits. Clean, fresh water is also critical in a backyard habitat. Birds, bats, butterflies, and other wildlife need water. Water can be stored in a saucer, birdbath, or backyard pond. With a little time, creativity, and determination, anyone can promote backyard conservation.

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9

Conclusion: Future Issues and Sustainable Resources

T

oday is a time of rapid growth in the human population along with incredible advances in technology. With both of these, however, come changes to the land. But are these changes good or bad? Today, not all scientists and conservationists agree with each other. Some believe that although populations are growing and more demand is being put on the land, that future advances in technology will counteract any negative impact. Other specialists believe that the impacts of growing societies will irreversibly damage the health of the land. The goal of this chapter is to look at these timely issues, the implications of the greenhouse effect, habitat destruction and loss, and the future of the land and its ability to support animal life. It then outlines the importance of recycling, reducing, and reusing resources, and what simple actions everyone can take to help minimize future impacts on the land. The chapter then examines projected trends for the next three decades, the role of seed banks, and finally, long-term stewardship and how everyone can live smarter and more responsibly. 186

Conclusion: future issues and sustainable resources

What the Future May Hold Some scientists predict that by the twenty-second century, there could be twice as many people living on the Earth as there are now. The implications of this raise several important questions—where will everyone live? What will everyone eat? Are there enough resources on the land to support more people, and will the land be fertile enough to grow food for everyone? What about energy needs? Are there enough coal, oil, gas, and other energy resources still contained in the land to supply this power? How much air pollution will there be? How will that affect the land? What about the greenhouse effect? What will happen to the hundreds of plant and animal species that live on the land now and are currently endangered? Will humans’ impact on the land cause them to become extinct? Have people learned enough from past experiences—like the Dust Bowl of the 1930s—to know how to maintain the health of the land? These are all questions that scientists, conservationists, and land managers have to consider now—they cannot wait for the future to give these issues attention. Just like high-school students need to start thinking and planning for their futures (college, careers, and families), these professionals also need to plan now for the future, because the future depends on decisions that are being made today. Because the conservation of natural resources affects the entire world, these plans and policies need to be applied on a global scale in order to make a lasting difference for the future. Many countries around the world are becoming more environmentally conscious about reducing waste, recycling, controlling pollution, and focusing more on the benefits of renewable resources. Today, many organizations are trying to promote international cooperation on the conservation of natural resources. For example, organizations, such as the World Conservation Union and World Wildlife Fund, promote resource conservation in the international arena. Another example of international cooperation is the Kyoto Protocol of 1997, backed by the United Nations, which is geared at reducing greenhouse gas emissions in order to control global warming. The Protocol is currently backed and supported by more than 160 countries globally.

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Today is the time to make these plans and begin working toward their goals—especially in the areas that demand serious and rapid attention, such as the destruction of the rain forests, which contain the Earth’s richest wildlife habitats. Every day, chunks of rain forest are lost to miners, ranchers, and loggers. Many professionals estimate that at the current rate of rain forest destruction, all rain forests may be gone in the next 50 years. Rapid modernization of developing countries may also have a significant affect on the land, such as that happening in China and India. For example, there is currently such a demand for materials to produce concrete that it has impacted construction progress in the United States—making supplies scarce. Although nature has proved its resiliency over eons of geologic time, some of the changes and demands put on the land have never happened before. Modern technology and the lifestyles of convenience that many people enjoy have not severely impacted the Earth until now, which is why having good management plans in place is a challenge that must be dealt with now.

The Greenhouse Effect The greenhouse effect is a major problem affecting the land and atmosphere. One of the biggest contributors to greenhouse gases are the emissions resulting from the burning of fossil fuels. Another greenhouse gas—methane—comes from landfills, coal mines, oil and gas operations, and agriculture. The chemical compounds in the Earth’s atmosphere that act as greenhouse gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is reflected back toward space as heat. Greenhouse gases, however, absorb radiation and trap the heat in the atmosphere. As more countries become developed and industrialized, more greenhouse gases are released into the atmosphere. This rising level of gases is of concern to scientists. They believe the effects of rising temperatures may produce changes in weather, sea levels, and land use patterns. This, in turn, leads to climate change.


World carbon dioxide emissions are expected to increase by 1.9% each year between now and 2025. Developing countries’ emissions are expected to grow above the world average at 2.7% annually between now and 2025 and surpass the emissions of industrialized countries near the year 2018. In order to control the rising problem of the greenhouse effect, it is important that renewable energy resources on the land continue to be developed and used in order to offset the burning of fossil fuels. Using renewable, sustainable energy will continue to become more and more critical in the struggle to protect the fragile balance of ecosystems in the future.

Habitat Destruction and Loss A habitat is a place with a particular environment where both plants and animals live, and many habitats are being destroyed by land use changes. For example, panda habitat is being destroyed at an alarming rate, leaving the pandas without a food source as the bamboo forests are cut down. This is an example of the delicate interrelationships that exist between the land, plant, and animal components in a habitat. Often, animals will adapt and evolve to remain compatible with, and remain in, the ecosystem. They adapt to be able to survive on the food that exists there. Plants also evolve in habitats in order to be compatible with the animal life. For example, some flowers give off a unique scent that will attract a specific insect, which will pollinate the flowers. The bright colors of some berries attract birds to feed on them. Whole communities of plants are being destroyed every day on land all over the world, especially in the tropical regions. Rain forest habitats are being destroyed at an alarming rate in order to cultivate timber or clear the land for grazing. Firewood is often in high demand for cooking and heating in many areas, which adds to the already growing problem. Because most of the nutrients in a rain forest are contained in the biomass above ground (living matter, such as plants), the soils themselves aren’t highly fertile. Clearing rain forest land often

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destroys it and keeps anything from growing and producing. Because the large trees take so long to grow, species are becoming endangered. If the plants are removed from the habitat, this adversely affects the animal life that depends on the plants for food, shelter, and survival. Good management practices attempt to take all the resources in the habitat and find a healthy balance to meet many diverse needs. Land managers must look at the ecosystem on a broad scale, taking into account plant life, animal life, water quality, soil composition, air quality, different uses of the land, and human impact. Responsible management for the twenty-first century includes employing practices that use the land to meet both present needs, as well as protect its long-term quality. If one component in the system— however small—is damaged, it can impact and hurt the entire system. That is why land managers monitor the health of plants and animals.

Facts About Endangered Species • According to scientists, more than 1.5 million species have been identified on the Earth today. Recent estimates state that at least 20 times that many species inhabit the planet. Scientists have many more to find. • In the United States, 735 species of plants and 496 species of animals are listed as threatened or endangered. • Of these listed species, 266 have recovery plans currently under development. • There are more than 1,000 animal species endangered worldwide. • There are more than 3,500 protected areas in existence worldwide. These areas include parks, wildlife refuges, and other reserves. They cover a total of nearly 2 million square miles (5 million sq. km), or 3% of the total land area. Sources: U.S. Fish and Wildlife Service and National Wildlife Federation


If one of the components of the ecosystem is threatened, it is a warning of a possible domino effect. Wise management practices keep this from happening.

