STUDENT EDITION SAMPLER ENVIRONMENTAL

SUSTAINING YOUR WORLD

G. TYLER MILLER • SCOTT E. SPOOLMAN Transport Students into Environmental Science with National Geographic Learning ENVIRONMENTAL

Elevate Environmental Science instruction with the first high school program built with National Geographic images and Explorers. Promote scientific understanding of environmental issues SUSTAINING YOUR WORLD Develop real-world science practices with Explorers as examples Encourage critical thinking skills

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Teach the 3-dimensions with instruction for the ON ASSIGNMENT National Geographic Disciplinary Core Ideas, Science and Engineering photographer Carsten Peter accompanied a group of explorers to document the Practices, and Crosscutting Concepts untouched subterranean beauty of Incorporate engineering with comprehensive Vietnam’s Hang Son Doong. The enormous cave is part of a national park, which was unit projects named a World Heritage site in 2003. Although longer and deeper caves have Multi-disciplinary approach with standards from been discovered, none are as large as Hang earth, life, physical, and technology sciences Son Doong, which could easily fit several 40-story skyscrapers.

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ENVI_SCI_TITLEPAGE_.indd 3 2/4/16 4:26 PM About the Authors

G. TYLER MILLER

G. Tyler Miller has written 62 textbooks He describes his hopes for the future as follows. for introductory courses in environmental If I had to pick a time to be alive, it would be the next science, basic ecology, energy, and “ environmental chemistry. Since 1975, Miller’s 75 years. Why? First, there is overwhelming scientific books have been the most widely used evidence that we are in the process of seriously textbooks for environmental science in the degrading our own life-support system. In other words, United States and throughout the world. They we are living unsustainably. Second, within your have been used by almost 3 million students lifetime we have the opportunity to learn how to live Copyright © 2017 National Geographic Learning, a part and have been translated into eight languages. more sustainably by working with the rest of nature, of Cengage Learning Miller has a professional background in as described in this book. ALL RIGHTS RESERVED. No part of this work covered chemistry, physics, and ecology. He has a I am fortunate to have three smart, talented, and by the copyright herein may be reproduced or PhD from the University of Virginia and has “ wonderful sons—Greg, David, and Bill. I am especially Acknowledgments distributed in any form or by any means, except as received two honorary doctoral degrees for permitted by U.S. copyright law, without the prior his contributions to environmental education. privileged to have Kathleen as my wife, best friend, Grateful acknowledgment is given to the authors, written permission of the copyright owner. He taught college for 20 years, and developed and research associate. It is inspiring to have a artists, photographers, museums, publishers, and one of the nation’s first environmental brilliant, beautiful (inside and out), and strong woman agents for permission to reprint copyrighted material. “National Geographic,” “National Geographic Society” studies programs, before deciding to write Every effort has been made to secure the appropriate and the Yellow Border Design are registered environmental science textbooks full-time who cares deeply about nature as a lifemate. She is my permission. If any omissions have been made or if trademarks of the National Geographic Society in 1975. hero. I dedicate this book to her and to the earth.” corrections are required, please contact the Publisher. ® Marcas Registradas For product information and technology assistance, Photographic Credits contact us at Customer & Sales Support, 888-915-3276 SCOTT E. SPOOLMAN Cover Carsten Peter/National Geographic Creative. For permission to use material from this text or Scott Spoolman has more than 30 years of Spoolman has the following to say about his collaboration Inside Front Cover Can Yesil/Shutterstock.com Title product, submit all requests online at experience in educational publishing. He has with Tyler Miller. Page (bg) Carsten Peter/National Geographic Creative. worked with Tyler Miller first as a contributing www.cengage.com/permissions I am honored to be working with Tyler Miller as a v (tl) Shah Selbe. vi (cl) Stephen Saks/Lonely Planet editor and then as coauthor of Living in the “ coauthor to continue the Miller tradition of thorough, Images/Getty Images. viii (cr) Karine Aigner/Meet Your Further permissions questions can be emailed Environment, Environmental Science, and clear, and engaging writing about the vast and Neighbours/iLCP. 3 (tr) Shah Selbe. (cr) Karine Aigner/ [email protected] Sustaining the Earth. With Norman Myers, he Meet Your Neighbours/iLCP. (br) Stephen Saks/Lonely coauthored Environmental Issues and Solutions: complex field of environmental science. I share Tyler A Modular Approach. Planet Images/Getty Images. 64 Paul Harris/AML National Geographic Learning | Cengage Learning Miller’s passion for ensuring that these textbooks and 1 N. State Street, Suite 900 Images/Getty Images. 67 (t, bl, br) Robin Moore. 68 Spoolman holds a master’s degree in science their multimedia supplements will be valuable tools Chicago, IL 60602 (bl, br) U.S. Department of the Interior U.S. Geological journalism from the University of Minnesota. for students and instructors. To that end, we strive to He has authored numerous articles in the Survey. 70 (t) Frans Lanting/National Geographic Cengage Learning is a leading provider of customized introduce this interdisciplinary field in ways that will Creative. 74 (bg) Frans Lanting/National Geographic fields of science, environmental engineering, learning solutions with office locations around the politics, and business. He has also worked as a be informative and sobering, but also tantalizing Creative. 77 (t) Eye of Science/Science Source. 79 (b) globe, including Singapore, the United Kingdom, consulting editor in the development of over and motivational. Roy Toft/National Geographic Creative. 84 (bg) Peter Australia, Mexico, Brazil, and Japan. Locate your local 70 college and high school textbooks in fields McBride/National Geographic Creative. 91 (bg) 2011 office at www.cengage.com/global. of the natural and social sciences. “If the flip side of any problem is indeed an opportunity, Drew Fulton. 92 (cl) Sue Cunningham Photographic/ then this truly is one of the most exciting times in Alamy Stock Photo. 93 (t) NASA Goddard Space Flight Visit National Geographic Learning online at In his free time, he enjoys exploring the forests and waters of his native Wisconsin history for students to start an environmental career. Center Image by Reto Stöckli (land surface, shallow NGL.Cengage.com along with his family—his wife, environmental Environmental problems are numerous, serious, and water, clouds). Enhancements by Robert Simmon Visit our corporate website at www.cengage.com educator Gail Martinelli, and his children, Will daunting, but their possible solutions generate exciting (ocean color, compositing, 3D globes, animation). Data and Katie. and technical support: MODIS Land Group; MODIS ISBN: 9781305637429 new career opportunities. We place high priorities on inspiring students with these possibilities, challenging Science Data Support Team; MODIS Atmosphere Printed in the USA. Group; MODIS Ocean Group Additional data: USGS them to maintain a scientific focus, pointing them EROS Data Center (topography); USGS Terrestrial RR Donnelley, Willard, Ohio, USA toward rewarding and fulfilling careers, and in doing Remote Sensing Flagstaff Field Center (Antarctica); Print Number: 01 so, working to help sustain life on the earth. Defense Meteorological Satellite Program (city lights). ” 205 (b) Leonardo Patrizi/iStock/Getty Images. Print Year: 2016

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ENVI_SCI_Copyright.indd 2 2/4/16 4:24 PM ENVI_SCI_AUTHORS.indd 3 2/4/16 4:30 PM Jim Estes Andrés Ruzo Ecologist and Evolutionary Biologist Geologist CONTENTS National Geographic Grantee National Geographic Young Explorer John Francis SPECIAL FEATURE CHAPTER 2 National Geographic Behavioral Ecologist Enric Sala Into the Okavango with National Geographic Consultant National Geographic Grantee and Marine Ecologist SCIENCE, MATTER, ENERGY, AND SYSTEMS Vice President for Research, National Geographic Christopher Thornton Conservation, and Exploration Explorer-in-Residence EXPLORERS AT WORK New Paths to Engaging Vice-Chair, Committee for Research Science, with Nalini Nadkarni and Exploration Christopher Golden Joel Sartore Ecologist and Epidemiologist Photographer CASE STUDY Experimenting with a Forest National Geographic National Geographic Fellow Emerging Explorer 2.1 What Do Scientists Do? National Geographic Anna Savage Engineering Focus: What Is Engineering? Featured Explorers Jerry Glover Evolutionary Geneticist Agroecologist National Geographic EXPLORERS AT WORK John Francis Robert Ballard National Geographic Young Explorer 2.2 What Is Matter? Ocean Explorer Emerging Explorer National Geographic Çağan Hakkı Şekercioğlu 2.3 What Is Energy? Explorer-in-Residence Jane Goodall Ornithologist and Primatologist Conservation Ecologist 2.4 What Are Systems? Kamaljit S. Bawa National Geographic National Geographic Conservation Biologist Explorer-in-Residence Emerging Explorer TYING IT ALL TOGETHER The Hubbard Brook National Geographic Grantee Yu-Guo Guo Shah Selbe Forest Experiment Vitor Osmar Becker Chemist Engineer and Conservation Conservationist National Geographic Technologist SAMPLED PAGES National Geographic Grantee Emerging Explorer National Geographic Emerging Explorer Steve Boyes Caleb Harper CHAPTER 3 Conservation Biologist Urban Agriculturalist Hayat Sindi National Geographic National Geographic Science Entrepreneur ECOSYSTEM DYNAMICS Emerging Explorer Emerging Explorer National Geographic EXPLORERS AT WORK Eco-Paradise at Serra Emerging Explorer Dan Buettner Zeb Hogan Bonita, with Vitor Becker Author Ecologist and Photographer Tristram Stuart National Geographic Fellow National Geographic Author and Campaigner CASE STUDY Disappearing Tropical Rain Forests Fellow and Emerging Explorer National Geographic UNIT 1 3.1 What Are Earth’s Major Spheres, and How Do Jennifer Burney Emerging Explorer ECOLOGY AND ECOSYSTEMS Environmental Scientist Osvel Hinojosa Huerta They Support Life? National Geographic Conservationist Gregg Treinish CHAPTER 1 Science Focus: Nutrient Cycling Emerging Explorer National Geographic Adventurer and Conservationist THE ENVIRONMENT AND SUSTAINABILITY Emerging Explorer National Geographic 3.2 What Are the Major Ecosystem Components? Alizé Carrère Emerging Explorer EXPLORERS AT WORK Reconnecting People with Writer and Biologist Thomas E. Lovejoy Engineering Focus: Nature’s Cleanup Crew National Geographic Nature, with Juan Martinez Tropical and Conservation Biologist Anand Varma 3.3 What Happens to Energy in an Ecosystem? Young Explorer National Geographic Fellow Natural History Photographer CASE STUDY The Greening of American Schools National Geographic 3.4 What Happens to Matter in an Ecosystem? T.H. Culhane Juan Martinez Young Explorer 1.1 What Are Some Key Factors of Urban Planner Environmentalist Science Focus: Water National Geographic Blackstone Katey Walter-Anthony Sustainability? National Geographic 3.5 How Do Scientists Study Ecosystems? Innovation Challenge Grantee Emerging Explorer Aquatic Ecologist and Biogeochemist National Geographic 1.2 How Are Our Ecological Footprints EXPLORERS AT WORK Thomas E. Lovejoy Leslie Dewan Nalini Nadkarni Emerging Explorer and Blackstone Affecting Earth? Science Focus: Testing Planetary Boundaries Nuclear Engineer Forest Ecologist and Science Innovation Challenge Grantee National Geographic Communicator 1.3 What Causes Environmental Problems and TYING IT ALL TOGETHER The Energy Cost of Emerging Explorer National Geographic Grantee Edward O. Wilson Why Do They Persist? Cutting Rain Forests Biologist and Author Dennis Dimick Erin Pettit National Geographic 1.4 What Is an Environmentally Sustainable Conservationist UNIT 1 ENGINEERING PROJECT Glaciologist and Geophysicist Hubbard Award recipient Society? National Geographic Editor National Geographic Design a Method for Treating Contaminated Soil Emerging Explorer Xiaolin Zheng EXPLORERS AT WORK Dennis Dimick Sylvia Earle Nanoscientist Oceanographer Sandra Postel National Geographic TYING IT ALL TOGETHER The Greening of the American National Geographic Freshwater Conservationist Emerging Explorer Mindset Explorer-in-Residence National Geographic Fellow

