Ecology_MrSapora
Slade Sapora Jean Brainard, Ph.D. Ck12 Science Dana Desonie, Ph.D. Douglas Wilkin, Ph.D.
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AUTHORS Slade Sapora Jean Brainard, Ph.D. Ck12 Science Dana Desonie, Ph.D. Douglas Wilkin, Ph.D.
CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the FlexBook®, CK-12 intends to pioneer the generation and distribution of high-quality educational content that will serve both as core text as well as provide an adaptive environment for learning, powered through the FlexBook Platform®. Copyright © 2012 CK-12 Foundation, www.ck12.org The names “CK-12” and “CK12” and associated logos and the terms “FlexBook®” and “FlexBook Platform®” (collectively “CK-12 Marks”) are trademarks and service marks of CK-12 Foundation and are protected by federal, state, and international laws. Any form of reproduction of this book in any format or medium, in whole or in sections must include the referral attribution link http://www.ck12.org/saythanks (placed in a visible location) in addition to the following terms. Except as otherwise noted, all CK-12 Content (including CK-12 Curriculum Material) is made available to Users in accordance with the Creative Commons Attribution/NonCommercial/Share Alike 3.0 Unported (CC BY-NC-SA) License (http://creativecommons.org/licenses/by-nc-sa/3.0/), as amended and updated by Creative Commons from time to time (the “CC License”), which is incorporated herein by this reference. Complete terms can be found at http://www.ck12.org/terms. Printed: February 3, 2013
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Contents
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Contents 1
Introduction to Ecology
1
2
What are Biomes?
4
3
Levels of Ecological Organization
7
4
Producers
10
5
Consumers and Decomposers
13
6
Food Webs
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7
Energy
19
8
Energy Pyramids
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9
Flow of Matter in Ecosystems
24
10 The Water Cycle
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11 The Carbon Cycle
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12 Ecosystems
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13 Habitat and Niche
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14 Bird Ecology
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15 Nonrenewable Resources
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16 Habitat Destruction
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17 Importance of Biodiversity
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C HAPTER
Chapter 1. Introduction to Ecology
1
Introduction to Ecology
• Define ecology. • Distinguish between abiotic and biotic factors.
Do organisms live in isolation? No, organisms are not separated from their environment or from other organisms. They interact in many ways with their surroundings. For example, this deer may be drinking from this stream or eating nearby plants. Ecology is the study of these interactions. Introduction to Ecology
Life Science can be studied at many different levels. You can study small things like cells. Or you can study big things like a group of animals. You can also study the biosphere, which is any area in which organisms live. The study of the biosphere is part of ecology, the study of how living organisms interact with each other and with their environment. Research in Ecology
Ecology involves many different fields, including geology, soil science, geography, meteorology, genetics, chemistry, and physics. You can also divide ecology into the study of different organisms, such as animal ecology, plant ecology, insect ecology, and so on. Ecologists also study biomes. A biome is a large community of plants and animals that live in the same place. For example, ecologists can study the biomes as diverse as the Arctic, the tropics, or the desert (Figure 1.1). They may want to know why different species live in different biomes. They may want to know what would make a particular biome or ecosystem stable. Can you think of other aspects of a biome or ecosystem that ecologists could study? Ecologists do two types of research: 1
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FIGURE 1.1 An example of a biome, the Atacama Desert, in Chile.
1. Field studies. 2. Laboratory studies. Field studies involve collecting data outside in the natural world. An ecologist who completes a field study may travel to a tropical rain forest to study, count, and classify all of the insects that live in a certain area. Laboratory studies involve working inside, usually in a controlled environment. Sometimes, ecologists collect data from the field, and then they analyze that data in the lab. Also, they use computer programs to predict what will happen to organisms that live in a specific area. For example, they may make predictions about what happens to insects in the rainforest after a fire. Organisms and Environments
All organisms have the ability to grow and reproduce. To grow and reproduce, organisms must get materials and energy from the environment. Plants obtain their energy from the sun through photosynthesis, whereas animals obtain their energy from other organisms. Either way, these plants and animals, as well as the bacteria and fungi, are constantly interacting with other species as well as the non-living parts of their ecosystem. An organism’s environment includes two types of factors: 1. Abiotic factors are the parts of the environment that are not living, such as sunlight, climate, soil, water, and air. 2. Biotic factors are the parts of the environment that are alive, or were alive and then died, such as plants, animals, and their remains. Biotic factors also include bacteria, fungi and protists. Ecology studies the interactions between biotic factors, such as organisms like plants and animals, and abiotic factors. For example, all animals (biotic factors) breathe in oxygen (abiotic factor). All plants (biotic factor) absorb carbon dioxide (abiotic factor) and need water (abiotic factor) to survive. Can you think of another way that abiotic and biotic factors interact with each other? Vocabulary
• abiotic factor: Aspect of the environment that is not a living organism, such as soil, water or air. 2
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Chapter 1. Introduction to Ecology
• biome: Large community of plants and animals distinguished by the dominant forms of animal and plant life and the climate. • biotic factor: Components of the environment that are living, or were alive and then died, such as plants or animals. • biosphere: Part of the planet and atmosphere with living organisms. • ecology: Study of how living organisms interact with each other and with their environment. • photosynthesis: Process by which specific organisms (including all plants) use the sun’s energy to make their own food from carbon dioxide and water; process that converts the energy of the sun, or solar energy, into carbohydrates, a type of chemical energy. Summary
• Ecology is the study of how living organisms interact with each other and with their environment. • Abiotic factors are the parts of the environment that have never been alive, while biotic factors are the parts of the environment that are alive, or were alive and then died. Practice
Use the resource below to answer the questions that follow. • A Study in Stream Ecology at USGS http://gallery.usgs.gov/videos/449#.UKWeJId9KSo (6:57)
MEDIA Click image to the left for more content.