The Future of Land Animals When the pace of change is slow in an ecosystem, species can often adapt in order to survive. Those that cannot adapt become extinct. There have always been new species evolving to take their place. Today, however, extinction is happening more rapidly than the birth of new species. Unfortunately, humans are largely to blame. The world’s rapidly growing population consumes more and more resources. As forests are cut down, land is cultivated, and areas are mined for minerals, habitat is taken from animals, causing species to become threatened, endangered, and even extinct. If this trend continues, it is not difficult to see where it will lead. Wildlife all over the world is struggling to survive—in countries far away such as Africa, Asia, or Russia as well as in our own backyards—in order to keep hold of its natural habitat. All animal species require wild areas in order to thrive. It is important for us to save as much space for wildlife as we can. Humans need to remember that their actions today may affect the future survival of animals that are not yet endangered. It takes communities—even countries—working together to ensure the future of animals. The Importance of Recycling, Reducing, and Reusing Having to produce new materials from the land’s resources takes a lot of energy and also causes impact in some way to the land the resource is removed from. The land can stay much healthier if people recycle, reduce, and reuse products. Every American throws away about 1,000 pounds (454 kg) of trash a year. The most effective way for consumers to help reduce the amount of energy consumed by industry is to decrease the number of unnecessary products produced and to reuse items wherever possible. Purchasing only those items that are necessary

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and reusing and recycling products can also reduce energy use in the industrial sector. Everyone can take an active role in reducing, reusing, and recycling materials. In order to reduce consumption, each person should buy only the products that they need. Purchasing fewer goods means less waste to throw away. This practice also results in fewer goods being produced and less energy being used in the manufacturing process. Buying goods with less packaging also reduces the amount of waste generated and the amount of energy used. Products should be bought that can be used repeatedly. If items are bought that can be reused, rather than disposable items that are used once and thrown away, it will save natural resources. It will also save the energy used to make them and reduce the amount of landfill space needed to contain the waste. Recycling should be a priority. Using recycled material almost always consumes less energy than using new materials. Recycling reduces energy needs for mining, refining, and many other manufacturing processes. Recycling a pound of steel saves enough energy to light a 60-watt light bulb for 26 hours. Recycling a ton of glass saves the equivalent of 9 gallons (34 L) of fuel oil. Recycling aluminum cans saves 95% of the energy required to produce aluminum from bauxite. Recycling paper cuts energy usage in half. Efficiency and conservation are key components of sustainability—the concept that every generation should meet its needs without compromising the needs of future generations. Sustainability focuses on long-term strategies and policies that ensure adequate resources to meet today’s needs, as well as tomorrow’s. In terms of energy needs, sustainability also includes investing in the research and development of advanced technologies for producing conventional energy sources, promoting the use of alternative energy sources, and encouraging sound environmental policies. Every person can take an active role to help reduce waste at home by learning basic waste-saving habits, for example, by buying products that use minimal packaging or that come in concentrated forms.


According to the U.S. Environmental Protection Agency, most products can be reused, repaired, recycled, or composted instead of being simply thrown away. For example, everyone can do the following: 1. Reduce • Buy the largest size package and products that do more than one thing—for example, shampoos that include conditioners. • Buy concentrated products or compact packages, such as frozen juices and fabric softeners that can be mixed with water at home. • Look for products with minimal packaging. This uses fewer natural resources, and there is less to throw away. • When mowing the lawn, leave grass clippings on the ground instead of bagging them. Grass clippings decompose quickly, adding nutrients to the soil. 2. Reuse • Buy reusable products such as rechargeable batteries. • Pass on magazines, catalogs, and books to neighbors, hospitals, schools, and nursing homes. • Reuse plastic or glass containers for food storage, to store items such as nails, and so on. • Reuse plastic shopping bags, boxes, and lumber. • Reuse wrapping paper, gift bags, and bows. Use the Sunday comics for wrapping children’s birthday presents. 3. Repair • Try to repair before considering replacing lawn mowers, tools, vacuum cleaners, and TVs. • Donate items that cannot be repaired at home to local charities or vocational schools (someone there may be able to repair and use them). • Keep appliances in good working order. Properly maintained appliances are less likely to wear out or break and will not have to be replaced as frequently.

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4. Recycle • Shop for items that are recyclable or are made from recycled materials. • Recycle newspapers, plastics, glass, and cans. • If a recycling program does not exist in your community, contact community officials to see if it would make sense to start one. 5. Compost • Compost yard and kitchen waste. Compost makes an excellent fertilizer and improves the soil. • If there is no room for a compost pile, offer compostable materials to community composting programs or garden projects nearby. If every person took part in a conservation effort, large quantities of land resources could be protected and saved for future generations. Many people working together with a common goal is what is necessary in order to make a lasting difference.

Synthetic Materials The use and development of synthetic materials is another way to conserve resources on land. One current development in the creation of alternative land resources to better protect the land, control air pollution, and address the greenhouse effect is the use of biomass. Biomass is a mixture of farming wastes, grasses, trees, bark, sawdust, and other living matter that is converted into energy by burning it, changing it to a gas, or converting it to a liquid fuel. A primary goal of the National Energy Policy is to increase energy supplies by using a more diverse mix of existing resources available in the country and to reduce the dependence on imported oil. The U.S. Department of Energy Biomass Program develops technology for conversion of biomass to valuable fuels, chemicals, paper, materials, and power in order to reduce the United States’ dependence on foreign oil,


cut back on polluting emissions, and to encourage the growth of biorefineries, which provide jobs for many people. Biomass is one of the United States’ most important resources. It has been the largest U.S. renewable energy source since 2000. It also provides the only renewable alternative for liquid transportation fuel. Today’s biomass uses include ethanol, biodiesel, biomass power, and industrial process energy. In the future, biorefineries will use advanced technology such as the hydrolysis of cellulosic biomass to sugars and lignin, and thermochemical conversion of biomass to synthesis gas for fermentation and catalysis of these platform chemicals to produce biopolymers and fuels. In order to expand the role of biomass in America’s future, the Department of Energy’s Biomass Program helps biomass technologies to advance with extensive and ongoing research and development. As a domestic, renewable energy resource, biomass offers an alternative to conventional energy sources and provides national security, economic growth, and environmental benefits. It especially benefits the land if new oil and gas wells do not have to be tapped. Agriculture and forestry residues—especially those from paper mills—are the most common biomass resources for generating electricity, industrial process heat, and steam for a variety of bio-based products. Current biomass consumption in the United States is dominated by industry—most of that energy is generated from wood. However, use of liquid transportation fuels such as ethanol and biodiesel, currently derived from agricultural crops, is increasing dramatically. Ethanol and biodiesel, made from plants instead of petroleum, can be blended with or substituted for gasoline and diesel. Using biofuels is good energy management because biofuels reduce toxic air emissions, greenhouse gas buildup, and dependence on imported oil, while supporting agriculture and America’s rural communities. Unlike gasoline and diesel, biofuels contain oxygen. This means that adding biofuels to petroleum products allows the fuel to combust more completely, which reduces air pollution. As biomass

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energy gains momentum, “dedicated” energy crops may be grown— such as fast-growing trees and grasses—to supply the biomass.