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ENVI_SCI_EXPLORERS.indd 4 2/1/16 3:33 PM ENVI_SCI_TOC_Sampler.indd 5 3/1/16 3:21 PM CONTENTS

UNIT 2 6.1 What Factors Influence Climate? 7.2 What Role Do Humans Play in the Loss of caSe Study Growing Power—An Urban BIODIVERSITY Science Focus: Greenhouse Gases Species and Ecosystem Services? Food Oasis Science Focus: Honeybee Losses CHAPTER 4 6.2 What Are the Major Types of Terrestrial 9.1 What Is Food Security? BIODIVERSITY AND EVOLUTION Ecosystems? 7.3 How Can We Sustain Wild Species and 9.2 How Is Food Produced? Science Focus: Desert Adaptations EXPLORERS AT WORK Fighting a Deadly Ecosystem Services? EXPLORERS AT WORK Alizé Carrère 9.3 How Are Environmental Issues and Food Frog Disease, with Anna Savage Science Focus: Wildlife Forensics Production Connected? 6.3 What Are the Major Types of Marine tying it all together Colony Collapse CASE STUDY Amphibians at Risk Science Focus: Soil Science Ecosystems? Disorder 4.1 What Is Biodiversity and Why Is It Important? explorerS at Work Jerry Glover 6.4 What Are the Major Types of Freshwater Science Focus: Insects and Ecosystem 9.4 How Can Society Manage Agricultural Pests Ecosystems? chapter 8 Services More Sustainably? TYING IT ALL TOGETHER Coral Reef Recovery SuStaining biodiverSity: an ecoSyStemS 4.2 What Roles Do Species Play in Ecosystems? approach 9.5 What Are Sustainable Solutions to Food UNIT 2 ENGINEERING PROJECT 4.3 How Does Life on Earth Change Over Time? Production? Design a System to Assess a Local Species explorerS at Work Protecting Biodiversity EXPLORERS AT WORK E.O. Wilson One Bird at a Time, with Çağan Şekercioğlu tying it all together Sustainability Starts With You 4.4 What Factors Affect Biodiversity? SPECIAL FEATURE caSe Study Costa Rica—A Global Science Focus: Geological Processes and Partners in Sustainability: Nature Museums and Conservation Leader Biodiversity Preserves chapter 10 8.1 How Can People Manage Forests More Water reSourceS and Water pollution TYING IT ALL TOGETHER Piecing Together the Sustainably? Puzzle of Chytrid Disease Science Focus: The Value of Ecosystem explorerS at Work Rescuing the Colorado Services River Delta, with Osvel Hinojosa Huerta CHAPTER 5 8.2 How Can People Manage Grasslands More caSe Study The Colorado River Story SPECIES INTERACTIONS, SUCCESSION, AND Sustainably? 10.1 Why Is Fresh Water in Short Supply? POPULATION CONTROL 8.3 How Can People Manage Protected Lands 10.2 How Can People Increase Freshwater EXPLORERS AT WORK Sea Otters Step Up, with More Sustainably? Supplies? Jim Estes 8.4 How Can the Ecosystems Approach Help Science Focus: Aquifer Depletion in the CASE STUDY The Southern Sea Otter: A Species Protect Terrestrial Biodiversity? United States in Recovery explorerS at Work Kamaljit Bawa 10.3 How Can People Use Freshwater Resources 5.1 How Do Species Interact? 8.5 How Can the Ecosystems Approach Help More Sustainably? 5.2 How Do Ecosystems Respond to Changing Protect Aquatic Biodiversity? explorerS at Work Sandra Postel Conditions? tying it all together Rates of Tropical 10.4 How Can People Reduce Water Pollution? UNIT 3 5.3 What Limits the Growth of Populations? Forest Loss engineering Focus: Working with Nature to SUSTAINING BIODIVERSITY Treat Sewage EXPLORERS AT WORK Zeb Hogan unit 3 engineering project CHAPTER 7 TYING IT ALL TOGETHER Southern Sea Otters Design a Solar Cooker tying it all together Saving the Colorado SAVING SPECIES AND ECOSYSTEM SERVICES Face an Uncertain Future River EXPLORERS AT WORK Where Are the UNIT 4 Honeybees? with Anand Varma CHAPTER 6 ENVIRONMENTAL QUALITY chapter 11 geology and nonreneWable mineral ECOSYSTEMS AND CLIMATE CASE STUDY A Honeybee Mystery chapter 9 reSourceS EXPLORERS AT WORK Saving the Last Wild 7.1 What Causes Extinction and What Are Its Food, Soil, and peSt management explorerS at Work Better Batteries for Places in the Ocean, with Enric Sala Impacts? explorerS at Work Sustainable Agriculture: Is EXPLORERS AT WORK Joel Sartore Electric Cars, with Yu-Guo Guo CASE STUDY The Importance of Coral Reefs It Possible? with Jennifer Burney

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caSe Study The Importance of Rare Earth 13.2 What Are Sources of Renewable Energy? 14.4 How Can Cities Become More Sustainable? CHAPTER 17 Metals explorerS at Work Xiaolin Zheng EXPLORERS AT WORK Caleb Harper SOLID AND HAZARDOUS WASTE Engineering Focus: Curitiba’s Transportation 11.1 How Do Geological Processes Relate to 13.3 How Can Society Transition to More EXPLORERS AT WORK The Social Impacts of Food System Society and the Environment? Sustainable Energy Practices? Waste, with Tristram Stuart engineering Focus: Green City TYING IT ALL TOGETHER Analyzing Population 11.2 What Are Earth’s Mineral Resources and CASE STUDY E-Waste—An Exploding Problem How Long Might Reserves Last? tying it all together Wind Power and Growth 17.1 What Are Problems Related to Solid and explorerS at Work Bob Ballard Sustainability Hazardous Waste? CHAPTER 15 11.3 What Are the Environmental Effects of Using unit 4 engineering project 17.2 How Should Solid Waste be Handled? Mineral Resources? Design a Wind-Powered Generator HUMAN HEALTH Science Focus: Bioplastics EXPLORERS AT WORK Low-Tech Diagnostics, 11.4 How Can Society Use Mineral Resources EXPLORERS AT WORK T.H. Culhane More Sustainably? Special Feature with Hayat Sindi Citizen Science and National Geographic’s 17.3 How Should Hazardous Waste be Handled? Science Focus: The Nanotechnology CASE STUDY Mercury’s Toxic Effects BioBlitzes Revolution 17.4 How Can Society Transition to a Low-Waste 15.1 What Major Health Hazards Do We Face? Economy? tying it all together Rare Earth Metals and EXPLORERS AT WORK Dan Buettner Sustainability TYING IT ALL TOGETHER Eliminating Food Waste 15.2 What Types of Biological Hazards Do We Face? chapter 12 Science Focus: Genetic Resistance to CHAPTER 18 nonreneWable energy reSourceS Antibiotics ENVIRONMENTAL ECONOMICS, POLITICS, AND WORLDVIEWS explorerS at Work Safer Nuclear Energy, 15.3 What Types of Chemical Hazards with Leslie Dewan Do We Face? EXPLORERS AT WORK Adventurers and Scientists Science Focus: The Controversy Over BPA for Conservation (ASC), with Gregg Treinish caSe Study The Keystone XL Pipeline TYING IT ALL TOGETHER Staying Safe CASE STUDY The United States, China, and 12.1 What Is Net Energy and Why Is It Sustainability Important? CHAPTER 16 18.1 How Are Economic Systems Related to the 12.2 What Are the Advantages and Disadvantages AIR POLLUTION, CLIMATE CHANGE, Biosphere? of Using Fossil Fuels? AND OZONE DEPLETION Science Focus: Biosphere 2–A Lesson explorerS at Work Katey Walter- In Humility Anthony EXPLORERS AT WORK The Big Melt, with Erin Pettit 18.2 How Can People Use Economic Tools to 12.3 What Are the Advantages and Disadvantages UNIT 5 Address Environmental Problems? of Using Nuclear Energy? ENVIRONMENTAL CONCERNS CASE STUDY Melting Ice in Greenland chapter 14 18.3 How Can Society Enact More Sustainable Science Focus: Nuclear Fission Reactors 16.1 What Are the Major Air Pollution Problems? and Just Environmental Policies? tying it all together Life with Fossil Fuels human population and urbanization Science Focus: Indoor Air Pollution EXPLORERS AT WORK Jane Goodall explorerS at Work The People-Planet Link, 16.2 What Are the Effects of Climate Change? 18.4 How Can Society Live More Sustainably? chapter 13 with Christopher Golden EXPLORERS AT WORK Sylvia Earle reneWable energy reSourceS caSe Study Population Seven Billion Science Focus: Using Models to Predict TYING IT ALL TOGETHER A Sustainable World Change explorerS at Work The Boiling River, with 14.1 How Many People Can Earth Support? UNIT 5 ENGINEERING PROJECT Andrés Ruzo Science Focus: The Population Debate 16.3 How Can People Slow Climate Change? Design a Carbon-Capturing Device Engineering Focus: Carbon Capture caSe Study The Potential for Wind Power in the 14.2 What Factors Influence Human Population United States Growth? 16.4 How Can People Reverse Ozone Depletion?

