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14867_CH04_050_072_rev2.qxd 1/11/12 5:33 PM Page 50 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION CHAPTER 4 Principles of Ecology: How Ecosystems Work © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC CHAPTER OUTLINE NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4.1 Humans and Nature: Never does nature say one thing, and wisdom another. The Vital Connections 4.2 Ecology: The Study of —Juvenal Natural Systems © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 4.3 The Structure of Natural NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Systems ost of us live our lives seemingly apart from nature. We make 4.4 Ecosystem Function our homes in cities and towns, surround ourselves with con- Spotlight on Sustainable Mcrete and steel, and drown out the songs of birds with noise. Development 4-1: The closest many of us get to nature is a romp with the family dog © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Sustainable Sewage on the grass in the backyard. A lucky few come in much closer con- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Treatment: Mimicking tact with the great outdoors through hiking, camping, canoeing, and Nature kayaking. For many of these people, though, nature is still viewed Spotlight on Sustainable as something apart from humans—a thing to protect to preserve a few Development 4-2: pristine places for people to enjoy. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Colleges and Universities NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Go Green Point/Counterpoint: 4.1 Humans and Nature: The Vital Connections Controversy over Extinction Hard as it may be for many people to accept, human beings are part of the fabric of life. We are a part of nature. We are dependent on the Earth and natural systems in © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC thousands of ways and are an integral part of the cycles of nature. Consider our de- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 50 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 14867_CH04_050_072_rev2.qxd 1/6/12 1:14 PM Page 51 CRITICAL THINKING Throughout this chapter, we explore our connections to Exercise the living world. We examine the ways in which human sys- tems depend on natural systems and the ways in which hu- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC The information gained from various fields of mans affect them. One of the goals of this chapter is to help NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION science such as ecology is often loosely trans- you understand how nature works and how we can work bet- lated in the public arena. Terms are some- ter with nature to create a sustainable future. You will find times misinterpreted. Facts are taken out of that a great many of the lessons learned from the study of ecol- context. New findings are given more cre- ogy can be applied to human GO GREEN society. Before we begin our © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC dence than they deserve, and old, disproved journey, however, let me say Check out current efforts to NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ideas remain in the popular thinking for a green your campus and become long time. As you read this chapter, make a a few words about the term list of terms, ideas, concepts, and facts you ecology. an active participant! If your encounter that contradict what you thought Ecologyis probably one college or university isn’t ac- of the most misused words tively pursuing ways to go was true. in the English language. Ban- green, consider organizing an © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ners proclaim, “Save Our effort with key student orga- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ecology.” Speakers argue nizations, faculty members, and administrators. Chances are that “our ecology is in dan- there are plenty of environ- pendence first by taking a look around the room in which you ger,” and others talk about mentally active faculty and are sitting. Everything in that room comes from the Earth or the “ecological movement.” staff that would love to help a natural system. The clothes you wear, your morning tea or These common uses of the out. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC coffee, and even the cornflakes you ate for breakfast are word ecology are incorrect. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION products of the Earth—the soil, water, air, and plants. Why? Like all other species, humans depend on the soil, air, Ecologyis a branch of science. It describes and quanti- water, sun, and a host of living organisms to survive. Each fies the web of interactions in the environment. But ecol- year, in fact, human beings (and other animals) consume ogy is not synonymous with the word environment. Thus, enormous quantities of oxygen, which is used in the cells of © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC we can save our ecology department and ecology textbooks, our bodies to break down food molecules to generate en- but we cannot save our ecology. Our ecology is not in dan- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ergy. Oxygen is produced by plants and algae. Without these ger, but our environment is. You cannot join the ecology organisms, humans and other animals could not survive. movement, but you would be a welcome addition to the Trees, grasses, and other plants also provide a host of addi- environmental movement. tional free services. For example, plants protect the water- KEY CONCEPTS sheds near our homes, preventing flooding and erosion. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Swamps purify the water in streams and lakes—water many Ecology is a field of science that seeks to describe relationships NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION of us drink. Birds help to control insect populations. between organisms and their chemical and physical environment. Clearly, nature serves us well. Although many of us have isolated ourselves from nature, we still depend on nature in many ways. We have not emancipated ourselves from it at 4.3 The Structure all. We also influence natural cycles, and therefore, as Chap- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ter 1 explained, not only do we depend on nature, the fate of Natural Systems NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION of natural systems depends on us. In order to understand ecology, you must study the structure KEY CONCEPTS of natural systems. We begin with the biosphere. Humans are a part of nature, dependent on natural systems for a variety of economically important resources and ecological The Biosphere © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC services essential to our survival and long-term prosperity. The science of ecology focuses much of its attention on bi- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ological systems, examining their components and inter- 4.2 actions. The largest biological system is the biosphere Ecology: The Study (BI-oh-sfere), the skin of life on planet Earth. As shown in of Natural Systems FIGURE 4-1, the biosphere forms at the intersection of air, water, and land. In fact, all living organisms consist of com- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC This chapter explores ecology, the study of living organisms ponents derived from these three realms. The carbon atoms NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION and the web of relationships that binds all of us together in in body proteins, for example, come from carbon dioxide in nature. Professor Garrett Hardin, a world-renowned ecologist, the atmosphere. Carbon dioxide is captured by plants and wrote that ecology takes as its domain the entire living world. made into food molecules by a process known as photo- Ecologists study how organisms interact with one another and synthesis. Animals eat plants; the food molecules then be- how they interact with the abiotic, or nonliving, components come the building blocks of proteins and other important © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC of the environment (sunlight, for example). molecules in animals. The minerals in the bones of animals NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 51 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 14867_CH04_050_072_rev2.qxd 1/6/12 1:14 PM Page 52 Sun Atmosphere (air) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Heat NOT FOR SALE OR DISTRIBUTION Heat NOT FOR SALE OR DISTRIBUTION Heat © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Lithosphere (earth) Hydrosphere (water) FIGURE 4-1 The biosphere. The biosphere exists at the intersection of land, air, and water. Organisms derive essential minerals and other substances from © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC these three spheres. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION come from the soil, again through plants. Water comes di- for instance, may be used by a rice plant during photosyn- rectly from streams and lakes and plant matter. thesis next month in Indonesia. Those carbon dioxide mole- The biosphere extends from the bottom of the ocean, ap- cules will be incorporated into carbohydrate produced by the proximately 11,000 meters (36,000 feet) below the surface, plant and stored in the seed. Consumed by an Indonesian to the tops of the highest mountains, about 9,000 meters boy, the carbohydrate will be broken back down during cel- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC (30,000 feet) above sea level. Although that may seem like lular energy production. The carbon dioxide molecules are re- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION a long way, it’s really not. In fact, if the Earth were the size leased into the atmosphere. Without this and dozens of other of an apple, the biosphere would be about the thickness of recycling processes, all life on the planet would grind to a its skin. Although life exists throughout the biosphere, it is halt. Protecting the environment, then, helps to protect global rare at the extremes, where conditions for survival are less recycling systems on which we all depend. than optimum. Most living things are concentrated in a nar- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC row band extending from less than 200 meters (600 feet) KEY CONCEPTS NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION below the surface of the ocean to about 6,000 meters (20,000 The biosphere is an enormous biological system, spanning the feet) above sea level. entire planet. The materials within this closed system are recy- The biosphere is a closed system, much like a sealed cled over and over in order for life to be sustained. The only out- terrarium. By definition, a closed system receives no materi- side contribution to the biosphere is sunlight, which provides als from the outside. The only outside contribution is sunlight, energy for all living things. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC which is vital to the health and well-being of virtually all life. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Sunlight powers almost all life on the planet. Even the en- Biomes and Aquatic Life Zones ergy released by the combustion of coal, oil, and natural gas (which we use to power our homes and factories) comes from The biosphere consists of terrestrial and aquatic systems. sunlight that fell on the Earth several hundred million years ago. Viewed from outer space, the Earth—the terrestrial portion of Because the Earth is a closed system, all materials neces- the biosphere—resembles a giant jigsaw puzzle, consisting © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC sary for life must be recycled. The carbon dioxide you exhale, of large landmasses among vast expanses of ocean. The land- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 52 PART II. Natural Systems/Human Systems: Searching for a Sustainable Relationship © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 14867_CH04_050_072_rev2.qxd 1/6/12 1:14 PM Page 53 © Jones & Bartlett Learning, LLC Ice © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tropic of Cancer © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Equator NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tropic of Capricorn © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tundra Temperate grassland Tropical scrub forest © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Mountains Arid grassland, Tropical rain forest, (complex zonation) semidesert tropical evergreen forest Taiga (northern Desert Tropical deciduous forest coniferous forest) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Temperate forest Chapparal/Mediterranean Tropical savanna, NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION thorn forest FIGURE 4-2 Biomes. This map shows the world’s major biomes. masses, or continents, can be divided into fairly large regions cause the subsoil (called permafrost) remains frozen year © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC called biomes(FIGURE 4-2). A biomeis a terrestrial portion of round, preventing the deep root growth necessary for trees. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the biosphere characterized by a distinct climate and a particular Immediately south of the tundra lies the taiga(TIE-ga), assemblage of plants and animals adapted to it.1 Chapter 5 also known as the northern coniferousor boreal forest.The describes the biomes in detail. This section provides an taiga’s milder climate and longer growing season result in a overview. greater diversity and abundance of plant and animal life than In a biome, abiotic conditions—such as soil type, tem- exists on the tundra. Evergreen trees, bears, wolverines, and © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC perature, and rainfall—determine the plant communities moose are characteristic species (FIGURE 4-3b). NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION that can survive. These, in turn, determine which animals can East of the Mississippi River lies the temperate decid- subsist. As illustrated in Figure 4-2, the North American uous forest biome, characterized by an even warmer cli- continent contains seven major biomes, five of which are mate and more abundant rainfall (FIGURE 4-3c). Broad-leaved discussed here. Starting in the north is the tundra(TON-dra), trees make their home in this biome. Opossums, black bears, a region of long, cold winters and rather short growing sea- squirrels, and foxes are characteristic animal species. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC sons (FIGURE 4-3a). The rolling terrain of the tundra sup- West of the Mississippi lies the grassland biome (FIG- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ports grasses, mosses, lichens, wolves, musk oxen, and other URE 4-3d). Inadequate rainfall and periodic drought prevent animals adapted to the bitter winter cold. Trees cannot grow trees from growing on the grasslands, except near rivers, on the tundra because of the short growing season and be- streams, and human habitation. Over the years, deep-rooted grasses have evolved on the plains. These grasses can with- 1 stand fire, drought, and grazing even in arid grasslands. Coy- Although each biome has its specific climate, there can be con- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC siderable climatic variation within a given biome. otes, hawks, and voles are characteristic animal species. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION CHAPTER 4: Principles of Ecology: How Ecosystems Work 53 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.
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