The Next 30 Years The United Nation’s Environment Programme (UNEP), as a result of conducting global environmental assessments, has expressed concern that many of the Earth’s ecosystems have already been, and continue to be, impacted to the point of collapse. UNEP attributes much of this impact to the result of massive worldwide overdevelopment, poorly planned development, overuse of freshwater resources, and worldwide pollution from human populations now and into the near future. They believe that despite positive action that has been taken by North America and Europe to clean up the environment and the international effort to reduce the production and consumption of ozone-destroying chlorofluorocarbons (CFCs), declining world environmental quality and global warming threatens to overwhelm those local successes. Another finding in their studies is that nearly 15% of the Earth’s farmland has now been severely degraded through overgrazing, overlogging, overfarming, and chemical contamination. They have also determined that 50% of the world’s rivers are now seriously depleted or polluted. In addition, dams have fragmented 60% of the world’s largest 227 rivers and other engineered structures, which has in turn destroyed wetlands and other ecosystems that people depend on. Whatever the findings of investigations like these, one thing is clear: conservation of the land’s precious resources is critical now—and in the future—if societies expect to maintain the standards of living they enjoy today. As more people become conservation minded, these trends will be able to reverse direction and enable society to create sustainable land use and promote effective land stewardship. Seed Banks One direction scientists are looking to in order to ensure productivity of the land in the future for producing food for people worldwide is through the development of seed banks. Because many plants have


the promise of new applications and uses—such as sources of new medicines, new energy sources, new foods, and new environmental benefits—scientists keep a supply of seeds secure in seed banks. Seed banks are used to store wild plants, cultivated plants, and scientifically developed plant varieties. The seeds can either be frozen in liquid nitrogen or stored in airtight containers. Seed banks store seeds for rare plants, and threatened and endangered plants for preservation. According to the U.S. Department of Agriculture, seeds are also stored for future research. Only a small percentage of the world’s plants have been tested for their potential medicinal values. Storing the seeds allows scientists to be able to study the plants in the future with new technology as it is developed. For example, in a cryopreservation process, a container of seeds is lowered into a vat of liquid nitrogen that freezes them. The vats can hold 5,000 containers of as many as 2,000 seeds each. Seeds stored in this manner can be preserved and still germinate after thousands of years, but scientists do occasionally remove samples in order to check them to make sure they are still in good condition.

Creating Sustainable Land Systems— Long-term Stewardship of the Land and Living Smarter As illustrated throughout this book, there are many critical facets involved in creating successful land use and maintaining land resources. From practical experience, land managers have gained the knowledge of how to properly care for the land. With conservation in mind, they have been able to contribute significantly to land stewardship. As population increases and urban areas continue to encroach upon rural areas, a struggle sometimes occurs to maintain a healthy, wellbalanced environment—and that is everyone’s responsibility. Everyone is somebody’s neighbor, and everyone’s actions have the potential to hurt or help the land. We can practice responsible conservation techniques in our own backyards. We can do our part to promote water quality and biodiversity. Our responsible land management practices can benefit the environment by controlling erosion and the fertility of

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Elbert Wells, an NRCS Project Leader, and students from the Hartranft Elementary School in Philadelphia, collect seed heads from marigolds. The students plant, maintain, and harvest flowers and vegetables in a garden they built themselves. (Photo by Bob Nichols, NRCS)

the soil. Our willingness to recycle, reduce, and reuse will help protect the environment now and for generations to come. In order to conserve our resources and promote land stewardship, we must realize it is a long-term commitment. Actions we take now can affect the environment for others long into the future. Everyone has a role in maintaining healthy ecosystems and keeping the land productive.

Appendix Geologic Time Scale Geologic period

Approximate years

Climate

Precambrian

4,600–570 million Wet years ago

First one-celled and multi-celled organisms

Cambrian

570–505 million Wet years ago

First shells, trilobites dominant

Ordovician

505–438 million years ago

First fish

Silurian

438–408 million Swampy years ago

First land plant fossils

Devonian


First amphibians

Carboniferous

362–290 million Swampy Giant horsetails, ferns, club years ago mosses, large primitive trees, giant amphibians, and dragonflies

Permian

290–245 million Cooler years ago

Conifers, gingkoes, and other primitive plants

Triassic

245–208 million Drier years ago

Cycads and meat-eating dinosaurs

Jurassic


Cretaceous

145–65 million Drier Horned dinosaurs, snakes, years ago and flowering plants, bulrushes and willow trees

Tertiary

65–2 million Drier Earliest large mammals; years ago extinction of dinosaurs (at the Cretaceous-Tertiary boundary 65 million years ago)

Quaternary


Wet

Swampy

Predominant life-forms

Cooler and Swamp cypress, ferns, longneck wetter dinosaurs, and flying reptiles

Drier

199

Appearance of humans

200

Appendix

National Parks of the United States New England: Acadia, Maine Mid-Atlantic: Shenandoah, Virginia South: Hot Springs, Arkansas Mammoth Cave, Kentucky Great Smoky Mountains, North Carolina and Tennessee Southeast: Biscayne, Florida Dry Tortugas, Florida Everglades, Florida Caribbean: Virgin Islands Great Lakes: Isle Royale, Michigan Midwest: Voyageurs, Minnesota Theodore Roosevelt, North Dakota Badlands, South Dakota Wind Cave, South Dakota Southwest: Grand Canyon, Arizona Petrified Forest, Arizona Saguaro, Arizona Carlsbad Caverns, New Mexico Big Bend, Texas Guadalupe Mountains, Texas Rocky Mountains: Mesa Verde, Colorado Rocky Mountain, Colorado Yellowstone, Idaho, Montana, and Wyoming

Glacier, Montana Death Valley, Nevada Great Basin, Nevada Arches, Utah Bryce Canyon, Utah Canyonlands, Utah Capitol Reef, Utah Zion, Utah Grand Teton, Wyoming

West Coast: Channel Islands, California Death Valley, California Joshua Tree, California Kings Canyon, California Lassen Volcanic, California Redwood, California Sequoia, California Yosemite, California Crater Lake, Oregon Mount Rainier, Washington North Cascades, Washington Olympic, Washington Arctic: Denali, Alaska Gates of the Arctic, Alaska Glacier Bay, Alaska Katmai, Alaska Kenai Fjords, Alaska Kobuk Valley, Alaska Lake Clark, Alaska Wrangell St. Elias, Alaska Pacific Islands: Haleakala, Hawaii Hawaii Volcanoes, Hawaii

Glossary absolute age The approximate age of a geologic event, feature, fossil,

or rock in years; “absolute” ages are determined by using natural radioactive “clocks”; the preferred term is radiometric age. accretion A process that adds part of one tectonic plate to a larger

plate along a convergent (collisional) plate boundary. acid rain Rain that is made abnormally acidic by gases released from

the burning of fuels like coal; the gases dissolve in the water in the air and fall as acid rain, snow, or mist. active fault A fault that is likely to have another earthquake some-

time in the future; faults are commonly considered to be active if they have moved one or more times in the last 10,000 years. active volcano A volcano that has erupted within historical time and

is likely to do so again in the future. adaptation A structure or behavior that helps an organism survive in

its environment. aftershocks Earthquakes that follow the largest shock of an earth-

quake sequence; they are smaller than the main shock and within 1–2 fault lengths distance from the main shock fault; aftershocks can continue over a period of weeks, months, or years; in general, the larger the main shock, the larger and more numerous the aftershocks, and the longer they will continue. air pressure A force exerted by air in the atmosphere as it weighs

down on Earth. Air pressure decreases with increasing altitude. alluvium Sand, gravel, and silt deposited by rivers and streams in a

valley bottom. alpine tundra A treeless zone similar to Arctic tundra, but found

above the timberline on mountains. annual A plant that completes its life cycle in a single year. aquatic An animal or plant that lives in water. aquifer A body of rock that is sufficiently permeable to conduct

groundwater and to yield economically significant quantities of water to wells and springs. 201

202

Glossary

archaeologist A scientist who studies buried remains to investigate

how people lived in the past. archaeology The science that focuses on the study of past human

cultures. argillic horizon A clay-rich layer of soil; clay often forms in overlying

soil layers from the decomposition of feldspars and other minerals; the extremely fine clay particles are gradually carried down by water to accumulate into the argillic horizon. argillite The name used for unusually hard, fine-grained sedimen-

tary rocks, such as shale, mudstone, siltstone, and claystone; commonly black. asthenosphere The uppermost layer of the mantle, located below the

lithosphere; this zone of soft, easily deformed rock exists at depths of 62–435 miles (100–700 km). atmosphere The mixture of gases, aerosols, solid particles, and water

vapor that envelops the Earth. avalanche Masses of rock, snow, or ice that fall or slide suddenly

under the force of gravity. bacteria Extremely small living things that bring about the decay of

plant and animal remains and wastes. bedrock Relatively hard, solid rock that commonly underlies softer

rock, sediment, or soil. biodiversity A wide range of life living within a specific ecosystem;

healthy areas have high biodiversity. biogeography The science that deals with the geographical distribu-

tion of animals and plants. biomass The total mass of all living organisms or of a particular set

of organisms in an ecosystem. biome A major area of the world with its special kind of climate,

plants, and animals. biosphere The realm of all living things.