13.1 Why Is Energy Efficiency an Important 14.3 What Are the Effects of Urbanization on the TYING IT ALL TOGETHER Melting Ice and Energy Resource? Environment? Sustainability

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ENVI_SCI_TOC_Sampler.indd 8 2/1/16 4:56 PM ENVI_SCI_TOC_Sampler.indd 9 3/2/16 10:11 AM CHAPTER 3 ECOSYSTEM DYNAMICS

AmAzoniA, a region loosely defined as the Amazon River Basin, covers an area of land KEY QUESTIONS about the size of the 48 contiguous United States. A tenth of Earth’s species are thought 3.1 What are Earth’s major spheres, and how 3.3 What happens to energy in an ecosystem? do they support life? to live in Amazonia, which includes half of the planet’s tropical rain forests. People have 3.4 What happens to matter in an ecosystem? 3.2 What are the major ecosystem lived in this region for at least 13,000 years. In the past 50 years, however, human activity 3.5 How do scientists study ecosystems? components? has destroyed close to 20% of Amazonia’s rain forest. 64 The Nanay River in Peru is one of the Amazon River’s many tributaries. 65

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070-103_ES_SE_37429_U1_C03.indd 64 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 65 1/29/16 4:53 PM Vitor Becker researches hummingbirds and insects at Serra Bonita, a nature ExPlORERS AT WORK reserve in the Atlantic Forest. Today only 8% of the Atlantic Forest remains—another reason why protecting places like Serra Bonita is so important. Eco-Paradise at Serra Bonita with National Geographic Explorer Vitor Becker

Vitor Becker takes a few moments each day to do Despite that, the family plans to expand the something that hardly anyone else in the world can reserve—and is committed to education too. The do: He feeds a buzzing flock of tiny hummingbirds research center at Serra Bonita holds laboratories, from the palm of his hand. As you might imagine, this collection rooms, and a library, and supports many isn’t something that happens in a suburban backyard, research projects that yield new information nearly but at Serra Bonita, a nearly-2,225 hectare (5,000 every day. acre) nature reserve named for the Serra Bonita Mountain in the Atlantic Forest of Brazil. Hummingbirds aren’t Becker’s only concern—there are also the thousands of moth species he has About the Atlantic Forest: There’s good news and identified at Serra Bonita. Check out online videos on bad news. It’s one of the most diverse biomes in the Serra Bonita, and you’ll find howler monkeys sitting world. It is also one of the most destroyed in Brazil— on his shoulders. And, though you won’t see them in only 8% of its original forests remain. Still, the region the videos, Becker knows puma prowl through the continues to have very high species diversity. In fact, reserve, now free from threat by hunters. protected areas like Serra Bonita are a refuge for thousands of species not found anywhere else in the The Serra Bonita website offers ideas for how to world. This lush rain forest and the species it nurtures get involved in this great project, but there are lead Becker to call Serra Bonita an “eco-paradise.” many ways to take up the causes of ecosystem conservation and species preservation. You could Dr. Becker studied forestry and trained as an start by asking questions about your own region. entomologist, which is a scientist who studies What plants and animals live there, and are they insects. He, his wife, and their daughter—with help thriving—or just barely surviving? Consider starting a from National Geographic and many others—all work citizen science project to identify species in the area. to maintain the reserve. Think about these numbers: Look for ways you can help and then set out to do it. More than 350 bird species, roughly 1,200 vascular plant species, and more than 70 frog species have Thinking Critically been identified at Serra Bonita. Protecting them is no Draw Conclusions Even though only 8% of the original small task. The Brazilian rain forest is often a difficult forests remain, the Atlantic Forest is still considered one of place for conservationists to work because of illegal the most diverse regions on Earth. Can you conclude from logging operations and other threats. these facts that the loss of forests has had little effect so far on the number of species found there? Why or why not?

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070-103_ES_SE_37429_U1_C03.indd 66 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 67 1/29/16 4:53 PM CASE STUDY 3.1 What Are Earth’s Major extends up to 6 kilometers (4 miles). Life in the Spheres, and How Do They atmosphere has evolved to tolerate the temperature Disappearing Tropical Rain Forests ranges and composition of gases only within the Support Life? Tropical rain forests support an Removing tropical rain forests become dryer, less diverse troposphere. incredible variety of life. They reduces Earth’s vital biodiversity, tropical grasslands. The presence The stratosphere is the atmospheric layer above CORE IDEAS AND SKIllS cover only about 7% of Earth’s or the planet’s variety of species of grasslands decreases rainfall the troposphere. Although nothing lives in the • Describe the four major spheres that land surface but contain half of the and the habitats where they in nearby forests, which further stratosphere, this layer has a direct impact on life support life on Earth. plant and animal species found on live. (See Chapter 4 for more weakens them. at the surface. The lower stratosphere contains a • Understand how nutrients cycle and energy flows relatively high concentration of ozone (O ), which is land. These lush forests are warm about biodiversity.) Destroying In this chapter, you will 3 through ecosystems. and humid year-round because of the habitats of plant and animal examine the living and nonliving called the ozone layer. The ozone layer absorbs more their daily rainfall and nearness to species often results in their components of ecosystems and KEY TERMS than 95% of the sun’s harmful UV radiation. It acts as the Equator. The biodiversity of extinction. When the forest loses how they function. You will learn geosphere stratosphere greenhouse a global sunscreen that allows life to exist on Earth’s tropical rain forests makes them a key species, it can have a ripple how ecosystems support life, how atmosphere hydrosphere effect surface. troposphere biosphere an excellent natural laboratory effect that leads to the loss of ecologists study the interactions Three more atmospheric layers extend for for the study of ecosystems. other species. within and among different hundreds of kilometers beyond the stratosphere: the An ecosystem is one or more Destroying tropical rain ecosystems, and the importance of Earth’s Spheres Function As a mesosphere, the thermosphere, and the exosphere. communities of organisms that forests also accelerates global maintaining ecosystem integrity. life-Support System Together, these five layers of the atmosphere protect interact with one another and their warming. Without tropical rain Healthy tropical rain forests like Earth from the extremes of space. Earth’s “life-support system” is based on the nonliving environment. forests, the atmosphere warms, the one preserved at Serra Bonita interaction among four planetary systems, or To date, human activities have leading to climate change. Why? are examples of sustainably FigurE 3-2 spheres: the atmosphere, hydrosphere, geosphere, destroyed or disturbed more Eliminating large areas of trees functioning ecosystems. Earth’s Spheres Earth consists of a land sphere (geosphere), and biosphere (Figure 3-2). The natural capital than half of Earth’s tropical rain means there are fewer plants to an air sphere (atmosphere), a water sphere (hydrosphere), and a As You Read Think about an (resources and ecosystem services) on which life life sphere (biosphere). forests. People continue clearing remove carbon dioxide (CO ) 2 ecosystem where you live. depends is the product of Earth’s spheres and energy the forests to grow more crops, during photosynthesis. Carbon Consider what makes it unique, from the sun. graze more cattle, and build dioxide is a gas that contributes as well as what it might have The Geosphere The geosphere consists of more settlements. Ecologists to atmospheric warming. (See in common with a rain forest Earth’s core, mantle, and thin outer crust—all the warn that without protection, Chapter 16 for more about climate ecosystem. Which part of the Biosphere most of the forests will be gone change.) material above and below the surface that forms (living organisms) ecosystem is most damaged Soil or severely damaged by the end Large-scale loss of tropical rain the planet’s mass. Without its large mass, Earth or threatened? How might this Rock of this century. The preservation forests can also change regional would not have the gravitational force needed to affect the other parts of the Crust keep the atmosphere from escaping into space. The efforts of individuals like National weather patterns in ways that ecosystem and its long-term Geographic Explorer Vitor Becker prevent the forest from returning. geosphere’s upper crust contains nutrients organisms sustainability? Mantle help combat the degradation of When this irreversible tipping need to live, grow, and reproduce (Science Focus 3.1). ecosystems. point is reached, rain forests The crust also includes nonrenewable fossil fuels— coal, oil, and natural gas—and mineral resources. Geosphere (crust, mantle, core) The Atmosphere Held to Earth by gravity, the Mantle June 1975 July 2013 FigurE 3-1 Satellite images of the atmosphere is an envelope of gases surrounding same area show the the planet (Figure 3-4). If Earth were the size of a Core loss of tropical rain basketball, the atmosphere would be about the Atmosphere forest near the Bolivian thickness of a sheet of paper. This thin blanket of (air) city of Santa Cruz de la Sierra. The forest was gases shields the planet from meteors and blocks cleared for farming, most of the sun’s harmful ultraviolet (UV) radiation. cattle grazing, and It also helps regulate Earth’s climates, allowing settlements between June 1975 (left) and surface temperatures to be suitable for life to exist in Hydrosphere July 2013 (right). the troposphere, the lowest layer of the atmosphere. (water) The troposphere is the layer in which weather occurs. It is also the only layer in which terrestrial organisms can survive. Thickest at the Equator, the troposphere extends up to 19 kilometers (12 miles) above sea level. At the Poles, the troposphere

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070-103_ES_SE_37429_U1_C03.indd 68 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 69 1/29/16 4:53 PM FigurE 3-3 Hundreds of macaws make up for the Oxygen 21% FigurE 3-4 lack of sodium in their diet by eating small The Atmosphere On average, the troposphere amounts of salty clay at this avian salt lick Argon 0.9% layer is 78% nitrogen and 21% oxygen. The in Manu National Park, Peru. Sodium is an Carbon dioxide 0.04% essential mineral nutrient. remaining 1% is mostly argon, water vapor, carbon dioxide, and other gases. The amount Other gases 0.06% of water vapor may increase to more than 4% Nitrogen 78% depending on altitude and air temperature.

Other fresh water 1.2% Ocean 96.5% groundwater 30.1%

FigurE 3-5 The Hydrosphere At any given time, Fresh water 2.5% approximately 96.5% of Earth’s water glaciers and ice caps 68.7% molecules exist in the ocean. What percentage of the hydrosphere consists of glaciers and ice caps? (Hint: The answer is not 68.7%.) Other saline water 0.9%

The Hydrosphere Glaciers, lakes, rivers, aquifers, the greenhouse effect, Earth would be too cold to water vapor, clouds, and the ocean are all part of support life as we know it. the hydrosphere (Figure 3-5). The hydrosphere Interactions among the spheres clean Earth’s water includes all of the gaseous, liquid, and solid water on and air. As plants absorb water and water transpires, or near Earth’s surface. The distribution of water is or evaporates from their leaves, pollutants are dominated by the ocean, which contains about 96.5% absorbed. Animals such as clams and mussels filter SCIENCE FocUS 3.1 of Earth’s total supply of water and covers about impurities from bodies of water, and microorganisms 71% of its surface. Less than 3% of Earth’s water is in water and soil can break down many contaminants. available as fresh water, and most of that is frozen in As water evaporates from Earth’s surface into the NUTRIENT CYCLING resulting atoms, ions, and by which organisms obtain most of polar ice caps and glaciers. atmosphere, particles that make the water impure Life on Earth depends on two molecules form the planet’s living their nutrients. The Biosphere If Earth were an apple, the are left behind. processes: the one-way flow of organisms and the nutrients they Macronutrients are nutrients biosphere would be no thicker than the apple’s Forests play an important role in purifying air. energy from the sun and the need to survive. that organisms need in large skin. The biosphere consists of the parts of the Trees can absorb air-polluting gases near the surface. cycling of matter through the Earth does not get significant amounts. They form the bulk of atmosphere, hydrosphere, and geosphere where A single tree can produce enough oxygen for two biosphere. This is in keeping with inputs of matter from space, so the foods you eat. Proteins, fats, life exists. It is the living part of every ecosystem. people to breathe for a year. The same tree might the solar energy and nutrient the fixed supply of nutrients must and carbohydrates are examples of An important goal of environmental science is to absorb about 4.5 kilograms (10 pounds) of pollutants cycling factors of sustainability be recycled to sustain generation macronutrients. Micronutrients— understand the key interactions that occur within this in a year. described in Chapter 1. after generation of organisms. vitamins and minerals—are thin layer of air, water, soil, and organisms, and how checkpoint What are some of the gases that help produce The life-sustaining energy of Carbon, oxygen, nitrogen, nutrients that organisms need in human activities affect the biosphere. the greenhouse effect? nearly every ecosystem originates and phosphorus are examples very small amounts. with sunlight, converted to of elemental nutrients that are Vitamins are considered checkpoint In which layer of the atmosphere do you live? chemical energy by plants and continually recycled through the “organic” compounds because they 3.1 Assessment other producers. As you will living (biosphere) and nonliving contain carbon. Minerals, which do Earth’s Spheres Interact (atmosphere, hydrosphere, not contain carbon, are “inorganic” 1. recall What are Earth’s four major spheres that learn in Lesson 3.3, without the Through a process known as the greenhouse effect, continual input of energy from the geosphere) parts of ecosystems. compounds. Some important support life? Water helps cycle these important mineral nutrients include calcium, solar energy warms the troposphere as it reflects sun, nearly every ecosystem would from Earth’s surface (geosphere) and interacts with 2. Explain What is the greenhouse effect and why is quickly run out of the energy nutrients and is itself an essential zinc, potassium, and iron. it important to life on Earth? nutrient. carbon dioxide (CO2), methane (CH4), water vapor needed for life. 3. generalize What is Earth’s “life-support system”? What makes something a (from the hydrosphere and biosphere), and other As energy flows through CROssCuttINg CONCepts nutrient? A nutrient is any matter Thinking Critically greenhouse gases (atmosphere). These interactions ecosystems, it fuels the building 4. Systems and System Models use one or more that an organism needs to survive Infer How would nutrient cycling be are part of Earth’s life-support system. Without up and breaking down of chemical affected if all of Earth’s producers examples from everyday life to explain how Earth’s compounds (Lesson 3.4). The and function. Feeding is the means died off? four major spheres interact.