1. What are some of the abiotic factors that scientists monitor when dealing with stream ecosystems? 2. What are some of the biotic factors that scientists monitor when dealing with stream ecosystems? 3. Remembering what you’ve learned about the scientific process, why is it valuable for scientists to use the same procedures and gather the same information across different streams and a wide ranging geography? What does this allow them to do? How does this affect the strength and applicability of their research? 4. What is a "benchmark" in ecology? Why are they essential? 5. Why is it important to have a reference stream if you want to gauge the effects of Homo sapiens on streams? What characteristics should this reference stream have? 6. How does water pollution seem to be affecting diversity in some streams? What data would be necessary to prove the pollution is the causative agent affecting stream biodiversity? Review
1. What do ecologists study? 2. In a forest, what are some biotic factors present? Abiotic factors?
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C HAPTER
2
What are Biomes?
• Define biome and describe how they are classified.
Where was this picture taken? This scene is from southern California. However, deserts exist around the globe. You might find a similar picture of a desert in Africa. The desert is one type of biome. What are Biomes?
Tropical rainforests and deserts are two familiar types of biomes. A biome is an area with similar populations of organisms. This can easily be seen with a community of plants and animals. Remember that a community is all of the populations of different species that live in the same area and interact with one another. Different biomes, such as a forest (Figure 2.1) or a desert, obviously have different communities of plants and animals. How are the plants and animals different in the rainforest than those in the desert? Why do you think they are so different? The differences in the biomes are due to differences in the abiotic factors, especially climate. Climate is the typical weather in an area over a long period of time. The climate includes the amount of rainfall and the average temperature in the region. Obviously, the climate in the desert is much different than the climate in the rainforest. As a result, different types of plants and animals live in each biome. There are into two major groups of biomes: 1. Terrestrial biomes, which are land-based, such as deserts and forests. 2. Aquatic biomes, which are water-based, such as ponds and lakes. The abiotic factors, such as the amount of rainfall and the temperature, are going to influence other abiotic factors, such as the quality of the soil. This, in turn, is going to influence the plants that migrate into the ecosystem and thrive 4
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Chapter 2. What are Biomes?
FIGURE 2.1 Tropical rainforest landscape in Malaysia. Notice how the plants are different from those in the desert.
in that biome. Recall that migration is the movement of an organism into or out of a population. It can also refer to a whole new species moving into a habitat. The type of plants that live in a biome are going to attract a certain type of animal to that habitat. It is the interaction of the abiotic and biotic factors that describe a biome and ecosystem.
Vocabulary
• • • • • • • •
abiotic factor: Nonliving aspect of the environment. aquatic biome: Biome that is based in the water, such as ponds, lakes, streams, or oceans. biome: Area with similar climate that includes similar communities of plants and animals. biotic factor: Living aspects of the environment. climate: Typical weather in an area over a long period of time. habitat: Ecological or environmental area in which a particular species live. migration: Movement of individual organisms into, or out of, a population. terrestrial biome: Biome that is based on land, such as a desert or rainforest.
Summary
• A biome is an area with similar climate that includes similar communities of plants and animals. • Climate influences the types of plants and animals that inhabit a specific biome.
Practice
Use the resources below to answer the questions that follow. • Biomes at http://www.youtube.com/watch?v=ag5ATGEplbU (7:50)
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MEDIA Click image to the left for more content.
1. Where do tundra biomes primarily occur? How much precipitation do these areas see annually? 2. What areas are best known for having Taiga biomes? What is the temperature range this biome experiences? 3. What is a behavioral adaptation that animals in desert biomes display? • Earth’s Biomes at http://www.forgefx.com/casestudies/prenticehall/ph/biomes/biomes.htm 1. How many months a year is the temperature in La Paz, Bolivia above 15C? How many months a year is it below 5C? What kind of biome is it located in? 2. How many months a year is the temperature in Quebec, Canada above 15C? How many months a year is it below 5C? What kind of biome is it located in? 3. How many months a year does Quillayute, WA, USA receive more than 30cm of precipitation? How many months a year does it receive less than 5cm of precipitation? What kind of biome is it located in? 4. How many months a year does Cairo, Egypt receive more than 30cm of precipitation? How many months a year does it receive less than 5cm of precipitation? What kind of biome is it located in? 5. How many months a year does Jakarta, Indonesia receive more than 30cm of precipitation? How many months a year does it receive less than 5cm of precipitation? What kind of biome is it located in? Review
1. What is a biome? 2. Give two examples of terrestrial biomes.
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C HAPTER
Chapter 3. Levels of Ecological Organization
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Levels of Ecological Organization
• Describe the levels of organization in ecology.
How is your school organized? Your school is organized at several levels. Individual students and teachers are divided into classes. These classes are organized into an entire middle school. Your middle school and other nearby schools are organized into a school district. Just like schools are organized, ecosystems are also organized into several different levels, and an ecosystem can be studied at any one of the various levels of organization. Levels of Ecological Organization
Ecosystems can be studied at small levels or at large levels. The levels of organization are described below from the smallest to the largest: • A species is a group of individuals who are genetically related and can breed to produce fertile young. Individuals are not members of the same species if their members cannot produce offspring that can also have children. The second word in the two word name given to every organism is the species name. For example, in Homo sapiens, sapiens is the species name. • A population is a group of organisms belonging to the same species that live in the same area and interact with one another. • A community is all of the populations of different species that live in the same area and interact with one another. • An ecosystem includes the living organisms (all the populations) in an area and the non-living aspects of the environment (Figure 3.1). An ecosystem is made of the biotic and abiotic factors in an area.
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FIGURE 3.1 Satellite image of Australia’s Great Barrier Reef, an example of a marine ecosystem.
• The biosphere is the part of the planet with living organisms (Figure 3.2). The biosphere includes most of Earth, including part of the oceans and the atmosphere.
FIGURE 3.2 The global biosphere, which includes all areas that contain life, from the sea to the atmosphere.
Ecologists study ecosystems at every level, from the individual organism to the whole ecosystem and biosphere. They can ask different types of questions at each level. Examples of these questions are given in Table 3.1, using the zebra (Equus zebra) as an example.