Glossary 203

biostratigraphy The branch of geology concerned with the separa-

tion and differentiation of rock units by means of the study of the fossils they contain. bog A wet, spongy marsh area. botanist A person trained in the study of plant life. botany The branch of biology dealing with plant life. carbon dioxide A colorless gas that makes up 0.03% of the atmo-

sphere; it is released through the respiration of living things. carnivore An animal or plant that feeds on flesh. chlorofluorocarbons Also called greenhouse gases or CFCs, they

are a group of gaseous compounds that contain carbon, chlorine, fluorine, and sometimes hydrogen and are used as refrigerants, cleaning solvents, aerosol propellants, and in the manufacture of plastic foams; they are suspected of being a major cause of stratospheric ozone depletion as well as of absorbing long-wave electromagnetic radiation. cloud forest A lush, misty forest found on mountains in the tropics. community A population of plants and animals that live together

and affect each other. coniferous tree A tree that bears seeds in cones made of overlapping

scales; coniferous trees, which are gymnosperms, include pines, spruces, and firs. contour lines Parallel lines used on topographic maps to show

the shape and elevation of the land; they connect points of equal elevation. core The innermost part of the Earth; the outer core extends from

2,500–3,500 miles (4,023–5,632 km) below the Earth’s surface and is liquid metal; the inner core is the central 500 miles (805 km) and is solid metal. creep Slow, more or less continuous movement occurring on faults

due to ongoing tectonic deformation; faults that are creeping do not tend to have large earthquakes.

204

Glossary

crust The Earth’s outermost layer. deciduous trees Trees that shed their leaves each year at the end of

the growing season. deforestation The clearing of forest, usually carried out by cutting

down or burning trees. dendrochronology The technique of finding a tree’s age by counting

the rings in its trunk. deserts Those regions where there is little rainfall and where few

plants and animals live. dominant Most important; the plant or animal species that

largely determines what other species share its habitat is said to be dominant. dormant period A time during which a plant rests and makes little or

no new growth. dormant volcano An active volcano that is in repose (quiescence) but

is expected to erupt in the future. drumlin A low, smoothly rounded, elongate hill of compact glacial

till built under the margin of the ice and shaped by its flow, or carved out of an older moraine by readvancing ice; its longer axis is parallel to the direction of movement of the ice; it usually has a blunt nose pointing in the direction from which the ice approached and a gentler slope tapering in the other direction. dune A low hill of drifted sand in coastal areas that can be bare or

covered with vegetation. earthquake This term is used to describe both sudden slip on a

fault and the resulting ground shaking and radiated seismic energy caused by the slip, or caused by volcanic or magmatic activity, or other sudden stress changes in the Earth. earthquake hazard Anything associated with an earthquake that may

affect the normal activities of people; this includes surface faulting, ground shaking, landslides, liquefaction, tectonic deformation, and tsunamis.

Glossary 205

ecology The study of how living things affect, and are affected by,

their environment. ecosystem A part of ecology consisting of the environment, its living

parts, and the nonliving factors that affect it. endangered Close to extinction. endangered species Any animal or plant species in danger of extinc-

tion throughout all or a significant portion of its range. environment The world around us, or our surroundings, including

all living things; the place where an animal or plant lives may be called its environment. eolian Pertaining to the wind; especially said of such deposits as

loess (a loamy deposit) and dune sand, of sedimentary structures such as wind-formed ripple marks, or of erosion and deposition accomplished by the wind. equator An imaginary line around Earth, midway between the

North and South Poles. erosion The gradual wearing away of land by the action of wind,

rain, rivers, ice, or the sea. esker A serpentine ridge of roughly stratified gravel and sand that

was deposited by a stream flowing in or beneath the ice of a stagnant or retreating glacier and was left behind when the ice melted. estuary An environment where terrestrial, freshwater, and seawater

(saline) habitats overlap. evaporation The change of a liquid into a vapor. evergreen A plant that is green year-round and that does not lose all

its leaves in winter, such as a pine tree. evolve The changes in a species over long periods giving rise to a

new species. extinct No longer in existence. fault A fracture along which the blocks of crust on either side have

moved relative to one another parallel to the fracture; strike-slip faults are vertical (or nearly vertical) fractures where the blocks

206

Glossary

have mostly moved horizontally; if the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral; dip-slip faults are inclined fractures where the blocks have mostly shifted vertically; if the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed reverse (or thrust); obliqueslip faults have significant components of both slip styles. food chain A chain of living things through which energy is passed

as food. food web A complex network of interactions between plants and

animals. Food webs involve many interconnecting food chains. fossil The preserved record of an organism that lived long ago. fossil fuels Those fuels (oil, gas, and coal) that have been formed

in the ground over millions of years from the decay of once living things. geodesy The science of determining the size and shape of the Earth

and the precise location of points on its surface. geographic information system (GIS) A combination of computer

hardware and software that allows storage and manipulation of information suitable for mapping; a GIS software system synthesizes geographic position data and other data in order to create a map; data on processes can be incorporated to make a geographic model. geologic time The period of time extending from the formation of

the Earth to the present. geology The study of the planet Earth, including the materials it

is made of, the processes that act on those materials, the products formed, and the history of the planet and its life-forms since its origin. geomorphology The study of the character and origin of landforms,

such as mountains and valleys.

Glossary 207

geospatial data Information pertaining to a place linked to coordi-

nates or other positional information. geosphere The nonliving parts of the Earth, the lithosphere, the

atmosphere, the cryosphere, and the hydrosphere. geyser A jet of hot water or steam produced by volcanic activity. glacier A thick mass of ice resulting from compacted snow that

forms when more snow accumulates than melts annually. global warming The process by which Earth is getting warmer

because of changes in the atmosphere caused by human actions. gravity A force that pulls objects toward Earth. greenhouse effect The warming of the surface and lower atmosphere

of the Earth, which is compounded by gases in the atmosphere, such as the carbon dioxide emitted from burning fossil fuels. groundwater The supply of freshwater found beneath the surface

of the Earth (usually in an aquifer) that often supplies wells and springs. habitat A place with a particular environment where plants and

animals live. hemisphere One-half of the Earth; the Northern Hemisphere is the

half to the north of the equator; the Southern Hemisphere is the half to the south of the equator. herbivores Animals that eat plants. hot spot An area in the middle of a lithospheric plate where magma

rises from the mantle and erupts at the Earth’s surface; volcanoes sometimes occur above a hot spot, such as the Hawaiian Islands. hydrogeology The science that deals with subsurface waters and geo-

logic aspects of surface water. hydrological cycle The movement of water from the sea through the

air to the land and back to the sea. hydrosphere The water that covers 71% of the Earth’s surface as

ocean, lakes, rivers, and streams; the hydrosphere also includes

208

Glossary

groundwater, water that circulates below the Earth’s surface in the upper part of the lithosphere. ice age A period in history when Earth’s climate was cooler and the

polar ice caps expanded; the last ice age ended 10,000 years ago. irrigation The use of artificially channeled water to grow crops. landmark Any prominent object on land that can be used in deter-

mining a location or direction. landslide The downslope movement of soil and/or rock. latitude Angular distance measured in degrees, minutes, and sec-

onds north and south to the geographic poles from the equator. lava The term used for magma once it has erupted onto the