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070-103_ES_SE_37429_U1_C03.indd 70 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 71 1/29/16 4:53 PM 3.2 What Are the Major producers such as plants make the food they FigurE 3-7 need from compounds in soil, carbon dioxide in Matter on the Move Arrows in this simplified ecosystem trace Ecosystem Components? the movement of matter through key living (biotic) and nonliving air, and water—using the energy of sunlight. In the (abiotic) components. process known as photosynthesis, producers change CORE IDEAS AND SKIllS radiant energy (sunlight) into chemical energy stored • Describe trophic levels and how they can be primarily in glucose. By harnessing the energy of represented in a conceptual model. Oxygen (O ) light, producers can convert inorganic molecules of 2 • Explain the roles of producers, consumers, and carbon dioxide and water into organic molecules Precipitation decomposers in an ecosystem. such as glucose. Glucose (C6H12O6) is an important • Identify the different ways in which energy and matter building block of many energy-rich carbohydrates are transformed in an ecosystem. that are necessary for life. The chemical equation for • Summarize the processes of photosynthesis and Carbon dioxide (CO ) photosynthesis is: 2 cellular respiration. KEY TERMS carbon dioxide + water + light energy glucose + oxygen 6 CO + 6 H 0 + light energy C H O + 6 O trophic level secondary decomposer 2 2 6 12 6 2 Producer producer consumer detritivore photosynthesis tertiary aerobic consumer consumer respiration FigurE 3-6 primary carnivore anaerobic Ladder of Matter Ecology includes all of these levels of the consumer omnivore respiration organization of matter. Secondary herbivore consumer (fox) Parts of Earth’s air, water, and soil Primary Biosphere where life is found consumer Ecosystems Have Several (rabbit)

Important Components A community of different species Ecology is the branch of biology that focuses on ecosystem interacting with one another and with their nonliving environment how organisms interact with one another and their physical environment (Lesson 1.1). Scientists classify Populations of different species living Producers matter into levels of organization ranging from atoms Community in a particular place and potentially interacting with each other to galaxies. Ecologists study interactions within and among several of these levels—from molecules to A group of individuals of the Water Decomposers the biosphere. See Figure 3-6 for a definition of each population same species living in a particular place level. Soluble mineral nutrients The biosphere and its ecosystems are made up of An individual living entity such as a living (biotic) and nonliving (abiotic) components. Organism bacterium or plant Examples of nonliving components are water, On land, most producers are green plants such feed on phytoplankton. secondary consumers are air, rocks, nutrients, thermal energy (heat), and The fundamental structural as trees and grasses. In freshwater and ocean animals that feed on primary consumers. tertiary (or sunlight. Living components include plants, animals, Cell and functional unit of life ecosystems, algae and aquatic plants growing near higher-order) consumers feed on both primary and microbes, and all other organisms. Figure 3-7 is a shorelines are the major producers. In open water, secondary consumers. simplified model of some of the living and non-living A chemical combination of two or more atoms of the same or the dominant producers are phytoplankton—mostly Among the secondary and tertiary groups are components of a terrestrial ecosystem. Molecule different elements microscopic organisms that float or drift in the water. carnivores and omnivores. Carnivores feed mostly Ecologists assign each organism in an ecosystem to The other organisms in an ecosystem that are not on other animals. Some carnivores, including a feeding level called a trophic level. An organism’s The smallest unit of a chemical Atom element that exhibits its producers are consumers. Consumers are organisms spiders, lions, and most small fishes, are secondary trophic level depends on (a) whether it makes food chemical properties that cannot produce their own food. They get the consumers. Others, such as tigers, hawks, and killer or finds food, and (b) if it finds food, what its feeding food and energy they need by feeding on producers whales (orcas), are tertiary consumers. behavior is. Organisms are classified as producers or or other consumers, or on the wastes and remains of Omnivores, such as pigs, rats, and humans, eat consumers by whether they make (produce) or find producers and consumers. both plants and animals. Like carnivores, omnivores (consume) food. primary consumers, or herbivores, are may be secondary or tertiary consumers. organisms that eat mostly green plants or algae. Examples of herbivores are caterpillars, giraffes, and zooplankton, which are tiny sea animals that

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ScEYEnce Studios Miller/Spoolman, ES 15e FIG_13.07 1st Proof 2nd Proof 3rd Proof Final FigurE 3-8 ON ASSigNMENT National geographic photographer Frans Lanting snapped this image of deforestation while flying above the edge of a lush rain forest in Brazil’s iguacu National Park. The stark agricultural landscape reveals the park’s boundary—and the loss of biodiversity when crops replace trees.

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070-103_ES_SE_37429_U1_C03.indd 74 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 75 1/29/16 4:53 PM Decomposers are consumers that get their In natural ecosystems, decomposers and nutrients by breaking down (decomposing) nonliving detritivores eliminate the build up of plant litter, organic matter such as leaf litter, fallen trees, and animal wastes, and dead plants and animals. In doing dead animals. In the process of obtaining their own so, they are the key to nutrient cycling. For example, food, decomposers release nutrients from the wastes decomposers and detritivores can transform a fallen or remains of plants and animals. The process of tree into wood particles and, finally, simple inorganic decomposition returns nutrients to soil and water, molecules that producers absorb as nutrients (Figure making them available to the ecosystem. Most 3-9). In this way, many of the nutrients that make life decomposers are bacteria and fungi. Detritivores, or possible are continually recycled. detritus feeders, get their nourishment by consuming checkpoint What does an organism’s trophic level indicate detritus, or freshly dead organisms, before they about that organism? are fully decomposed. Detritus feeders include earthworms, some insects, hyenas, and vultures.

FigurE 3-9 Detritivores and Decomposers Various detritivores and decomposers (mostly fungi and bacteria) “feed on” or digest parts of a log. They eventually convert its complex organic chemicals into simpler inorganic nutrients that can be used by producers. Figure 3-10 This color-enhanced photo reveals a species of bacteria, shown in red, that is Detritivores Decomposers being studied for its potential to help clean up soil and groundwater contaminated with chlorinated solvents, a common pollutant.

ENGINEERING Focus 3.2

Long-horned Bark beetles beetle larvae bore burrow passages Carpenter ants NatuRE’s ClEaNup CREw to break down pollutants in from one species of bacteria to under bark. into wood. excavate wood The word microbe, or oil spills and toxic waste leaks. another—usually a local species Termites feed to make Dry rot fungi Bioremediation is the use of that lives naturally in the sort of on wood. microorganism, is a catchall galleries. feed on wood. term for thousands of species microbes or other decomposers to environmental conditions that of bacteria, protozoa, fungi, and clean up polluted sites. are found at the cleanup site. As floating phytoplankton. Microbes But using microbes for you can imagine, the resulting environmental cleanup doesn’t combination of traits—an appetite Wood is reduced play key roles as decomposers always work as planned. Toxins can for oil or other pollutant at a to a powdery substance. throughout the entire biosphere. Bacteria and fungi in the soil be hard to digest. Some microbes contamination site, and the ability and oceans decompose organic have the genes to survive in an to flourish under the natural wastes into inorganic nutrients environment, but not to clean it, conditions found there—makes for such as nitrogen and phosphorus. while others have the genes to much more resilient bacteria. Time progression Fungi in soil feed on what clean it, but wouldn’t be able to remains, converting it into The nutrients are then taken up survive in the environment. simple inorganic molecules. by plants that are then eaten Thinking Critically by consumers. Within your own Environmental engineers are solving this problem by creating Evaluate What are some possible intestinal ecosystem, trillions of risks of introducing genetically bacteria are busily breaking down custom-made bacteria with the engineered bacteria into the the food you eat. genes needed for a specific job. environment? Scientists and engineers have Bioengineers have learned how learned how to use microbes to transfer the desired genes

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070-103_ES_SE_37429_U1_C03.indd 76 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 77 2/1/16 3:17 PM FigurE 3 -11 3.3 What Happens to Energy most of it flowing into the environment as low- Component interactions The main Solar quality thermal energy (heat). Thus, there is less high- components of an ecosystem are energy, Chemical nutrients energy in an Ecosystem? (carbon dioxide, quality energy left to support large numbers of top matter, and organisms. Nutrient cycling and Heat oxygen, nitrogen, the flow of energy—first from the sun, then predators such as tigers or hawks (Figure 3-12). minerals) CORE IDEAS AND SKIllS through organisms and into the environment as Food webs offer another way to describe the heat—link these components. • Identify the role of food chains and food webs in an flow of energy through ecosystems. A food web is ecosystem. a complex network of interconnected food chains. Heat Heat • Describe the flow of energy through an ecosystem. Food webs are useful in studies at the ecosystem • Explain the difference between gross primary level. For example, scientists studying the effect productivity and net primary productivity. of decreasing killer whale populations on marine