TABLE 3.1: Ecological Ecosystems Level Individual Population Community Ecosystem Biosphere
Question How do zebras keep water in their bodies? What causes the growth of a zebra populations? How does a disturbance, like a fire or predator, affect the number of mammal species in African grasslands? How does fire affect the amount of food available in grassland ecosystems? How does carbon dioxide in the air affect global temperature?
Vocabulary
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biosphere: Region of the earth that is home to living things. community: All of the populations of different species that live in the same area and interact with one another. ecosystem: All the living things in an area interacting with all of the non-living parts of the environment. population: Group of organisms belonging to the same species that live in the same area and interact with one another. • species: Group of individuals that are genetically related and can breed to produce fertile young. • • • •
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Chapter 3. Levels of Ecological Organization
Practice
Use the resource below to answer the questions that follow. • Ecology Levels and Populations at http://www.youtube.com/watch?v=1JSS8XIYcgU (5:31)
MEDIA Click image to the left for more content.
1. What is the relationship between an individual and a community? 2. What characteristics define a population? Why is identification of characteristics important to compare populations? 3. Why is the distinction between a community and an ecosystem important to ecologists? What kinds of questions could be answered by looking at the community level of organization? What kinds of questions could be answered by looking at the ecosystem level of organization? When answering this question keep in mind the need to control variables in scientific experiments. Review
1. How is an ecosystem different from a community? 2. How is a population different from a community?
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C HAPTER
4
• Explain where all the energy in an ecosystem comes from. • Describe how energy enters an ecosystem.
Where does all the bear’s energy come from? 10
Producers
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Chapter 4. Producers
Bears get their energy from their food. Brown bears eat a varied diet, from nuts and berries to fish and other animals. When bears eat a berry, they are obtaining energy that the plant originally captured from the sun. Even when the bear eats an animal, the energy in that animal ultimately came from eating a producer that captured the sun’s energy. Producers
Energy is the ability to do work. In organisms, this work can be physical work, like walking or jumping, or it can be the work used to carry out the chemical processes in their cells. Every biochemical reaction that occurs in an organism’s cells needs energy. All organisms need a constant supply of energy to stay alive. Some organisms can get the energy directly from the sun. Other organisms get their energy from other organisms. Through predator-prey relationships, the energy of one organism is passed on to another. Energy is constantly flowing through a community. With just a few exceptions, all life on Earth depends on the sun’s energy for survival. The energy of the sun is first captured by producers (Figure 4.1), organisms that can make their own food. Many producers make their own food through the process of photosynthesis. The "food" the producers make is the sugar, glucose. Producers make food for the rest of the ecosystem. As energy is not recycled, energy must consistently be captured by producers. This energy is then passed on to the organisms that eat the producers, and then to the organisms that eat those organisms, and so on. Recall that the only required ingredients needed for photosynthesis are sunlight, carbon dioxide (CO2 ), and water (H2 O). From these simple inorganic ingredients, photosynthetic organisms produce the carbohydrate glucose (C6 H12 O6 ), and other complex organic compounds. Essentially, these producers are changing the energy from the sunlight into a usable form of energy. The survival of every ecosystem is dependent on the producers. Without producers capturing the energy from the sun and turning it into glucose, an ecosystem could not exist. On land, plants are the dominant producers. Phytoplankton, tiny photosynthetic organisms, are the most common producers in the oceans and lakes. Algae, which is the green layer you might see floating on a pond, are an example of phytoplankton. There are also bacteria that use chemical processes to produce food. They get their energy from sources other than the sun, but they are still called producers. This process is known as chemosynthesis, and is common in ecosystems without sunlight, such as certain marine ecosystems.
FIGURE 4.1 Producers include plants (a), algae (b), and diatoms (c).
Vocabulary
• chemosynthesis: Process of using the energy in chemical compounds to make food; characteristic of produc11
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• • •
• • •
ers in ecosystems without sunlight. energy: Ability to do work. glucose: Simple sugar molecule with the chemical formula C6 H12 O6 . photosynthesis: Process by which specific organisms (including all plants) use the sun’s energy to make their own food from carbon dioxide and water; process that converts the energy of the sun, or solar energy, into carbohydrates, a type of chemical energy. phytoplankton: Tiny photosynthetic organisms that are producers in aquatic ecosystems. predator-prey relationship: Interaction between two organisms of unlike species; one organism acts as predator that captures and feeds on the other organism, which serves as the prey. producer: Organism that produces food (glucose) for itself and other organisms.
Summary
• With just a few exceptions, all life on Earth depends on the sun’s energy for survival. • Producers make food for the rest of the ecosystem through the process of photosynthesis, where the energy of the sun is used to convert carbon dioxide and water into glucose. Practice
Use the resource below to answer the questions that follow. • Producers and Consumers at http://www.youtube.com/watch?v=P0a97kS_3SA (1:59)
MEDIA Click image to the left for more content.
1. Can producers function without sunlight? Why or why not? Explain your answer fully. 2. What are some examples of producers? Why are they called autotrophs? 3. How do some producers use sunlight to make "food"? What other resources do they require? Review
1. Where does all the energy in an ecosystem ultimately come from? 2. What "ingredients" are needed for the process of photosynthesis?
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C HAPTER
Chapter 5. Consumers and Decomposers
5
Consumers and Decomposers
• Classify organisms on the basis of how they obtain energy and describe examples of each.