Earth’s surface. leeward The side of a landmass sheltered from the wind; the oppo-

site of windward. limestone A type of rock formed over thousands of years from the

shells of tiny sea creatures building up on the seabed; chalk is a type of limestone. liquefaction A process by which water-saturated sediment temporar-

ily loses strength and acts as a fluid; earthquake shaking can cause this effect. lithology The description of rock composition (what it is made of)

and texture. lithosphere The outer, solid part of the Earth, including the crust

and uppermost mantle; the lithosphere is about 62 miles (100 km) thick, although its thickness is age dependent (older lithosphere is thicker); the lithosphere below the crust is brittle enough at some locations to produce earthquakes by faulting, such as within a subducted oceanic plate. It is divided into a mosaic of 16 major slabs, or plates. lithospheric plates A series of rigid slabs (16 major ones at present) that

make up the Earth’s outer shell; these plates float on top of a softer, more plastic layer in the Earth’s mantle (also called tectonic plates).

Glossary 209

longitude Angular distance measured in degrees, minutes, and sec-

onds 180 degrees east and west from the prime meridian, the imaginary north–south line through Greenwich, England. magma Molten rock containing liquids, crystals, and dissolved gases

that forms within the upper part of the Earth’s mantle and crust; when erupted onto the Earth’s surface, it is called lava. mantle A zone in the Earth’s interior between the crust and the core

that is 1,740 miles (2,900 km) thick; the lithosphere is composed of the topmost 39–42 miles (65–70 km) of the mantle and the crust. metabolism The chemical processes in cells that are essential to life. micropyle The tiny hole in the ovule through which the pollen tube

enters during fertilization. minerals Any of certain elements, such as iron, that are needed by

plants and animals. molecule The smallest particle of a substance that retains all the

properties of a substance. monsoon A very rainy season in Southeast Asia, or the wind that

causes the rainy season. moraine A mound or ridge of unstratified glacial drift, chiefly till,

deposited by direct action of glacier ice. mudflow A flowing mixture of water and debris (intermediate

between a volcanic avalanche and a water flood) that forms on the slopes of a volcano; sometimes called a debris flow or lahar, a term from Indonesia where volcanic mudflows are a major hazard. multiple use A combination of balanced and diverse resource uses

that takes into account the long-term needs of future generations for renewable and nonrenewable resources, including, but not limited to, recreation, range, timber, minerals, watershed, and wildlife and fish, along with natural scenic, scientific, and historical values. niche The position that an animal or plant holds in the community. nutrients Substances that plants and animals need in order to grow. organism Any living thing, including plants or animals.

210

Glossary

oxygen The gas that makes up nearly 21% of the air; it is essential

for life. perennial A plant that grows for more than two years. permafrost Permanently frozen ground at high latitude and

high elevation. photosynthesis The manufacture of food, mainly sugar, from carbon

dioxide and water in the presence of chlorophyll, using solar energy and releasing oxygen. plate tectonics A theory supported by a wide range of evidence that

considers the Earth’s crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. plateau An area of relatively flat land higher than its surroundings. playa A term used in the southwestern United States for a dry, bar-

ren area in the lowest part of an undrained desert basin, underlain by clay, silt, or sand, and commonly by soluble salts. prevailing winds The direction from which winds most frequently

blow at a specific geographic location. public domain lands Original public domain lands that have never

left federal ownership. public lands Any land and interest in land owned by the

United States. radioactivity The emission of energetic particles and/or radiation

during radioactive decay. rain forest A dense forest found in the hot, tropical areas of

the world. rain shadow An area where rainfall is low because a nearby moun-

tain range obstructs rain-bearing winds. remote sensing The process of detecting and monitoring physical

characteristics of an area by measuring its reflected and emitted radiation and without physically contacting the object.

Glossary

respiration The chemical process by which organic material is bro-

ken down, releasing energy. Ring of Fire The zone of earthquakes surrounding the Pacific Ocean

that is called the circum-Pacific belt; about 90% of the world’s earthquakes occur there. riparian areas Lands adjacent to creeks, streams, and rivers where

vegetation is strongly influenced by the presence of water. sea-level rise A rise in the surface of the sea due to increased water

volume of the ocean and/or sinking of the land. sediment Solid, unconsolidated rock and mineral fragments

that come from the weathering of rocks and are transported by water, air, or ice and form layers on the Earth’s surface; sediments can also result from chemical precipitation or secretion by organisms. seismograph A scientific instrument that detects and records vibra-

tions (seismic waves) produced by earthquakes. seismology The study of earthquakes and the structure of the Earth,

by both naturally and artificially generated seismic waves. shield volcano A volcano that resembles an inverted warrior’s shield;

it has long, gentle slopes produced by multiple eruptions of fluid lava flows. shrubland A biome that mainly contains shrubs, such as the chapar-

ral of California. snow line The lowest elevation at which snow remains from year to

year and does not melt during the summer. soil In engineering, all unconsolidated material above bedrock; in

soil science, naturally occurring layers of mineral and/or organic constituents that differ from the underlying parent material in their physical, chemical, mineralogical, and morphological character because of pedogenic processes. soil profiles The vertical arrangement of layers of soil down to

the bedrock.

211

212

Glossary

species Group of organisms that are alike, apart from minor

variations. spreading ridges Places on the ocean floor where lithospheric plates

separate and magma erupts; about 80% of the Earth’s volcanic activity occurs on the ocean floor. stratigraphy The branch of geology concerned with the formation,

composition, and order in time, and arrangement in space of sedimentary rocks. stratovolcano A steep-sided volcano built by lava flows and tephra

deposits (also called a composite volcano). subduction zone The place where two lithospheric plates come

together, one riding over the other; most volcanoes on land occur parallel to and inland from the boundary between the two plates. succession Changes that cause one community to be replaced

by another. symbiosis The relationship of two or more organisms that live

closely together to the benefit of both. tectonic plates The large, thin, relatively rigid plates that move rela-

tive to one another on the outer surface of the Earth. temperate Having a moderate climate; Earth’s temperate zone lies

between the tropics and the polar regions. terrace Part of a hillside that has been artificially leveled, usually for

growing crops. thematic map A map designed to show information on a single topic. timberline The line above which no trees grow on a mountain. topographic map A map that uses contour lines to represent the three-

dimensional features of a landscape on a two-dimensional surface. topography The natural and constructed relief of an area. Tropic of Cancer An imaginary line around Earth 1,600 miles (2,600

km) north of the equator. Tropic of Capricorn An imaginary line around Earth 1,600 miles

(2,600 km) south of the equator.