Decomposers Producers KEY TERMS ecosystem health may refer to food webs similar (bacteria, fungi) (plants) food chain gross primary productivity (GPP) to the one illustrated in Figure 3-15. Food chains food web net primary productivity (NPP) and food webs show how producers, consumers, and decomposers are connected to one another as energy flows through trophic levels in an ecosystem. Food Chains and Food Webs checkpoint What is the difference between a food chain Consumers Food chains and food webs describe how energy and a food web? (plant eaters, Heat meat eaters) Heat flows through ecosystems. A sequence of organisms that serves as a source of nutrients or energy for the Primary Productivity next level of organisms is called a food chain. Figure 3-13 illustrates a simplified food chain. Scientists measure the rates at which ecosystems Cellular Respiration Anaerobic respiration also occurs temporarily in Organisms at each trophic level obtain high-quality produce chemical energy to compare ecosystems oxygen-starved muscle cells, a by-product of which and understand how they interact. gross primary Organisms use the chemical energy stored in glucose chemical energy from their food. However, about is lactic acid (C H O ). All organisms—including productivity (gpp) is the rate at which an and other organic compounds to fuel their life 3 6 3 90% of the chemical energy is lost at each link in producers—get their energy from aerobic or ecosystem’s producers convert radiant energy into processes. In most cells, this energy is released by the food chain, as required by the second law of anaerobic respiration. Only producers, however, carry chemical energy. This energy is stored in compounds aerobic respiration, which uses oxygen and glucose thermodynamics (Lesson 2.2). So where does the out photosynthesis. in their bodies. To stay alive, grow, and reproduce, to produce energy. Carbon dioxide and water are the energy go? As organisms live and grow and their cells To summarize, ecosystems and the biosphere are producers must use some of their stored chemical by-products of this reaction. The chemical equation respire, the chemical energy obtained through food sustained by the one-way energy flow from the sun energy for cellular respiration. for aerobic respiration is: is converted to other forms of energy. When energy through these systems and the nutrient cycling of key transforms from one form to another in a food chain, Net primary productivity (Npp) is the rate at glucose + oxygen carbon dioxide + water + energy materials within them (Figure 3-11). there is an automatic loss of energy “quality,” with which producers use photosynthesis to produce and C H O + 6 O 6 CO + 6 H O+ energy 6 12 6 2 2 2 checkpoint What is the difference between aerobic and Although the detailed steps differ, the net anaerobic respiration? chemical change for aerobic respiration is the opposite of that for photosynthesis. As cells respire, FigurE 3-12 3.2 Assessment Only a small fraction of energy produced at the reaction also produces some thermal energy, the lowest trophic level is available to top which is eventually lost to the environment as heat. predators such as this black-collared hawk. 1. Contrast How are photosynthesis and cellular Decomposers such as yeast and some bacteria get respiration different? the energy they need by breaking down glucose and 2. infer Could an ecosystem function without other organic compounds in the absence of oxygen. decomposers? Why or why not? This form of cellular respiration is called anaerobic sCIeNCe AND eNgINeeRINg pRACtICes respiration, or fermentation. Instead of carbon 3. use Models How would you revise Figure 3-7 to dioxide and water, the by-products of this process account for tertiary consumers, photosynthesis, are compounds such as methane gas (CH4 , the main aerobic respiration, and anaerobic respiration?

component of natural gas), ethyl alcohol (C2H6O), CROssCuttINg CONCepts

acetic acid (C2H4O2 , the key component of vinegar), 4. Energy and Matter Explain why a natural

and hydrogen sulfide (H2S, a highly poisonous gas ecosystem is both an open system and a closed that smells like rotten eggs). system.

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070-103_ES_SE_37429_U1_C03.indd 78 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 79 1/29/16 4:53 PM First Trophic Second Trophic Third Trophic Fourth Trophic FigurE 3-15 Level Level Level Level Food Web A simplified Humans Producers Primary Secondary Tertiary food web shows some of (plants) consumers consumers consumers the feeding relationships (herbivores) (carnivores) (top carnivores) among marine organisms in Blue whale Sperm whale the Southern Hemisphere. Heat Heat Heat Heat The shaded middle area is a food chain within the more complex food web. Many Elephant more species, including an Solar seal energy array of decomposer and detritus feeder organisms, Crabeater are not shown in this Killer seal whale Heat model. FigurE 3-13 Food Chain Notice Heat Heat the energy flow in this model. How does it Leopard show that high-quality seal energy is not recycled? Decomposers and detritus feeders Adelie Emperor penguin penguin Usable energy available FigurE 3-14 at each trophic level Heat Energy Pyramid (in kilocalories) Tertiary Energy pyramids consumers 10 Squid model the general loss (human) Petrel of available energy Heat at each trophic level. Energy pyramids are Fish not drawn to scale. Secondary consumers Similar diagrams, called 100 (perch) Heat biomass pyramids, Decomposers Heat show the decrease in Carnivorous dry weight of organic Primary zozooplanktonoplankton matter at each level. consumers 1,000 (zooplankton) Heat Krill Herbivorous zooplankton 10,000 Producers (phytoplankton) Phytoplankton

store chemical energy, minus the rate at which they because of the enormous volume of the ocean and its 3.3 Assessment use some of this stored chemical energy through huge numbers of phytoplankton and other producers. sCIeNCe AND eNgINeeRINg pRACtICes cellular respiration (Figure 3-14). In other words, NPP Only the plant matter represented by NPP is 1. identify Main ideas What is the ecological role 4. Developing and using Models Create a of food chains and food webs? is the difference between gross primary productivity available as nutrients for consumers. Thus, the simplified model of a food chain in your region. and cellular respiration. NPP is a measure of the rate planet’s NPP ultimately limits the number of consumers 2. Summarize What is the difference between include the names of the organisms and their at which producers make chemical energy potentially (including humans) that can survive. This is one of gross primary productivity (gPP) and net primary relationship to each other. indicate the flow available to the consumers in an ecosystem. nature’s important lessons. When the most highly productivity (NPP)? of energy, starting with the sun and including Ecosystems vary in their NPP. For example, tropical productive ecosystems suffer destruction from 3. Synthesize The plants in a red-tailed hawk’s food producers, consumers, and decomposers. rain forests have a high NPP and collectively are human activities, Earth’s total productivity is chain produce 3 million kcal of chemical energy per sCIeNCe AND eNgINeeRINg pRACtICes large contributors to Earth’s overall NPP. They have reduced—and so is the total number of consumers day. How much energy is available to the hawk’s 5. Constructing Explanations Explain how a great abundance and variety of plants to support the planet can support. trophic level, assuming 90% loss at each level? diagrams can be useful for studying smaller-scale a large biomass of consumers. By contrast, the open (Hint: refer to Figure 3-13.) mechanisms within the larger ecosystem. Discuss checkpoint What happens to energy as it flows through the limitations of such models. ocean has a low NPP but is more productive annually food chains and food webs? than any other ecosystem or life zone. This happens

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070-103_ES_SE_37429_U1_C03.indd 80 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 81 1/29/16 4:53 PM The Hydrologic Cycle FigurE 3-16 3.4 What Happens to Matter Hydrologic Cycle This illustration shows a simplified model of the hydrologic, or water, cycle. Water circulates in various physical forms within in an Ecosystem? Water (H2O) is essential to life on Earth. The hydrologic cycle, also called the water cycle, the atmosphere, geosphere, hydrosphere, and biosphere. The red arrows and boxes identify major effects of human activities on this cycle. CORE IDEAS AND SKIllS collects, purifies, and distributes Earth’s fixed supply • Describe the hydrologic cycle. of water (Figure 3-16). The water cycle facilitates all of the important nutrient cycles discussed later in this • Describe nutrient cycles within and among ecosystems and the biosphere. chapter. Condensation Condensation The sun provides the energy needed to power the • Explain how human activities impact nutrient cycles in Ice and ecosystems. water cycle. In the water cycle, incoming solar energy snow causes evaporation. Evaporation is the conversion KEY TERMS of liquid water to water vapor. Most water vapor Transpiration nutrient cycle groundwater nitrogen cycle rises in the atmosphere, where it condenses into from plants hydrologic cycle aquifer phosphorus cycle droplets in clouds. Gravity then draws the water Precipitation surface runoff carbon cycle to land Evaporation of surface water back to Earth’s surface as precipitation, such as Evaporation rain, snow, or sleet. Above land about 90% of the from ocean Nutrients Cycle Within and water vapor in the atmosphere evaporated from Runoff Among Ecosystems soil and plants. Evaporation from plant surfaces is called transpiration. Plants draw enormous amounts Lakes and The elements and compounds that make up nutrients reservoirs Precipitation move continually through air, water, soil, rock, of water from the ground through their roots. to ocean and living organisms within ecosystems. Within Transpiration is the process by which plants use Runoff evaporation to release excess water through tiny Increased runoff on the biosphere, this movement of matter occurs in land covered with crops, pores in their leaves. buildings, and pavement nutrient cycles, or biogeochemical cycles (life-earth- Infiltration chemical cycles). Nutrient cycles are driven directly When precipitation returns to Earth’s surface, it and percolation Increased runoff takes various paths. Most precipitation falling on land into aquifer from cutting or indirectly by energy from the sun and by Earth’s Runoff forests and gravity. These cycles include the hydrologic (water), ecosystems becomes surface runoff. Surface runoff filling wetlands carbon, nitrogen, and phosphorus cycles. They are flows over land surfaces into streams, rivers, lakes, important parts of Earth’s natural capital. Yet, human wetlands, and the ocean, where it can evaporate and repeat the cycle. Groundwater Overpumping activities are disrupting these cycles. in aquifers of aquifers Water pollution As a nutrient moves through a biogeochemical Some precipitation seeps into the soil. This water Runoff cycle, it may accumulate in a certain stage of the may evaporate back into the atmosphere or be cycle and remain there for varying periods. Such consumed by plants and other organisms. Water that temporary reservoirs include the atmosphere, the seeps deeper through soil is known as groundwater. Ocean ocean and other bodies of water, underground Groundwater collects in aquifers, which are underground layers of sand, gravel, and water-bearing deposits, and living organisms. Natural process Throughout your study of environmental science, rock. Natural reservoir you may want to refer to the diagrams on these Water easily dissolves many compounds, which Human impacts pages again and again because they relate to many means it can be polluted easily. Throughout the key lessons of the book. For example, when studying hydrologic cycle, several natural processes purify Natural pathway forms of pollution or overuse of natural resources, water by drawing out pollutants. For example, Pathway affected by human activities these cycles will help you understand the impact when water evaporates, dissolved solids, including human actions can have on Earth’s life support pollutants, are left behind. The hydrologic cycle Only about 0.024% of Earth’s vast water supply is Human Impacts Humans alter the water cycle in system and possible solutions for maintaining can be viewed as a natural cycle of water quality available to humans and other species as liquid fresh three primary ways. (See the red arrows and boxes in sustainability on Earth. renewal—an important and free ecosystem service. Without the hydrologic cycle’s purification processes, water. This small fraction is further reduced when Figure 3-16.) checkpoint Why do you think it is important to humans and other species would rapidly run out of human activities pollute freshwater sources. Fresh First, people drain and fill wetlands for farming understand biogeochemical cycles? drinkable water. water is found in accessible groundwater deposits and urban development. Left undisturbed, wetlands and in surface water from lakes, rivers, and streams. provide the ecosystem service of flood control. Some groundwater deposits are too deep to extract Wetlands act like sponges to absorb and hold affordably. The rest of the planet’s water is too salty overflows of water from drenching rains or rapidly to drink or is permanently frozen in glaciers. melting snow.