What is breaking down this leaf? Notice how this leaf is slowly being broken down. This process can be carried out by fungi and bacteria on the ground. Breaking down old leaves is an important process since it releases the nutrients in the dead leaves back into the soil for living plants to use. Consumers and Decomposers
Recall that producers make their own food through photosynthesis. But many organisms are not producers and cannot make their own food. So how do these organisms obtain their energy? They must get their energy from other organisms. They must eat other organisms, or obtain their energy from these organisms some other way. The organisms that obtain their energy from other organisms are called consumers. All animals are consumers, and they eat other organisms. Fungi and many protists and bacteria are also consumers. But, whereas animals eat other organisms, fungi, protists, and bacteria "consume" organisms through different methods. The consumers can be placed into different groups, depending on what they consume. • Herbivores are animals that eat producers to get energy. For example, rabbits and deer are herbivores that eat plants. The caterpillar pictured below (Figure 5.1) is an herbivore. Animals that eat phytoplankton in aquatic environments are also herbivores. • Carnivores feed on animals, either herbivores or other carnivores. Snakes that eat mice are carnivores. Hawks that eat snakes are also carnivores (Figure 5.1). 13
www.ck12.org • Omnivores eat both producers and consumers. Most people are omnivores, since they eat fruits, vegetables, and grains from plants, and also meat and dairy products from animals. Dogs, bears, and raccoons are also omnivores.
FIGURE 5.1 Examples of consumers are caterpillars (herbivores) and hawks (carnivore).
Decomposers and Stability
Decomposers (Figure 5.2) get nutrients and energy by breaking down dead organisms and animal wastes. Through this process, decomposers release nutrients, such as carbon and nitrogen, back into the environment. These nutrients are recycled back into the ecosystem so that the producers can use them. They are passed to other organisms when they are eaten or consumed. The stability of an ecosystem depends on the actions of the decomposers. Examples of decomposers include mushrooms on a decaying log. Bacteria in the soil are also decomposers. Imagine what would happen if there were no decomposers. Wastes and the remains of dead organisms would pile up and the nutrients within the waste and dead organisms would not be released back into the ecosystem. Producers would not have enough nutrients. The carbon and nitrogen necessary to build organic compounds, and then cells, allowing an organism to grow, would be insufficient. Other nutrients necessary for an organism to function properly would also not be sufficient. Essentially, many organisms could not exist.
FIGURE 5.2 Examples of decomposers are bacteria (a) and fungi (b).
Vocabulary
• carnivore: Organism that feeds on other animals. • consumer: Organism that must consume other organisms to obtain food for energy. • decomposer: Organism that obtains nutrients and energy by breaking down dead organisms and animal wastes. • herbivore: Animal that eats producers to obtain energy. • omnivore: Animal that eats both producers and consumers. • producer: Organism that produces food for itself and other organisms. Summary
• Consumers must obtain their nutrients and energy by eating other organisms. 14
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Chapter 5. Consumers and Decomposers
• Decomposers break down animal remains and wastes to get energy. • Decomposers are essential for the stability and survival of an ecosystem. Practice
Use the resource below to answer the questions that follow. • Decomposers at http://www.youtube.com/watch?v=Z6V0a_7N1Mw (3:19)
MEDIA Click image to the left for more content.
1. What is the role of decomposers in an ecosystem? What is the source of the matter which is decomposed? 2. How do the actions of earthworms improve soil quality? How does this impact the amount of biomass an ecosystem can support? 3. How do gastropods function as decomposers? Review
1. What’s the term for a consumer that eats both leaves and fish? 2. What are the different types of consumers? 3. Why are decomposers important in the ecosystem?
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C HAPTER
6
Food Webs
• Define a food web. • Be able to draw and interpret a food web.
How do the grasshopper and the grass interact? Grasshoppers don’t just hop on the grass. They also eat the grass. Other organisms also eat the grass, and some animals even eat the grasshopper. These interactions can be visualized by drawing a food web. Food Webs
Energy must constantly flow through an ecosystem for the system to remain stable. What exactly does this mean? Essentially, it means that organisms must eat other organisms. Food chains (Figure 6.1) show the eating patterns in an ecosystem. Food energy flows from one organism to another. Arrows are used to show the feeding relationship between the animals. The arrow points from the organism being eaten to the organism that eats it. For example, an arrow from leaves to a grasshopper shows that the grasshopper eats the leaves. Energy and nutrients are moving from the leaves to the grasshopper. Next, a frog might prey on the grasshopper, a snake may eat the frog, and then a hawk might eat the snake. The food chain would be: leaves → grasshopper → frog → snake → hawk. A food chain cannot continue to go on and on. For example the food chain could not be: leaves → caterpillar → spider → frog → lizard → fox → hawk. Food chains only have 4 or 5 total levels. Therefore, a chain has only 3 or 4 levels for energy transfer. In an ocean ecosystem, one possible food chain might look like this: phytoplankton → krill → fish → shark. The producers are always at the beginning of the food chain, bringing energy into the ecosystem. Through 16
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Chapter 6. Food Webs
FIGURE 6.1 This food chain includes producers and consumers. How could you add decomposers to the food chain?
photosynthesis, the producers create their own food in the form of glucose, but also create the food for the other organisms in the ecosystem. The herbivores come next, then the carnivores. When these consumers eat other organisms, they use the glucose in those organisms for energy. In this example, phytoplankton are eaten by krill, which are tiny, shrimp-like animals. The krill are eaten by fish, which are then eaten by sharks. Could decomposers be added to a food chain? Each organism can eat and be eaten by many different types of organisms, so simple food chains are rare in nature. There are also many different species of fish and sharks. So a food chain cannot end with a shark; it must end with a distinct species of shark. A food chain does not contain the general category of "fish," it will contain specific species of fish. In ecosystems, there are many food chains. Since feeding relationships are so complicated, we can combine food chains together to create a more accurate flow of energy within an ecosystem. A food web (Figure 6.2) shows the feeding relationships between many organisms in an ecosystem. If you expand our original example of a food chain, you could add deer that eat clover and foxes that hunt chipmunks. A food web shows many more arrows, but still shows the flow of energy. A complete food web may show hundreds of different feeding relationships.
FIGURE 6.2 Food web in the Arctic Ocean.