Glossary 213

tropical Referring to climatic conditions like those found in the

region on the Earth today between the Tropic of Cancer and the Tropic of Capricorn; it includes high temperature and humidity and abundant rainfall. tropical forest Forest in Earth’s tropical zone, such as tropical rain

forest or monsoon forest. tropical grassland A tropical biome in which grass is the main form

of plant life. tsunami A sea wave of local or distant origin that results from large-

scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands. tundra A biome of the far north, made up of treeless plains covered

with small plants. ultraviolet (UV) light Light that is not visible to the human eye but

which is produced in large amounts by the sun. understory A layer of plants between the ground and the canopy of

a forest. vent The opening at the Earth’s surface through which volcanic mate-

rials (lava, tephra, and gases) erupt; vents can be at a volcano’s summit or on its slopes; they can be circular (craters) or linear (fissures). viscosity Measure of the fluidity of a substance; taffy and molasses

are very viscous; water has low viscosity. volcanic avalanche A large, chaotic mass of soil, rock, and volcanic

debris moving swiftly down the slopes of a volcano; volcanic avalanches can also occur without an eruption as a result of an earthquake, heavy rainfall, or unstable soil, rock, and volcanic debris (also called a debris avalanche). volcano A vent (opening) in the Earth’s surface through which

magma erupts; it is also the landform that is constructed by the eruptive material. water table The natural level of water in the soil; in dry places, it

may be down very deep.

214

Glossary

waterfowl habitat Areas suitable for certain species of birds, such as

ducks, geese, and herons; they comprise wetlands, lakes, ponds, and reservoirs. watershed An area drained by a river. wetland Land or areas that are covered, often intermittently, with

shallow water or saturated water. wild free-roaming horses and burros All unbranded and unclaimed

horses and burros using public lands as all or part of their habitat. wilderness An area of undeveloped federal land retaining its pri-

meval character and influence, without permanent improvement or human habitation, which is protected and managed so as to preserve its natural condition. windward The side of a landmass facing the direction from which

the wind is blowing; the opposite of leeward.

Further REading Alden, P. National Audubon Society Field Guide to the Rocky Mountain States. New York: Knopf, 1999. Aldis, Rodney. Polar Lands. New York: Dillon Press, 1992. Alexander, Taylor R., et al. Botany: A Golden Science Guide. Racine, Wis.: Western Publishing Company Inc., 1970. Amsel, Sheri. A Wetland Walk. Brookfield, Conn.: Millbrook Press Inc., 1993. Arduini, Paolo, and Giorgio Teruzzi. Simon & Schuster’s Guide to Fossils. New York: Simon & Schuster, 1986. Attenborough, David. The Private Life of Plants. Princeton, N.J.: Princeton University Press, 1995. Burnie, David. Endangered Planet. Boston: Kingfisher, 2004. Cochrane, Jennifer. Plant Ecology. New York: The Bookwright Press, 1987. Collinson, Alan. Grasslands. (Ecology Watch). New York: Macmillan Children’s Group, 1992. Czerkas, S.J., and S.A. Czerkas. Dinosaurs: A Global View. New York: Mallard Press, 1991. Dowden, Anne Ophelia. Plants That Harm & Heal. New York: HarperCollins Children’s Books, 1994. Facklam, Howard, and Margery Facklam. Plants: Extinction or Survival? Hillside, N.J.: Enslow Publishers, 1990. Fenton, C.L., M.A. Fenton, P.V. Rich, and T.H. Roch. The Fossil Book: A Record of Prehistoric Life. New York: Doubleday, 1989. Fleisher, Paul. Mountain Stream. Tarrytown, N.Y.: Marshall Cavendish Corporation, 1998. Fowler, Allan. Our Living Forests. Danbury, Conn.: Children’s Press, 1999. Gerrard, John. Mountain Environments. Cambridge, Mass.: MIT Press, 1990. Greenaway, Theresa. Cycles in Nature: Plant Life. New York: Raintree Steck-Vaughn Publishers, 2001. 215

216

Further Reading

Greene, Carol. Caring for Our Forests. Springfield, N.J.: Enslow Publishers Inc., 1991. Harris, Tim. Mountains and Highlands. Austin, Tex.: Steck-Vaughn Company, 2003. Holmes, Don W. Highpoints of the United States. Salt Lake City: University of Utah Press, 2000. Knapp, Brian. Landforms. Danbury, Conn.: Grolier Educational, 2001. ———. Visual Science Encyclopedia: Plants. Danbury, Conn.: Grolier Educational, 2002. Leggett, Jeremy. Dying Forests. North Bellmore, N.J.: Marshall Cavendish, 1991. Marcus, Elizabeth. Amazing World of Plants. Mahwah, N.J.: Troll Associates, 1984. Nations, James D. Tropical Rain Forests: Endangered Environments. New York: Franklin Watts, 1988. Parker, Jane, and Steve Parker. Deserts. Danbury, Conn.: Franklin Watts, 1998. Parker, Steve, and R.L. Benor. The Practical Paleontologist. New York: Simon and Schuster/Fireside, 1990. Pipes, Rose. Coasts and Shores. Austin, Tex.: Steck-Vaughn Company, 1999. Ricciuti, Edward R. Desert. New York: Benchmark Books, 1996. Sayre, April Pulley. Grassland. New York: Twenty-First Century Books, 1994. ———. Wetland. New York: Twenty-First Century Books, 1996. Staub, Frank. America’s Wetlands. Minneapolis, Minn.: Lerner Publishing Group, 1994. Tesar, Jenny. Endangered Habitats. New York: Facts On File, 1991. ———. Shrinking Forests. New York: Facts On File, 1991. Warburton, Lois. Rain Forests. New York: Facts On File, 1991.

Further Reading

Westbrooks, R. Invasive Plants, Changing the Landscape of America: Fact Book. Washington, D.C.: Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW). 1998. Whiteman, C. David. Mountain Meteorology. New York: Oxford University Press, 2000. Williams, Brian. The Living World. Visual Factfinder. New York: Kingfisher Books, 1993.

217

Index A acid rain, 112 acids, mining and, 117, 133 Adopt-a-Horse program, 68 aesthetics, plants and, 59 agricultural resources, 57–58 agriculture conservation and, 176–178, 195 glaciers and, 63–64 impacts of, 49–51, 107, 113, 118, 196 land use and, 27–29, 46–47 water and, 125, 146 wildlife habitat and, 76, 77–78 air pollution, 111–112 alluvial fan deposits, 62–63 American West, 47–48, 74 Anasazi ruins, 45 Anchorage, AK, 94 Antiquities Act, 104, 171–173 aquifers, 27, 64, 83 aragonite, 134 Archaeological Resources Protection Act, 104 archaeology, 30, 141, 166–168 arctic regions, 19 artifacts, 42–43, 134–135 atmosphere, climate and, 10 atoms, 32 B backpacking, 130 backyard conservation mulching and, 180–181 nutrient management and, 181 overview of, 178–179 pest management and, 181–182 ponds, wetlands and, 179–180 terracing and, 182 trees and, 182–183 water resources and, 183 wildlife and, 183–185 bacteria, nitrogen cycle and, 85, 86 basalt, magnetic striping and, 9–10

bedrock, 25 Bennett, Hugh Hammond, 51 bicycles, 132 biodiversity, 20, 69, 123, 124, 127 biofuels, 59, 194–196 biogeochemical cycles carbon cycle and, 84–85 food webs and, 87–90 nitrogen cycle and, 85–87 overview of, 78–79 rock cycle and, 79–82 water cycle and, 82–84 biological weathering, 81 biomass, 59, 194–196 biomass energy, 59, 70, 194–196 biomes, 15–25 biosphere reserves, 174 Birdseye, Claude, 53 Bonneville, Lake, 36–40 boreal forests, 22–23 boron, 62 botanical resources, 59–60, 162 boundaries, tectonic, 3–4 buffalo, 74 buffer strips, 60 Burchard, Roland, 53 Bureau of Land Management (BLM), 67–68, 100–109, 140–142, 150–151, 164–165 burros, 66–68, 154–155 C calcite, caves and, 134 camping, 130, 152, 164. See also “Leave No Trace” concept campos, 123 canyons, glaciers and, 35–36 carbon cycle, 84–85, 123, 124 Carlsbad Caverns, 136, 137 caves, 134–138 CERCLA, 145 Challenger Deep, 7–8 Channel Islands National Park, 174 chlorofluorocarbons (CFCs), 196 218