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wATER the temperature of most other Water expands when it Without water, Earth would be liquids. This property of water freezes. Ice floats on water a lifeless planet. Water’s unique helps organisms regulate body because it has a lower density properties make it one of nature’s temperature and plays a critical (mass per unit of volume) than its most extraordinary compounds. role in moderating Earth’s climate. liquid form. Otherwise, lakes and Here are a few of the reasons why Liquid water dissolves more streams in cold climates would water is so wondrous. substances than any other liquid. freeze solid, killing virtually all Water exists as a liquid over For this reason, water is often of the aquatic life. This special a wide range of temperatures. called the “universal solvent.” In property fractures rocks in a At first glance, this may not seem nutrient cycling, water is like the phenomenon called ice wedging. important. But what if liquid water vehicle in which nutrients travel. Thus, water plays a major role in had a narrower temperature range Water carries dissolved nutrients shaping landscapes and between freezing and boiling like into the tissues of living organisms forming soil. so many other liquids? The ocean and flushes waste products from would have frozen solid or boiled those tissues. (More than half of Thinking Critically away long ago. your body mass is water.) It helps remove and dilute the water- Infer The expansion of water when it Liquid water has a high heat freezes plays a major role in shaping capacity. In other words, water soluble wastes of civilization. landscapes and forming soil. Which can store a large amount of Unfortunately, this property other property described above also makes water susceptible to also plays a major role in altering thermal energy. It takes a lot more landscapes? energy to raise the temperature pollution. of water than it does to raise

Second, people withdraw fresh water from rivers, consumers. In the carbon cycle (Figure 3-18), lakes, and aquifers, often at rates faster than natural different compounds of carbon circulate through the processes can replace it. As a result, some aquifers biosphere, atmosphere, and parts of the geosphere are being depleted and several rivers no longer flow and hydrosphere. to the ocean. A key component of the carbon cycle is carbon

Third, people clear vegetation from land for dioxide (CO2) gas. Carbon dioxide makes up only agriculture, mining, road building, and other about 0.04% of the volume of the atmosphere and is activities, and then cover much of the land with also dissolved in water. The amount of carbon dioxide buildings, concrete, and asphalt. This increases runoff (along with water vapor) has a big effect on global and reduces infiltration that normally recharges temperatures because of the greenhouse effect groundwater supplies. (Lesson 3.1). On land, photosynthesis by producers moves checkpoint How does energy from the sun drive the hydrologic cycle? carbon from the atmosphere to the biosphere. In marine environments, producers remove carbon from The Carbon Cycle water. Meanwhile, the cells of oxygen-consuming producers, consumers, and decomposers (both Carbon is the basic building block of the terrestrial and aquatic) carry out aerobic respiration. FigurE 3-17 carbohydrates, fats, proteins, DNA, and all other As you learned in Lesson 3.3, the by-product of ON ASSigNMENT National geographic organic compounds required for life. Carbon photographer Peter McBride documents aerobic respiration is water and CO2. Together, the this canoeist’s struggle through a shallow is found in every cell of your body. It is part of processes of photosynthesis and aerobic respiration pool of garbage and muddy froth at the the carbohydrate molecules produced through circulate carbon through the biosphere. end of the Colorado river, just inside photosynthesis and eaten or decomposed by Mexico.

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070-103_ES_SE_37429_U1_C03.indd 84 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 85 1/29/16 4:53 PM FigurE 3-18 FigurE 3-19 Carbon Cycle This simplified model shows the circulation of Nitrogen Cycle Various chemical forms of nitrogen circulate in various chemical forms of carbon in the global carbon cycle. this simplified model of the nitrogen cycle. red arrows indicate the major harmful human impacts. (Yellow box sizes do not represent relative reservoir sizes.) Denitrification by bacteria Carbon dioxide Nitrogen in atmosphere in atmosphere Respiration Nitrogen fixation by bacteria Photosynthesis

Nitrogen Electrical storms in animals Animals Nitrogen oxides (consumers) (consumers) from burning fuel Burning and using inorganic fossil fuels fertilizers Diffusion Forest fires Commercial nitrogen Nitrogen fertilizer in plants Plants (producers) Deforestation (producers)

Decomposition Transportation Respiration Nitrates from fertilizer Carbon Uptake by plants in plants runoff and decomposition (producers) Carbon dioxide Carbon dissolved in ocean in animals (consumers) Nitrate Decomposition in soil Marine food webs Carbon Producers, consumers, in fossil fuels decomposers Nitrogen Nitrogen Nitrification loss to deep in ocean by bacteria ocean sediments sediments Ammonia Carbon in soil in limestone or Compaction Process dolomite sediments Reservoir

Process Pathway affected by humans Reservoir Natural pathway

Pathway affected by humans Natural pathway The Nitrogen Cycle nucleic acids, and vitamins necessary for their own survival and that of other organisms. Animals that eat Nitrogen gas (N ) makes up 78% of the volume of 2 plants absorb these nitrogen-containing compounds, the atmosphere. Nitrogen is a crucial component On land, decomposers release some of the Human Impacts Humans are altering the carbon as do detritivores and decomposers. of proteins, many vitamins, and DNA. Despite its carbon stored in the bodies of dead organisms back cycle mostly by adding large amounts of carbon Organisms return nitrogen-rich organic abundance and importance to life, nitrogen cannot into the air as CO . Carbon dioxide can remain in dioxide to the atmosphere. (See the red arrows and compounds to the environment in their wastes 2 be absorbed and used directly as a nutrient by plants the atmosphere for 100 years or longer. In water, boxes in Figure 3-18.) In the past few hundred years, and cast-off particles of matter such as leaves, or other organisms. It becomes usable by producers decomposers release carbon that can be stored as humans have extracted and burned huge quantities skin, or hair. When organisms die, their bodies only in the form of compounds such as ammonia insoluble minerals in bottom sediment for much of fossil fuels that took millions of years to form, + are decomposed or eaten by detritus feeders. In (NH ) and ammonium ions (NH ). longer periods. In fact, marine sediments are Earth’s releasing tremendous quantities of CO into the 3 4 both instances, specialized bacteria break down 2 These compounds are created within the nitrogen largest store of carbon. atmosphere. Humans also alter the cycle by clearing the remains into simpler chemicals such as nitrate cycle (Figure 3-19) by reactions involving either Over millions of years, the carbon in deeply buried carbon-absorbing vegetation from forests, especially ions (NO ), ammonia (NH ) and ammonium ions lightning or specialized bacteria found in topsoil and 3 3 marine deposits of dead plant matter and algae were tropical forests, faster than it can grow back (Case (NH +). Bacteria then convert such chemicals to N aquatic ecosystems. Other bacteria convert most 4 2 converted into carbon-containing fossil fuels. The Study). These alterations contribute to environmental + gas, which returns to the atmosphere to begin the of the NH3 and NH4 in the topsoil to nitrate ions high pressure from the weight of overlying sediments problems that affect the atmosphere and ocean. – nitrogen cycle again. (NO ), which the roots of plants take up. Plants use and heat released during the decomposition of dead 3 checkpoint Why is carbon essential to your survival? these forms of nitrogen to produce the proteins, matter formed coal, oil, and natural gas (fossil fuels).

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070-103_ES_SE_37429_U1_C03.indd 86 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 87 1/29/16 4:53 PM Human Impacts Human activities impact the double again by 2050, which would seriously alter the Human Impacts Human activities, including the streams, lakes, and oceans. Phosphates stimulate nitrogen cycle in several ways. (See the red arrows nitrogen cycle. mining of large amounts of phosphate to make the growth of producers such as algae. Similar to and boxes in Figure 3-19.) Nitric oxide (NO) is added fertilizer, disrupt the phosphorus cycle. (See the red nitrogen-rich runoff, phosphate-rich runoff from checkpoint How can the release of excess nitrates into to the atmosphere as a product of combustion bodies of water affect aquatic organisms? arrows in Figure 3-20.) By clearing tropical forests, the land often causes huge increases in algae when humans burn gasoline and other fuels. In humans expose the topsoil to greater erosion, which populations. As the algae die and decompose, oxygen the atmosphere, NO can be converted to nitrogen The Phosphorus Cycle reduces phosphate levels in the soil. in the water is depleted, wiping out populations of dioxide gas (NO2) and nitric acid vapor (HNO3), Phosphate fertilizer is then added to make up aquatic organisms. which return to Earth’s surface as acid rain. Acid rain Phosphorus (P) is an element that is essential for for the lost phosphate. Eroded topsoil and fertilizer living things. It is contained in ATP, a compound that checkpoint How is the phosphorus cycle different from damages stone buildings and statues. It can also kill washed from fertilized crop fields, lawns, and golf the water, carbon, and nitrogen cycles? forests and other plant ecosystems, and wipe out life provides energy for life processes. It is necessary for courses carry large quantities of phosphate ions into in ponds and lakes. the production of DNA and cell membranes, and is Humans remove nitrogen (N ) from the important for the formation of bones and teeth. 2 The cyclic movement of phosphorus through FigurE 3-20 atmosphere to make ammonia (NH3) and ammonium Phosphorus Cycle Different chemical forms of phosphorus + water, Earth’s crust, and living organisms is called (mostly phosphates) circulate among land, water, and organisms ions (NH4 ) for fertilizers. In addition, humans alter the nitrogen cycle in aquatic ecosystems by adding the phosphorus cycle (Figure 3-20). Most of the in this simplified model of the phosphorus cycle. (Yellow box − sizes do not represent relative reservoir sizes.) excess nitrates (NO ). These nitrates contaminate phosphorus compounds contain phosphate ions 3 (PO 3 −), which serve as an important plant nutrient. bodies of water through agricultural runoff of 4 fertilizers, animal manure, and discharges from As water runs over exposed rocks, it slowly municipal sewage treatment systems. This can cause erodes inorganic compounds that contain phosphate excessive growth of algae that deplete oxygen levels ions. Water carries these ions into the soil, where plants and other producers absorb them. Phosphate and cause stress or death of aquatic organisms. Phosphates Phosphates compounds are then transferred through food webs in sewage According to the 2005 Millennium Ecosystem in fertilizer Plate Assessment, since 1950, human activities have more from producers to consumers. Unlike water, carbon, tectonics and nitrogen, phosphorus does not cycle through the Phosphates than doubled the annual release of nitrogen from the in mining waste Runoff Runoff atmosphere. land into the rest of the environment. Most of this Sea comes from the increased use of inorganic fertilizers The phosphorus cycle is slow compared to the birds to grow crops. The amount released is projected to water, carbon, and nitrogen cycles. As phosphate Runoff is eroded from exposed rocks, much of it is carried Phosphate in rock in rivers and streams to the ocean. When it reaches Erosion (fossil bones, CONSIDER THIS the ocean, phosphate can be deposited as marine guano) Ocean food webs sediments and remain trapped for millions of years. Animals Nutrient cycles connect past, present, Over time, geological processes uplift and expose (consumers) Phosphate Phosphate and future forms of life. dissolved in in shallow some of these seafloor deposits. The exposed rocks water ocean sediments Some of the carbon atoms in your skin may are then eroded, freeing up the phosphorus to re- Phosphate once have been part of an oak leaf, a dinosaur’s in deep ocean enter the cycle. Plants sediments skin, or a layer of limestone rock deep in (producers) Most soils contain little phosphate, which limits the ocean. Your great-grandmother, George Washington, or a hunter-gatherer who lived plant growth on land. For this reason, people often 25,000 years ago may have breathed some of fertilize soil by adding phosphorus (as phosphate the nitrogen molecules you just inhaled. The compounds mined from the ground). Under natural Bacteria hydrogen and oxygen atoms that formed the conditions, low levels of phosphorus also limit the Process water you drank today may have flowed in the growth of producer populations in many freshwater Reservoir Nile River in Egypt thousands of years ago or environments. Phosphate compounds are only floated in a cloud over the Pacific ocean only slightly soluble in water, so they release fewer Pathway affected by humans two months ago. phosphate ions to aquatic producers that need them Natural pathway as nutrients.