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www.ck12.org Vocabulary
• carnivore: Organism that feeds on other animals. • consumer: Organism that must consume other organisms to obtain food for energy. • decomposer: Organism that obtains nutrients and energy by breaking down dead organisms and animal wastes. • food chain: Diagram that shows feeding interactions in an ecosystem through a single pathway. • food web: Diagram that shows feeding interactions between many organisms in an ecosystem through multiple intersecting pathways. • herbivore: Animal that eats producers to obtain energy. • producer: Organism that produces food for itself and other organisms. Summary
• A food chain is a diagram that shows feeding interactions in an ecosystem through a single pathway. • A food web is a diagram that shows feeding interactions between many organisms in an ecosystem through multiple intersecting pathways. Practice
Use the resource below to answer the questions that follow. • Build A Food Web at http://www.sciencesource2.ca/resources/SS_active_art/active_art/SEinteractive_gr09_c h01_pg31/index.html 1. 2. 3. 4.
What do the Loons and Arctic Tern have in common in the food web? What do the Beluga and the sea duck have in common in the food web? What species in the food web feed on zooplankton (animal plankton)? When you build your own food web what must it contain to be healthy? How many healthy food webs could you build?
Review
1. What is the difference between a food chain and a food web? 2. What is the herbivore in the following food chain: algae ->fish ->herons?
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C HAPTER
Chapter 7. Energy
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Energy
• Define energy. • Give the SI unit for energy. • Identify different forms of energy.
These young children are very active. They seem to be brimming with energy. You probably know that lots of things have energy—from batteries to the sun. But do you know what energy is? Read on to find out. Defining Energy
Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work, which means using force to move an object over a distance. When work is done, energy is transferred from one object to another. For example, when the boy in the Figure 7.1 uses force to swing the racket, he transfers some of his energy to the racket. Q: It takes energy to play tennis. Where does this boy get his energy? A: SI Unit for Energy
Because energy is the ability to do work, it is expressed in the same unit that is used for work. The SI unit for both work and energy is the joule (J), or Newton • meter (N • m). One joule is the amount of energy needed to apply a force of 1 Newton over a distance of 1 meter. For example, suppose the boy in the Figure 7.1 applies 20 Newtons of force to his tennis racket over a distance of 1 meter. The energy needed to do this work is 20 N •m, or 20 J. 19
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FIGURE 7.1
Energy Has Many Forms
If you think about different sources of energy—such as batteries and the sun—you probably realize that energy can take different forms. For example, when the boy swings his tennis racket, the energy of the moving racket is an example of mechanical energy. To move his racket, the boy needs energy stored in food, which is an example of chemical energy. Other forms of energy include electrical, thermal, light, and sound energy. The different forms of energy can also be classified as either kinetic energy or potential energy. Kinetic energy is the energy of moving matter. Potential energy is energy that is stored in matter. Q: Is the chemical energy in food kinetic energy or potential energy? A: Q: What is an example of kinetic energy? A: Summary
• Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work. • The SI unit for energy as well as work is the joule (J), or Newton • meter (N • m). • Energy exists in different forms, such as mechanical energy and chemical energy. Most forms of energy can also be classified as either kinetic energy or potential energy. Vocabulary
• energy: Ability to cause changes in matter, or ability to do work.
Review
1. 2. 3. 4.
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How is energy defined in science? What is the SI unit for energy? Name two forms that energy may take. Which type of energy is the energy of a moving tennis ball? Is it kinetic energy or potential energy?
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C HAPTER
Chapter 8. Energy Pyramids
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Energy Pyramids
• Define energy pyramids. • Explain the flow of energy through an ecosystem using an energy pyramid.
How much energy could be gained from the warthog? If the cheetah is successful in capturing the warthog, he would gain some energy by eating it. But would the cheetah gain as much energy as the warthog has ever consumed? No, the warthog has used up some of the energy it has consumed for its own needs. The cheetah will only gain a fraction of the energy that the warthog has consumed throughout its lifetime. Energy Pyramids
When an herbivore eats a plant, the energy in the plant tissues is used by the herbivore. But how much of that energy is transferred to the herbivore? Remember that plants are producers, bringing the energy into the ecosystem by converting sunlight into glucose. Does the plant use some of the energy for its own needs? Recall the energy is the ability to do work, and the plant has plenty or "work" to do. So of course it needs and uses energy. It converts the glucose it makes into ATP through cellular respiration just like other organisms. After the plant uses the energy from glucose for its own needs, the excess energy is available to the organism that eats the plant. The herbivore uses the energy from the plant to power its own life processes and to build more body tissues. However, only about 10% of the total energy from the plant gets stored in the herbivore’s body as extra body tissue. The rest of the energy is used by the herbivore and released as heat. The next consumer on the food chain that eats the herbivore will only store about 10% of the total energy from the herbivore in its own body. This means the carnivore will store only about 1% of the total energy that was originally in the plant. In other words, only about 10% of energy of one step in a food chain is stored in the next step in the food chain. The majority of the energy is used by the organism or released to the environment. Every time energy is transferred from one organism to another, there is a loss of energy. This loss of energy can be shown in an energy pyramid. An example of an energy pyramid is pictured below (Figure 8.1). Since there is energy loss at each step in a food chain, it takes many producers to support just a few carnivores in a community. Each step of the food chain in the energy pyramid is called a trophic level. Plants or other photosynthetic organisms (autotrophs) are found on the first trophic level, at the bottom of the pyramid. The next level will be the herbivores, and then the carnivores that eat the herbivores. The energy pyramid (Figure 8.1) shows four levels of a food chain, from producers to carnivores. Because of the high rate of energy loss in food chains, there are usually only 4 or 5 trophic levels in the food chain or energy pyramid. There just is not enough energy to support any additional trophic levels. Heterotrophs are found in all levels of an energy pyramid other than the first level. 21
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FIGURE 8.1 As illustrated by this ecological pyramid, it takes a lot of phytoplankton to support the carnivores of the oceans.