Index 219

Cincinnati, OH, 63 cities, growth of, 116–117. See also urbanization Civilian Conservation Corps (CCC), 50 Clark, William, 48–49 clay, 132 climate, 10–15, 25, 26, 31–37 climate change, 68–69, 89–90, 111–112, 118, 188–189 coal, 56, 59, 71, 188 coastal resources, value of, 126–127 cold-climate forests, overview of, 22–23 communities, ecosystems as, 17–18 competition, land resources and, 74–75 composting, 194 condensation, water cycle and, 82 conifers, 22–23 conservation. See also backyard conservation of ancient places, 166–168 Dust Bowl and, 50–51 energy resources and, 71 examples of, 176–178 importance of, 192–193 “Leave No Trace” concept and, 69, 104, 168–170 soils and, 60–61 wetlands and, 69–70 consumers, 87 contour farming, 60, 61, 178 convection cells, 6–7 convergent plates, 4 copper, 56, 62 coral, 34–35, 40–42, 127 crop rotation, 60, 181–182 crust, 3, 5, 91 culture, artifacts and, 41–44 D daughter isotopes, 32 debris flows, 96, 97

deciduous forests, 20–21 decomposition, 85–86, 87 deforestation, 115, 118, 122 denitrification, 86 Department of Energy, 194–195 desertification, 52–54, 65, 120, 124, 149 deserts, 12, 13, 21–22, 61–63, 64 designated wilderness areas, 175–176 developing countries, 188 Devils Tower National Monument, 129 dinosaur tracks, 33, 141, 166–167 disturbances, ecosystems and, 18 divergent plates, 3, 91–93 domestication, 46 drinking water, 125 drought, Dust Bowl and, 50–51 drugs, 24, 59, 197 drumlins, 63 Dust Bowl, 49–51, 57 E earthquakes, 4, 91–92, 94 ecosystems, 17–18, 124, 127–128 efficiency, importance of, 192–193 electromagnetic radiation, 44–45, 160–162 emissions, increasing, 189 endangered species, 190 Endangered Species Act, 178 energy, 59, 87, 131, 191–192. See also hydroelectric energy energy resources, 70–71 entertainment, 128–131 Environmental Protection Agency (EPA), 115, 144–145 erosion causes of, 52 ecosystem disturbance and, 18 fossil record and, 33 rock cycle and, 79–81 soil health and, 27, 60, 145, 149, 180–181 weeds and, 107

220

Index

estuaries, 148 evaporation, 62–63, 83 evapotranspiration, 83 exchange pools, 79 exploration, 47–49 extinctions, 56, 68–69 F factory farming, 118 fallow fields, soils and, 60–61 farming. See agriculture federal government, 140–142 Federal Land Policy and Management Act of 1976 (FLPMA), 101–102, 141 fertilizers, 134 fire fuel loading, 159 fires, 23, 98–99, 108, 153–155, 159 fish, 125 fishing, 130, 142–143, 152 flooding, 69–70, 97–98 food webs, 18, 59–60, 87–90 forests conservation and, 151–153, 182–183, 195 deforestation and, 115, 118, 122 glaciers and, 64 as rangeland, 64 types of, 20–25 value of, 122–123 Forest Service, 100, 115, 140–142, 164–165 fossil fuels, 56, 59, 71, 188 fossil record, 33–35, 40–42, 135, 166–168 fragmentation, wildlife habitat and, 76 freshwater assets, value of, 125–126 future of land resources greenhouse effect and, 188–189 habitat loss and, 189–191 overview of, 187–188, 196 recycling, reducing, and reusing and, 191–194

seed banks and, 196–197 stewardship and, 197–198 synthetic materials and, 194–196 G Gabelich, Gary, 39, 40 garbage, 113–114 genetic engineering, 27–29 geographic information systems (GIS), 102, 119, 157–164 geologic time, 31–36 geothermal energy, 70–71, 95 glaciers, 19, 25, 35–36, 63–64 Global Positioning System (GPS), 158 golf, 133 goods and services, 121–122 government, 140–142 grain crops, 124 Grand Canyon, 49, 53 Grand Teton National Park, 172 grasslands, 23–24, 27–29, 64, 72, 123–125. See also savannah regions gravel, 37–40, 63 gravity, water cycle and, 82 Great Salt Lake, 37 greenhouse effect, 111–112, 188–189 Green River Formation, 62–63 groundwater, 61–62, 83, 117, 125 gypsum, 134 H habitats backyard conservation and, 183–185 caves as, 134 competition for land resources and, 74–78 deforestation and, 118 designated wilderness areas and, 176 future loss of, 189–191 modeling of, 159–160 rangeland as, 64 wildlife and, 68–69

Index 221

Hayden, Ferdinand V., 49 hazardous material spills, 144–145, 146 hazards. See natural hazards health, ecosystems and, 18 herbicides, weeds and, 108 herbivores, nitrogen cycle and, 85 Himalayan mountains, 4 history of land use American West and, 47–48 Dust Bowl and, 49–51 geologic time, climatology and, 31–36 Lake Bonneville and, 36–40 land use development and, 46–47 overgrazing, desertification and, 51–54 overview of, 30–31 petroglyphs and, 42–46 red horn coral fossils and, 40–42 Soil Conservation Act and, 51 horizons, soils and, 26 human impacts. See impacts humus, 26, 86 hunter-gatherers, 46–47 hydroelectric energy, 70, 125–126 hydrologic cycle, 59, 82–84, 183 I Ice cap climates, 15 impacts, 115–120, 143–144, 196. See also pollution Industrial Revolution, 47, 111, 116 insects, 181–182, 189 International Biosphere Reserves, 174 invasive species. See also weeds agricultural resources and, 57 cities and, 127 impacts of, 146 overgrazing and, 52 stewardship and, 148 urbanization and, 76–77 wildlife and, 78 iron, 56, 62

irrigation, 44, 46 isotope analysis, 31–33 J Johnston, Velma, 67 K knapweed, 108 Kyoto Protocol, 187 L Laguna Beach, CA, 94 landfills, 114, 144 landslides, 94, 95–97 Landslides Hazards Program, 97 land-use planning, 90–91, 155–157, 163–164 lava, 8–9, 79–80, 93 leaching, deserts and, 61 leafy spurge, 108–109 “Leave No Trace” concept, 69, 104, 168–170 Leopold, Aldo, 174 Lewis, Meriwether, 48–49 lidar, 45 lightning, wildfires and, 99 limestone, 34 lithosphere, 3, 5 livestock, 123. See also overgrazing; rangeland M magma, 80, 93 magnetic striping, 9–10 Mammoth Cave, 134, 137 management federal government and, 140–142 land stewardship and, 147–150 modeling, planning and, 155–157 overview of, 139–140 planning and, 163–164 of public lands, 150–155 tools for, 157–163 mantle, 5–7