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070-103_ES_SE_37429_U1_C03.indd 88 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 89 1/29/16 4:53 PM 3.4 Assessment counts, observing feeding behaviors, and using GPS to track animals’ movements. In this lesson 1. identify Main ideas What is the role of the you will read about the pioneering field research hydrologic cycle in relation to the carbon, nitrogen, of one scientist, National Geographic Explorer and phosphorus cycles? Thomas E. Lovejoy. Much of what people know 2. Summarize Describe at least one way humans about ecosystems comes from data obtained impact each of the following cycles: hydrologic, through field work. carbon, nitrogen, and phosphorus. Scientists who study tropical rain forests, for sCIeNCe AND eNgINeeRINg pRACtICes example, use a variety of methods to study those 3. using Mathematics There are about 11,200,000 ecosystems. Most animals in a tropical forest live in billion metric tons of O in the atmosphere. Based 2 the canopy, which can be as high as 28 meters (92 on an estimated photosynthesis rate of 600 billion feet) above the ground. Scientists often use ropes metric tons per year, how many years might it have and pulleys to access a canopy (Figure 3-21). They taken to reach current O levels? (Note: Assume 2 may also install rope walkways, spiral staircases, for this exercise that the rate of O production is 2 and temporary platforms. Some long-term scientific constant even though it has changed over time.) projects have built construction cranes that tower sCIeNCe AND eNgINeeRINg pRACtICes over the surrounding trees. These “canopy cranes” 4. Developing Models Create a simplified model to illustrate the role of photosynthesis and cellular can bring researchers and heavy equipment to many respiration in the cycling of carbon. include how different points within the canopy. All of these carbon cycles through the biosphere, atmosphere, methods help researchers identify and observe the hydrosphere, and geosphere. rich diversity of species living or feeding in treetop CROssCuttINg CONCepts habitats. 5. Energy and Matter How is matter conserved in Ecologists may carry out controlled experiments in the nutrient cycles? the field by isolating and changing a variable within a defined area. They then compare the results with unchanged areas nearby. You learned about a classic 3.5 How Do Scientists Study example of this in the Case Study in Chapter 2. Advances in technology allow ecologists to obtain Ecosystems? data in new ways. Satellites and aircraft equipped with sophisticated cameras can scan and collect CORE IDEAS AND SKIllS data about Earth’s surface. Scientists use geographic • Compare and contrast the advantages and information system (GIS) software to capture, disadvantages between field research and laboratory store, analyze, and display this data. For example, a research. GIS can convert digital satellite images into global, • Explain why mathematical models are an important regional, and local maps. The maps can show tool for studying natural systems. variations in vegetation, gross primary productivity, • Describe how a better scientific understanding of air pollution emissions, and other variables. More planetary boundaries can help measure the health of ecosystems. recently, scientists have used drones to photograph, document, and monitor rates of deforestation. KEY TERMS Some researchers attach small radio transmitters Holocene Anthropocene to animals and use global positioning systems (GPS) to track where and how far the animals travel. Ecologists Study Ecosystems Directly This technology is an important tool for studying endangered species, which you will learn about in FigurE 3-21 Scientists such as ecologists use several approaches Chapter 7. National geographic Explorer and tropical to increasing the scientific understanding of ecologist greg goldsmith pauses to take ecosystems. Field research involves going into a checkpoint What are some of the methods ecologists use notes a mere 30 meters (98 feet) above in field research? the ground. Some of greg’s fieldwork natural setting to study one or more features of an involves hanging out with wildlife in the ecosystem. Ecologists have numerous methods of upper canopy of this montane cloud forest field research, including taking water or soil samples, in Costa rica. identifying the species in an area, doing population

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070-103_ES_SE_37429_U1_C03.indd 90 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 91 1/29/16 4:53 PM Ecologists Study Ecosystems Indirectly Scientific knowledge advances when multiple FIGURE 3-22 Nitrogen and Phosphorus Cycles Planetary Boundaries The table Disruption of the nitrogen and phosphorus cycles caused by lines of evidence support the same explanation, so greatly increased use of fertilizers Most ecologists supplement their field research describes planetary boundaries for nine ecologists often use a combination of indirect and by conducting research in laboratories. In a major systems that help sustain life. A direct observation. team of scientists estimated that human Climate Change lab, scientists can set up, observe, and make activities may have exceeded the Altering the carbon cycle, mostly by overloading it with CO2 Ecologists also use mathematical modeling. produced by burning fossil fuels measurements of model ecosystems and populations. boundary limits of four of these Mathematical models can simulate large and complex systems (the first four, shown They can create simplified systems in culture tubes, Biodiversity Loss systems with many variables and large data sets. in red). bottles, aquariums, and greenhouses, and in indoor Replacing biologically diverse forests and grasslands with The models usually require so many variables and so simplified fields of single crops and outdoor chambers. much data that they can only be run on a high-speed By isolating biological systems, scientists can Land Use supercomputer. Whole systems such as lakes, oceans, Land system change from agriculture and urban development control variables such as temperature, light, CO , 2 forests, and Earth’s climate cannot be observed in and humidity. Scientists must consider how well Freshwater Use their entirety or modeled physically. The scope of Global consumption of water per year their observations and measurements in laboratory these systems is too large, and the timescales may conditions reflect what actually takes place in the Ocean Acidification be too long, for direct study. Mathematical modeling, more complex and often changing conditions found Acidification of the ocean caused by increased carbonate however, is ideally suited to these large-scale natural concentration in nature. Although they provide only part of the systems. picture, controlled experiments (in the field or a lab) Ozone Depletion Stratospheric ozone concentration offer the best means by which to identify cause-and- checkpoint What are some of the methods ecologists use effect relationships. in laboratory research? Atmospheric Aerosols Atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms)

NATIONAl GEOGRAPHIC ExPlORERS AT WORK Chemical Pollution Tropical and Conservation Biologist Levels of toxic heavy metals and endocrine disruptors thomas e. Lovejoy Introduction of novel entities (e.g., organic pollutants, radioactive wastes, nanomaterials, and micro-plastics) forests of Brazil since 1965. He pollution—are a matter of public helped start the world’s largest interest today largely through and longest-running study of Lovejoy's efforts at raising public habitat fragmentation, the awareness. SCIENCE Focus 3.4 Biological Dynamics of Forest Lovejoy founded the popular Fragments Project (BDFFP). Since and widely-acclaimed public TESTINg PlaNETary resources and have become the trigger abrupt and long-lasting 1979, the project has measured television series Nature. He has BouNdarIES dominant cause of changes to environmental changes that will the impacts of fragmentation also written numerous articles For most of the past 10,000 the planet’s major systems that degrade the planet’s ability to across a 1,000 square-kilometer and books on issues related to years, humans have lived in an era sustain life. support life. They argue that (386 square-mile) area of the the conservation of biodiversity. called the Holocene—a period In 2015, an international group there is an urgent need for more central Amazon. In addition to teaching of relatively stable climate and of 28 scientists, led by Will research to better define the Meet conservation biologist A goal of the BDFFP is to environmental science and policy other environmental conditions. Steffen and Johan Rockström of boundary limits of these planetary and National Geographic define the minimum amount at George Mason University, he This general stability has allowed the Stockholm Resilience Centre, systems, which are still not exact. Explorer Thomas E. Lovejoy, the of land area necessary for has held several important posts, humans to develop agriculture identified the boundaries, or They also say we need to learn person who coined the term sustaining biodiversity in a including director of the World and expand the human population ecological tipping points, of nine more about what exceeding the biological diversity. For decades, tropical forest. As forests Wildlife Fund’s conservation around the world. major planetary systems that play boundaries will do to the health of Dr. Lovejoy has played a major become increasingly fragmented, program, president of the Society Although most geologists a key role in supporting life. (Recall humans and other species. role in educating people about a better understanding of for Conservation Biology, and argue that we are still living in that an ecological tipping point is If this is the Anthropocene, how the need to protect biodiversity. how fragmentation affects executive director of the UN the Holocene, a growing number like a system’s “point of no return,” will it end for humans and other His conclusions about biodiversity is more important Environment Programme (UNEP). of other scientists think we are resulting in severe degradation species? What will Earth’s next era biodiversity are supported by than ever before. In 2012, he was awarded the Blue living in a new era, which they call or collapse.) The team’s research look like? data he and others have collected Threats to tropical forest Planet Prize for his efforts to the Anthropocene. According to indicates that, apparently, we have over many years of field research. ecosystems—such as understand and sustain Earth’s their argument, the Anthropocene exceeded four of these boundaries Lovejoy has been carrying out Thinking Critically deforestation, poaching, and biodiversity. began around 1750 with the (Figure 3-22). field research in the Amazon According to the Stockholm Infer Which boundaries are most Industrial Revolution. Since that affected by urban development? time, people have been consuming group, if humans exceed too Which ones are most affected by a much greater share of Earth’s many boundaries, we could agriculture?

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070-103_ES_SE_37429_U1_C03.indd 92 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 93 2/1/16 3:04 PM 3.5 Assessment CHApTER 3 SUMMARY 1. Compare and Contrast Compare and contrast 3. Draw Conclusions How can a better scientific the advantages and disadvantages between field understanding of planetary boundaries help research and laboratory research. scientists determine the health of ecosystems? 3.1 What are Earth’s major spheres, and how do they 2. Summarize Why are mathematical models CROssCuttINg CONCepts support life? an important tool for studying complex natural 4. Stability and Change use the text and your own • Earth’s capacity to support life depends on the proper functioning of, and interaction systems? research to argue for or against the view that we among, four major planetary spheres. The major planetary spheres are the atmosphere are living in a new era called the Anthropocene. (air), hydrosphere (water), geosphere (land), and biosphere (living things).