Vocabulary
• ATP: Adenosine triphosphate; a molecule containing a large amount of energy that can be used for many metabolic processes in the cell. • autotroph: Organism that produces complex organic compounds from simple inorganic molecules using a source of energy such as sunlight. • cellular respiration: Process of breaking down glucose to obtain energy in the form of ATP. • energy: Ability to do work. • energy pyramid: Diagram showing how energy decreases from lower to higher trophic levels. • heterotroph: Organism which obtains carbon from outside sources. • producer: Organism that produces food (glucose) for itself and other organisms. • trophic level: Feeding position in a food chain.
Summary
• As energy is transferred along a food chain, energy is lost as heat. • Only about 10% of energy of one step in a food chain is stored in the next step in the food chain.
Practice
Use the resource below to answer the questions that follow. • Ecological Pyramids at http://www.youtube.com/watch?v=NJplkrliUEg (4:03)
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Chapter 8. Energy Pyramids
MEDIA Click image to the left for more content.
1. What are three types of ecological pyramids? How do their shapes compare? 2. Do you think it would be possible to construct a pyramid where the number of carnivores was more than the number of herbivores? Think carefully about the different possibilities. 3. Do you think it would be possible to construct a pyramid where the biomass of carnivores was more than the biomass of herbivores? How does this compare to a numbers pyramid. 4. What consumes energy at each trophic level? How does this contribute to energy loss between trophic levels? 5. What do you think you could learn about an ecosystem by comparing three different types of pyramids for an ecosystem? How is this information different than the information you could gain from looking at a single pyramid? Review
1. When an herbivore eats a plant, what happens to 90% of the energy obtained from that plant? 2. In a forest community, caterpillars eat leaves, and birds eat caterpillars. Draw an energy pyramid using this information.
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C HAPTER
9
Flow of Matter in Ecosystems
• Describe how matter flows through ecosystems. • Compare and contrast the flow of matter with the flow of energy in ecosystems.
What killed millions of sailors in the 15th through 18th centuries? Sailors at sea or explorers in polar regions, even Crusaders, who went without fresh food developed scurvy due to the lack of vitamin C in their diets. Without the right nutrients in the right amounts, you can’t live — and humans need vitamin C. It wasn’t until 1932 that the link between scurvy and a nutrient was made. Flow of Matter in Ecosystems
The flow of matter in an ecosystem is not like energy flow. Matter enters an ecosystem at any level and leaves at any level. Matter cycles freely between trophic levels and between the ecosystem and the physical environment (Figure 9.1). Nutrients
Nutrients are ions that are crucial to the growth of living organisms. Nutrients such as nitrogen and phosphorous are important for plant cell growth. Animals use silica and calcium to build shells and skeletons. Cells need nitrates and phosphates to create proteins and other biochemicals. From nutrients, organisms make tissues and complex molecules such as carbohydrates, lipids, proteins, and nucleic acids. What are the sources of nutrients in an ecosystem? Rocks and minerals break down to release nutrients. Some enter the soil and are taken up by plants. Nutrients can be brought in from other regions, carried by wind or water. When one organism eats another organism, it receives all of its nutrients. Nutrients can also cycle out of an ecosystem. 24
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Chapter 9. Flow of Matter in Ecosystems
FIGURE 9.1 Nutrients cycle through ocean food webs.
Decaying leaves may be transported out of an ecosystem by a stream. Wind or water carries nutrients out of an ecosystem. Decomposers play a key role in making nutrients available to organisms. Decomposers break down dead organisms into nutrients and carbon dioxide, which they respire into the air. If dead tissue would remain as it is, eventually nutrients would run out. Without decomposers, life on Earth would have died out long ago.
Summary
• Ions that are crucial to the growth of organisms are known as nutrients. • Decomposers break down dead organisms into nutrients and gases so that they can be used by other organisms. • Nutrients can enter or exit an ecosystem at any point and can cycle around the planet.
Practice
Use this resource to answer the questions that follow. http://www.powerhouseanimation.com/gallery/projectArchive/publishers-resource-group/prg_flowOfEnergy.swf 1. What is carbon dioxide in the air a reservoir for? 2. What do producers do with carbon? 3. What do herbivores do with carbon? 4. Why is the biomass of carnivores less than herbivores? 5. What do decomposers do? 6. How is carbon returned to the atmosphere?
Review
1. How does the flow of matter differ from the flow of energy through an ecosystem? 25
www.ck12.org 2. How do nutrients enter and exit and ecosystem? 3. What would happen to life on Earth if there were no decomposers?
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C HAPTER
Chapter 10. The Water Cycle
10
The Water Cycle
• Define a biogeochemical cycle. • Describe the key features of the water cycle.
Could you be drinking the same water as George Washington? Water is recycled constantly through the ecosystem. That means any water you drank today has been around for millions of years. You could be drinking water that was once drunk by George Washington, the first humans, or even the dinosaurs. The Water Cycle
Whereas energy flows through an ecosystem, water and elements like carbon and nitrogen are recycled. Water and nutrients are constantly being recycled through the environment. This process through which water or a chemical 27
www.ck12.org element is continuously recycled in an ecosystem is called a biogeochemical cycle. This recycling process involves both the living organisms (biotic components) and nonliving things (abiotic factors) in the ecosystem. Through biogeochemical cycles, water and other chemical elements are constantly being passed through living organisms to non-living matter and back again, over and over. Three important biogeochemical cycles are the water cycle, carbon cycle, and nitrogen cycle. The biogeochemical cycle that recycles water is the water cycle. The water cycle involves a series of interconnected pathways involving both the biotic and abiotic components of the biosphere. Water is obviously an extremely important aspect of every ecosystem. Life cannot exist without water. Many organisms contain a large amount of water in their bodies, and many live in water, so the water cycle is essential to life on earth. Water continuously moves between living organisms, such as plants, and non-living things, such as clouds, rivers, and oceans (Figure 10.1). The water cycle does not have a real starting or ending point. It is an endless recycling process that involves the oceans, lakes and other bodies of water, as well as the land surfaces and the atmosphere. The steps in the water cycle are as follows, starting with the water in the oceans: 1. Water evaporates from the surface of the oceans, leaving behind salts. As the water vapor rises, it collects and is stored in clouds. 2. As water cools in the clouds, condensation occurs. Condensation is when gases turn back into liquids. 3. Condensation creates precipitation. Precipitation includes rain, snow, hail, and sleet. The precipitation allows the water to return again to the Earth’s surface. 4. When precipitation lands on land, the water can sink into the ground to become part of our underground water reserves, also known as groundwater. Much of this underground water is stored in aquifers, which are porous layers of rock that can hold water.