222

Index

mapping, 102, 109–111, 119, 157–164 Mariana Trench, 7–8 marine/island regions, 21, 143 medicines, 24, 59, 197 Mediterranean climates, 13–15 Mesa Verde National Park, 171 micronutrients, 181 microorganisms, soils and, 26 middens, 42, 135 migration corridors, 76 mineral resources BLM and, 140–141 deserts and, 61–62 forests and, 123 impacts of, 144 overview of, 70–72 pollution and, 115, 117, 133 public lands and, 131–133, 150–151 water quality and, 146 modeling, 119, 155–157 mountain regions, overview of, 18–20 mudflows, volcanic, 93, 94. See also landslides mulching, 180–181 multiple use management, 73–78, 102–103, 139–140. See also management municipal solid waste, 113–114 mustangs, 66–68, 154–155 N National Historic Preservation Act, 104 National Oceanic and Atmospheric Administration (NOAA), 178 National Park Service (NPS), 100, 140–142, 170–175. See also individual parks Native American Graves Protection and Repatriation Act, 104 natural hazards earthquakes, 4, 91–93 flooding, 69–70, 97–98 GIS and, 162

landslides, 95–97 overview of, 90–91 volcanos, 8–9, 25, 48, 79–82, 93–95 wildfires, 98–99 nitrogen cycle, 85–87 nonrenewable energy, 71 nonrenewable resources, 55–56 northern coniferous forests, 22–23 noxious weeds, 108 nutrient management, 181 nutrients, soils and, 27 O oil spills, 114 organisms, soils and, 25, 26, 89 overgrazing, 51–54, 60–61, 120, 124–125, 143–144 P Pacific Ring of Fire, 9, 93 packaging, 193 paleontology, 33–35, 40–42, 135, 166–168 Pangaea, 1–2 parent isotopes, 32 permafrost, 20 pest management, 112–113, 181–182 petroglyphs, 42–46, 152 petroleum sources, 63, 101, 131 photosynthesis, 59, 85 planning. See land-use planning plants. See also botanical resources; invasive species; weeds biofuels and, 59, 194–196 biomass energy and, 59, 70 cities and, 127–128 destruction of, 189 food webs and, 87 GIS mapping and, 159 origins of major groups of, 34 remote sensing and, 162 seed banks and, 196–197 soils and, 90

Index 223

urbanization and, 76–77 wildfires and, 155 plate boundary zones, 9 plate tectonics, 1–4, 5–10, 91–93 plowing, 46 pollination, 189 pollution agriculture and, 118, 125 food webs and, 89 impacts of, 146 mining and, 133, 144 overview of, 111–115 plants and, 128 of rivers, 196 soils and, 26, 27, 90 wetlands and, 69, 70 wildlife and, 78 population growth, 116–117 Powell, John Wesley, 49 prairies. See grasslands precipitation, 10–15, 21–25 preparedness, earthquakes and, 92 profiles, soils and, 26 protected areas, 170–176 public lands, 100–109, 131–133, 150–155 purple loosestrife, 108 R radioactive decay, 7 radioactivity, 31–33 rainfall, 10–15, 21–25 rain forests, 189–190 rangeland, 27–29, 52–54, 64–68, 106, 120 recovery plans, 144, 178 recreation aquatic, 77 coastal areas and, 126 freshwater and, 126 images of, 19, 75 impacts of, 76 land use and, 128–131, 134–138 public land management and, 150

rangeland and, 65 stewardship and, 149, 152, 155 recycling, 114, 191–194 remote sensing, 44–45, 160–162 renewable energy, 70–71 renewable resources, 55–56, 151–153 residence times, 79 residual heat, 7 resource allocation, 163–164 respiration, 85 reuse, 191–194 Ring of Fire, 9, 93 riparian areas, 149–150 rivers, 37–40, 47, 196 roads, 76, 77, 116, 145, 153–154 rock cycle, 79–82 runoff, soils and, 61 S saline minerals, 62 salts, 37–40, 63 San Andreas Fault, 4 sand, 37–40, 63, 127 savannah regions, 25, 64 scale, maps and, 111 seafloor spreading, 3, 7 sedimentary rocks, 81 sedimentation, weeds and, 107 sediments, glaciers and, 63 seed banks, 196–197 sliding plates, 4, 91–93 Soil Conservation Act, 51 Soil Conservation Service (SCS), 51 Soil Erosion Service (SES), 50, 51 soils Dust Bowl and, 49–51, 57 flooding and, 84, 98 food webs and, 89–90 grasslands and, 23 importance of, 25–27 nutrients and, 181 as resource, 57, 60–61 stewardship and, 149 volcanic, 93

224

Index

solar energy, 82, 87 speleothems, 134, 136, 137 sprawl, 54, 58, 76–77, 118–120 spreading plates, 3, 91–93 springs, 83 stewardship, 147–150, 197–198 stratigraphy, 33–34 strip cropping, soils and, 60, 61 striping, 9–10 subduction zones, 4, 8, 91–93 succession, 98 Sudanese desert, 45 surveys, 48–49, 51 sustainable yield, 56 synthetic materials, 194–196 T taiga, 22–23 tailing pits, 117, 133, 144 Taxol, 20 tectonics, 1–4, 5–10, 91–93 temperate forests, 20–21 terracing, 60, 61, 182 thistle, 106, 109 tilling, soils and, 60 time, 25–26, 31–36, 79, 89–90, 158 titanium, 133 toadflax, 109 tools, 102, 119, 157–164 topographic maps, 109–111 topography, 25, 26, 89 trace fossils, 33 trade winds, climate and, 10–15 transform plates, 4, 91–93 transpiration, 59, 83 transportation, 76–77, 116, 118–120, 145, 153–154 trenches (oceanic), 4, 7–8 tropical dry forests, overview of, 22 tropical rain forests, 24–25, 189–190 tropical steppe climate, 13 tundra regions, 15, 20, 64

U UNESCO, 174 United Nations Environment Programme (UNEP), 143, 196 Urban Dynamics Research (UDR) program, 119 urban environments, value of, 127–128 urbanization, 54, 58, 76–77, 118–120 U.S. Department of Agriculture (USDA), 197 U.S. Fish and Wildlife Service (FWS), 140–142, 174, 178 U.S. Forest Service, 100, 115, 140–142, 164–165 U.S. Geological Survey (USGS), 109–111, 119, 163 U-shaped valleys, 35–36 V volcanos, 8–9, 25, 48, 79–82, 93–95 W waste management, 145–146, 147, 165 water cycle, 59, 82–84, 123, 183 water hyacinths, 109 water quality, 144, 146 weathering, 25, 81 weeds, 105–109, 112–113, 146, 148. See also invasive species westerly winds, 11–12 wetlands, 69–70, 78, 117, 125, 179–180 Wild and Scenic Rivers Act, 104 Wilderness Act, 104, 175 wildfires, 23, 98–99, 108, 153–155, 159 “Wild Horse Annie,” 67 wildlife caves and, 134, 137–138 cities and, 128 conservation and, 68–69, 169–174, 175–176, 183–185

Index 225

endangered species and, 190 GIS mapping and, 157–158, 159 landfills and, 114 rangeland and, 64–65 resource competition and, 74–78 roads and, 145 stewardship and, 154–155, 165, 191 weeds and, 146 wetlands and, 70 wildfires and, 98 Wildlife Refuge System, 174

wild mustangs, 66–68, 154–155 winds, 10–15 World Conservation Union, 187 World Wildlife Fund, 187 X xerophytes, conservation and, 183 Y Yellowstone fires, 98 yield, sustainable, 56 Yosemite National Park, 129, 171

About the Author Julie Kerr Casper holds B.S., M.S., and Ph.D. degrees in earth science with an emphasis on natural resource conservation. She has worked for the United States Bureau of Land Management (BLM) for nearly 30 years and is primarily focused on practical issues concerning the promotion of a healthier, better-managed environment for both the short- and long-term. She has also had extensive experience teaching middle school and high school students over the past 20 years. She has taught classes, instructed workshops, given presentations, and led field trips and science application exercises. She is the author of several award-winning novels, articles, and stories.

226

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