3.2 What are the major ecosystem components? TYING IT ALL TOGETHER • Ecology is the study of how organisms interact with one another and their nonliving The Energy cost of cutting Rain Forests environment of matter and energy. Ecologists focus on one or more levels of organization. • Ecosystems are composed of abiotic and biotic factors. Species are classified into trophic The Case Study at the beginning use the table to help you answer “Damage to rain forests results in less levels based on how they obtain food. Producers make their own food, while consumers of this chapter discusses the the questions that follow. harm to Earth’s life support system than feed on other organisms or the wastes and remains of other organisms. importance of the world’s 1. Highly complex ecosystems are damage to simpler ecosystems because • Consumers are herbivores, carnivores, omnivores, or decomposers. Decomposers incredibly diverse tropical rain relatively resilient, meaning they complex ecosystems are more resilient to recycle nutrients back to the producers by decomposing the wastes and remains of other forests. Producers in rain forests are likely to recover over time change.” organisms. rely on solar energy to produce a from “small” changes, such as vast amount of biomass through the loss of a species. Explain this FigurE 3-23 photosynthesis. A huge variety in terms of food webs. 3.3 What happens to energy in an ecosystem? of forest species take part in and 2. Even highly complex ecosystems Ecosystem / life Average Net • Life is sustained by the one-way flow of energy, mainly from the sun, through the depend on the flow of the sun’s cannot recover from extreme Zone Primary Productivity biosphere. Energy flows through ecosystems in food chains and food webs. The amount of energy and cycling of nutrients changes. Give an example of a (kcal / m2 / year) energy available to organisms decreases at each successive trophic level. through the ecosystem. In other change from which a rain forest • Gross primary productivity (GPP) is the rate at which plants convert solar energy into words, rain forests are highly would likely not recover. Terrestrial Ecosystems chemical energy. The net primary productivity (NPP) is the rate at which producers use complex and highly productive. 3. Look at the units for NPP in Swamp and marsh 9,000 photosynthesis to produce and store chemical energy minus the rate at which they release Recall that net primary Figure 3-23. Kilocalorie (kcal) some of this stored energy through aerobic respiration. productivity (NPP) is the rate at is a unit of energy. Develop a Tropical rain forest 9,000 which producers can make the formula to determine the impact Temperate forest 5,800 chemical energy that is potentially of clear-cutting one square 3.4 What happens to matter in an ecosystem? Taiga 3,400 available to the rest of the meter per year on the energy • The flow of energy drives the cycling of matter within Earth’s biosphere. Matter in an organisms in an ecosystem. Figure produced by an ecosystem. Savanna 3,000 ecosystem travels in the form of nutrients. These nutrients cycle in and among ecosystems 2 3-23 provides an estimated annual 4. An estimated 5,000 m of Woodland and 2,600 and the biosphere, geosphere, hydrosphere, and atmosphere. average NPP for Earth’s major Amazon rain forest is cleared shrubland • Four key nutrient cycles are the water cycle, carbon cycle, nitrogen cycle, and phosphorus Temperate types of ecosystems. annually. Use your formula to 2,200 cycle. Human activities affect all four cycles. grassland Look through the table in light calculate the impact on NPP. of all you have learned about 5. Compare your answer from item Tundra 600 how energy moves through 4 to the impact of clear-cutting Desert scrub 200 3.5 How do scientists study ecosystems? • Scientists use field and laboratory research, in addition to mathematical and other models, ecosystems. What meaning can be an equal area of desert scrub. Aquatic Ecosystems drawn from these numbers? In this 6. Work with a partner. Use your to learn about ecosystems. exercise, you will analyze these answers from items 1–4 to help Estuary 9,000 • Research indicates that four out of nine planetary boundaries, or tipping points, have likely data and synthesize ideas from this you evaluate the statement lake and stream 2,200 been exceeded. Scientists need to generate more data to determine the current state of these and other possible planetary tipping points. chapter with your own thinking. below. Revise the statement and Continental shelf 1,500 add 1–2 paragraphs that explain your reasoning. Support your Open ocean 1,100 argument with data.

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CHApTER 3 ASSESSMENT

Review Key terms Review Key Concepts 30. What would happen to an ecosystem if 31. explain the importance of the roles of microbes in select the term that best fits the definition. Not all 13. name and describe four large-scale systems, or a. all decomposers and detritus feeders were the biosphere. terms will be used. spheres, that sustain life on earth. eliminated? 32. research indicates that we may have exceeded four b. all producers were eliminated? 14. define organism, population, communities, planetary boundaries. describe how exceeding each aerobic geosphere phosphorus c. all insects were eliminated? ecosystems, and the biosphere. of these boundaries might affect you, your children, respiration greenhouse cycle d. only producers and decomposers existed? or your grandchildren. anaerobic effect photosynthesis 15. Which level(s) of organization are the main focus of respiration groundwater primary Vitor Becker’s work? Anthropocene gross primary consumer aquifer productivity producer 16. Give two examples each of abiotic factors and biotic atmosphere herbivore secondary factors found in a tropical rain forest. biosphere Holocene consumer Chapter Activities carbon cycle hydrologic cycle stratosphere 17. What are decomposers? What purpose do they carnivore hydrosphere surface runoff serve in an ecosystem? consumer net primary tertiary A.Develop Models: greenhouse effect 18. summarize the process of photosynthesis. decomposer productivity consumer the greenhouse effect provides the warmth needed 1. describe how your model will work using a diagram nitrogen cycle trophic level detritivore 19. summarize the process of aerobic respiration. to sustain life in earth’s troposphere. the greenhouse to show the flow of energy through your system. food chain nutrient cycle troposphere effect is produced by an interaction between the Build and test your model. food web omnivore 20. define and distinguish between a food chain and a food web. sun and earth’s atmosphere (Lesson 3.1). Look at the 2. how did your model demonstrate the greenhouse materials below. design a model of the greenhouse 1. process in which solar energy interacts with carbon 21. distinguish between gross primary productivity effect? effect using these or other materials approved by dioxide, water vapor, and other gases in the air; it (Gpp) and net primary productivity (npp). your teacher. 3. What are some limitations of your model? how warms the troposphere 22. explain how nutrient cycles connect past, present, could your model be improved? 2. organisms that cannot produce their own nutrients and future life. Materials 4. how could your model be used to test the effect and get them by feeding on other organisms or their 23. how are humans affecting the water, carbon, plastic bottles thermometers heat lamps of increased carbon dioxide on atmospheric wastes and remains nitrogen, and phosphorus cycles? glass jars temperature? Write a hypothesis. 3. animals that eat both plants and animals 24. explain why we need more research about the 4. a complex network of interconnected food chains structure and condition of the world’s ecosystems. National Geographic Learning Framework 5. Component of earth’s life-support system that Attitudes | Curiosity consists of a thin spherical envelope of gases think Critically B. Citizen Science Skills | Collaboration surrounding the planet’s surface Knowledge | Critical Species 25. how would you explain the importance of tropical 6. includes all the water on or near earth’s surface rain forests to people who think such forests have plankton are microscopic producers and the primary 1. What was the name of the project, website, or 7. Component of earth’s life-support system where no connection to their lives? consumers that form the basis of earth’s ocean food app that you used? What institution is running the life is found 26. explain why energy from the sun is essential for the webs (Figure 3-15). although they may be small, their project? 8. uses oxygen to convert glucose and other organic cycling of nutrients. role in the biosphere is enormous. earth’s ocean 2. describe your findings and contributions. ecosystems collectively produce more biomass per year molecules back into carbon dioxide and water 27. explain the interaction of energy, nutrients, and than any other ecosystem. 3. What was your experience like working on the 9. an organism's feeding level within an ecosystem organisms in an ecosystem. project? do you think you will continue? 10. precipitation that sinks through soil into 28. make a list of the food you ate today. trace each yet, plankton populations are declining. Because they are so small and their habitats are so vast and 4. discuss any ideas you have to improve upon or underground layers of rock, sand, and gravel food item back to a producer species. diagram expand the project. the sequence of trophic levels that led to your inaccessible, scientists are relying on citizens to help 11. the rate at which producers convert radiant energy consumption of that food item. them gather and analyze the data they need. into chemical energy 29. Why are there so few top predators in an ecosystem Join a citizen science project asking volunteers to help 12. Continuous movement of elements and compounds when compared with the number of primary collect data on plankton or analyze video footage. then that make up nutrients through air, water, soil, rock, consumers? gather in small groups to discuss your answers to and living organisms the questions.

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070-103_ES_SE_37429_U1_C03.indd 96 1/29/16 4:53 PM 070-103_ES_SE_37429_U1_C03.indd 97 1/29/16 4:53 PM UNIT 2 PROJECT DESIGN A SYSTEM TO ASSESS A LOCAL SPECIES

In this challenge, you will get to use your own ingenuity and problem-solving skills. You will 11. What social considerations can you think of? 19. What evidence justified the change you made? work with a team to design a solution to a real environmental problem, build a model of your Refine your design to make it as safe and ethical as 20. Test your new design and compare the results to system, and test it. The problem in this case is related to a single species in your ecosystem. possible. your original design. As you well know, the parts of an ecosystem are interconnected: A change in one species’ 12. Create your model and carry out your test. Record 21. What claims can you make about your solution? Use population can affect the entire ecosystem. your data in a table. evidence to support your claims. Have you heard about a plant or animal species in your area that may be a cause for concern? For example, maybe there is an invasive Defining Analyzing Data and Using Math insect or weed that is affecting local businesses. Perhaps a top problems Obtaining, Evaluating, and 13. Analyze your data. What patterns do you notice? Communicating Information predator is disappearing or recently moved into your area. Obtaining, Maybe an important pollinating insect or bird is on the evaluating, and Developing and 14. What limitations exist in your data? 22. Present your team’s solution to the class. Describe communicating using models how your system works and how it was optimized to decline and no one knows why. Or maybe a migrating information 15. How well does your system meet each of the meet the criteria. Summarize your testing process species has changed its patterns. Whether it is an criteria from step 3? invasive species on the rise, a pollinating species on the and the results. decline, or another issue, you will select an organism Engineering 23. Offer thoughtful and specific criticism of other in your area that needs better monitoring and come up Forming Planning Designing Solutions arguments DESIGN CYCLE and teams’ designs. with a new method to capture data about it. from carrying out 16. What were the strengths and weaknesses of your evidence investigations 24. Conduct follow-up research. Do your data and The process of testing an engineering design involves design? observations match up with those in the studies? a series of practices similar to the practices used by 17. How can your design be improved? Revise your 25. Write a scientific question that could be asked using scientists to test hypotheses. Engineering usually involves description and diagram accordingly. your proposed design solution. many rounds of testing and retesting, so the process of Designing Analyzing solutions data and using design is often depicted as a cycle rather than a series of steps. math 26. Write a final report. Include recommendations for Engineers use this cycle to translate ideas into practical solutions. Forming Arguments from Evidence further changes, testing, and scientific research. 18. Describe how you revised your design.

Defining Problems Developing and Using Models 1. Look at the list of local species provided by your 5. Brainstorm ideas for a solution with your team. teacher. Select one species. Use the Internet to Consider the factors provided by your teacher. learn about the problem associated with your 6. Discuss two different ideas in more depth with your species. Nature centers and university extension team. Then choose one idea to carry out. offices are also great resources for research. 7. Describe the design of your system both in words • What species will your team focus on? Include the and with a diagram or flow chart. scientific name and the common name. • What is the problem associated with the species? 8. Develop a simplified version of your system that your team can use to test your ideas. Keep in mind 2. Identify a need that underlies the problem. that you will evaluate your model using the criteria • What data might help solve the problem? from step 3. • How could a system of cell phones be used to gather that data? Planning and Carrying Out Investigations 3. What would a successful solution be able to 9. Plan a test of your model with your group. Write out achieve? List the criteria. your plan in steps. 4. Consider a possible population assessment system 10. How reliable do you think your data will be? that uses cell phones. List the design constraints, Consider limitations and refine your design such as time, equipment, or people. accordingly.

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036-037_ES_SE_37429_EU_U2_C06.indd 204 3/1/16 3:26 PM 036-037_ES_SE_37429_EU_U2_C06.indd 205 3/1/16 3:27 PM Check out these exciting new National Geographic features in Environmental Science: Sustaining Your World!

Into the Okavango with National Geographic Join National Geographic Explorers Steve Boyes and Shah Selbe on a live-data biodiversity survey in the Okavango Delta in Africa. Home to one of the largest elephant populations in the world, this inland delta was declared the 1,000th UNESCO World Heritage Site in 2015. Let the Okavango story be your introduction to the environmental issues that shape our world today.

Citizen Science and National Geographic’s BioBlitzes Learn how to contribute to an understanding of biodiversity through citizen science, the collection and analysis of data from the natural world by the general public and scientists working together. Read about some well-known citizen science projects, including National Geographic’s collaboration with the National Parks Service to host student-conducted species inventories in U.S. national parks—most recently, Hawai`i Volcanoes National Park (shown here).

Partners in Sustainability: Nature Museums and Preserves Meet some great resources for the study of natural history and the environment! National Geographic works with many natural history museums and nature preserves to champion conservation. These organizations often make field guides, walking maps, species specimens, and research archives available to anyone who’s interested—and best of all, many are right in your neighborhood.

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