Run-off
Most precipitation that occurs over land, however, is not absorbed by the soil and is called runoff. This runoff collects in streams and rivers and eventually flows back into the ocean.
Transpiration
Water also moves through the living organisms in an ecosystem. Plants soak up large amounts of water through their roots. The water then moves up the plant and evaporates from the leaves in a process called transpiration. The process of transpiration, like evaporation, returns water back into the atmosphere. Vocabulary
• • • • • • • • • •
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aquifer: Underground layer of rock that stores water. biogeochemical cycles: Process through which water or a chemical element is continuously recycled. carbon cycle: Pathways through which carbon is recycled through the biosphere. condensation: Process in which water vapor changes to tiny droplets of liquid water. groundwater: Underground water reserves. nitrogen cycle: Pathways through which nitrogen is recycled through the biosphere. precipitation: Water that falls from clouds in the atmosphere to Earth’s surface, such as rain, snow, and sleet. runoff: Precipitation that is not absorbed by the soil and flows over the surface of the ground. transpiration: Process in which plants give off water vapor. water cycle: Interconnected pathways through which water is recycled through the biotic and abiotic components of the biosphere.
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Chapter 10. The Water Cycle
FIGURE 10.1 The water cycle.
Summary
• Chemical elements and water are constantly recycled in the ecosystem through biogeochemical cycles. • During the water cycle, water enters the atmosphere by evaporation and transpiration, and water returns to land by precipitation. Practice
Use the resource below to answer the questions that follow. • The Water Cycle at http://www.youtube.com/watch?v=IncMhop-4Jc (2:48)
MEDIA Click image to the left for more content.
1. What is a fundamental difference between the water cycle and other nutrient cycles? 2. What drives the water cycle? Where does this process primarily occur? 3. What happens to most of the water taken up by plants? How does this compare to most of the water taken up by animals? 4. How does water’s role in photosynthesis explain increased biological productivity in areas of heavy precipitation? Review
1. What is the water cycle? 29
www.ck12.org 2. What are two ways water returns to the atmosphere? 3. How does water get from the atmosphere back to land?
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C HAPTER
Chapter 11. The Carbon Cycle
11
The Carbon Cycle
• Describe the key features of the carbon cycle. • Describe the relationship between photosynthesis and cellular respiration. • Define fossil fuels.
Why is Earth getting warmer? What happens if carbon is not removed from the atmosphere? The excess carbon dioxide in the atmosphere is contributing to a global rise in Earth’s temperature, known as global warming. Where does this carbon dioxide come from? Burning gas to power our cars and burning coal to generate electricity are two main sources of the excess carbon dioxide. The Carbon Cycle
Carbon is one of the most common elements found in living organisms. Chains of carbon molecules form the backbones of many molecules, such as carbohydrates, proteins, and lipids. Carbon is constantly cycling between living organisms and the atmosphere (Figure 11.1). The cycling of carbon occurs through the carbon cycle. Living organisms cannot make their own carbon, so how is carbon incorporated into living organisms? In the atmosphere, carbon is in the form of carbon dioxide gas (CO2 ). Recall that plants and other producers capture the 31
www.ck12.org carbon dioxide and convert it to glucose (C6 H12 O6 ) through the process of photosynthesis. Then as animals eat plants or other animals, they gain the carbon from those organisms. The chemical equation of photosynthesis is 6CO2 + 6H2 O → C6 H12 O6 + 6O2 . How does this carbon in living things end up back in the atmosphere? Remember that we breathe out carbon dioxide. This carbon dioxide is generated through the process of cellular respiration, which has the reverse chemical reaction as photosynthesis. That means when our cells burn food (glucose) for energy, carbon dioxide is released. We, like all animals, exhale this carbon dioxide and return it back to the atmosphere. Also, carbon is released to the atmosphere as an organism dies and decomposes. Cellular respiration and photosynthesis can be described as a cycle, as one uses carbon dioxide (and water) and makes oxygen (and glucose), and the other uses oxygen (and glucose) and makes carbon dioxide (and water).
FIGURE 11.1 The carbon cycle. The cycling of carbon dioxide in photosynthesis and cellular respiration are main components of the carbon cycle. Carbon is also returned to the atmosphere by the burning of fossil fuels and decomposition of organic matter.
Formation of Fossil Fuels
Millions of years ago, there were so many dead plants and animals that they could not completely decompose before they were buried. They were covered over by soil or sand, tar or ice. These dead plants and animals are organic matter made out of cells full of carbon-containing organic compounds (carbohydrates, lipids, proteins and nucleic acids). What happened to all this carbon? When organic matter is under pressure for millions of years, it forms fossil fuels. Fossil fuels are coal, oil, and natural gas. When humans dig up and use fossil fuels, we have an impact on the carbon cycle (Figure 11.2). This carbon is not recycled until it is used by humans. The burning of fossil fuels releases more carbon dioxide into the atmosphere than is used by photosynthesis. So, there is more carbon dioxide entering the atmosphere than is coming out of it. Carbon dioxide is known as a greenhouse gas, since it lets in light energy but does not let heat escape, much like the panes of a greenhouse. The increase of greenhouse gasses in the atmosphere is contributing to a global rise in Earth’s temperature, known as global warming. 32
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Chapter 11. The Carbon Cycle
FIGURE 11.2 Human activities like burning gasoline in cars are contributing to a global change in our climate.
Vocabulary
• carbon cycle: Pathways through which carbon is recycled through the biosphere. • cellular respiration: Process of breaking down glucose to obtain energy in the form of ATP. • fossil fuel: Remains of long-dead organisms that now serves as an energy source, such as as oil, coal, or natural gas. • global warming: Global rise in Earth’s temperature due to increases of greenhouse gasses in the atmosphere. • greenhouse gas: Gas that lets in light energy but does not let heat escape, contributing to global warming. • photosynthesis: Process by which specific organisms (including all plants) use the sun’s energy to make their own food from carbon dioxide and water; process that converts the energy of the sun, or solar energy, into carbohydrates, a type of chemical energy. Summary
• During the carbon cycle, animals and plants add carbon dioxide to the atmosphere through cellular respiration, and plants remove carbon dioxide through photosynthesis. • The burning of fossil fuels releases more carbon dioxide into the atmosphere, contributing to global warming. Practice
Use the resource below to answer the questions that follow. • Organic Carbon and the World Around Us from USGS http://gallery.usgs.gov/videos/571#.UKWjAId9 KSo (7:13)
MEDIA Click image to the left for more content.
1. What are two types of carbon? What type is carbon dioxide (CO2 )? What is an example of the other type? 33
www.ck12.org 2. How can carbon aid the spread of toxic substances? 3. Why are the reactivity and binding capabilities of carbon crucial to life? 4. Why is monitoring the levels and the forms of carbon in streams important to maintaining safe drinking water? Review
1. What biological process releases carbon back into the atmosphere? 2. What human activities have thrown the carbon cycle off balance?
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C HAPTER
Chapter 12. Ecosystems
12
Ecosystems
• Define and describe an ecosystem.
What nonliving things are essential for life? Living organisms cannot exist without the nonliving aspects of the environment. For example: air, water, and sunlight, which are all nonliving, are all essential to living organisms. Both nonliving and living things make up an ecosystem. What is an Ecosystem?
Ecology is the study of ecosystems. That is, ecology is the study of how living organisms interact with each other and with the nonliving part of their environment. An ecosystem consists of all the nonliving factors and living organisms interacting in the same habitat. Recall that living organisms are biotic factors. The biotic factors of an ecosystem include all the populations in a habitat, such as all the species of plants, animals, and fungi, as well as all the micro-organisms. Also recall that the nonliving factors are called abiotic factors. Abiotic factors include temperature, water, soil, and air. You can find an ecosystem in a large body of freshwater or in a small aquarium. You can find an ecosystem in a large thriving forest or in a small piece of dead wood. Examples of ecosystems are as diverse as the rainforest, the savanna, the tundra, or the desert (Figure 12.1). The differences in the abiotic factors, such as differences in temperature, rainfall, and soil quality, found in these areas greatly contribute to the differences seen in these ecosystems. Ecosystems can include well known sites, such as the Great Barrier Reef off the coast of Australia and the Greater Yellowstone Ecosystem of Yellowstone National Park, which actually includes a few different ecosystems, some with geothermal features, such as Old Faithful geyser. Ecosystems need energy. Many ecosystems get their energy in the form of sunlight, which enters the ecosystem through photosynthesis. This energy then flows through the ecosystem, passed from producers to consumers. Matter is also recycled in ecosystems. Biogeochemical cycles recycle nutrients, like carbon and nitrogen, so they are always available. These nutrients are used over and over again by organisms. Water is also continuously recycled. The flow of energy and the recycling of nutrients and water are examples of the interactions between organisms and the interactions between the biotic and abiotic factors of an ecosystem. 35
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FIGURE 12.1 An example of a desert ecosystem in Baja California, showing Saguaro cacti.
Vocabulary
• abiotic factor: Nonliving aspect of the environment. • biogeochemical cycle: Pathway of elements like carbon and nitrogen through the non-living and living parts of the ecosystem. • biotic factor: Living aspects of the environment. • consumer: Organism that must eat or consume other organisms to obtain energy and nutrients. • ecology: Study of how living organisms interact with each other and with their environment. • ecosystem: All of the living things and non-living things interacting in the same area. • habitat: Ecological or environmental area where a particular species live. • photosynthesis: Process by which specific organisms (including all plants) use the sun’s energy to make their own food from carbon dioxide and water; process that converts the energy of the sun, or solar energy, into carbohydrates, a type of chemical energy. • population: Group of organisms belonging to the same species that live in the same area and interact with one another. 36
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Chapter 12. Ecosystems
• producer: Organism that can absorb the energy of the sun and convert it into food through the process of photosynthesis; i.e. plants and algae. Summary
• An ecosystem consists of all the living things and nonliving things interacting in the same area. • Matter is also recycled in ecosystems; recycling of nutrients is important so they can always be available Practice
Use the resource below to answer the questions that follow. • How Ecosystems Work at http://www.youtube.com/watch?v=o_RBHfjZsUQ (3:24)
MEDIA Click image to the left for more content.
1. How do land plants generate the energy they need for their metabolic energy? What do they do with excess energy? Where does this energy go? 2. Where do scavengers in an ecosystem obtain their energy from? How can scavenging be a beneficial strategy for an organism? 3. Given that some areas at high latitudes go days or months without sunlight, how applicable do you think is the statement that light is never a limiting resource? Explain your thinking fully. 4. What do you think the relationship is between the total mass of carbon in a system and the total amount of biomass which can be generated in the ecosystem? What kind of problems can you foresee if every speck of carbon were turned into biomass? How long do you think a system like this would be stable? Explain your thinking. Review
1. Define an ecosystem. 2. Distinguish between abiotic and biotic factors.
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C HAPTER
13
Habitat and Niche
• Define habitat and niche and describe their role in the ecosystem.
What is your niche at school? Are you on the basketball team? Are you a cheerleader? Do you play an instrument in the band? Your niche would be your role or place in the school. Organisms also each have their own niche in the ecosystem. Is an organism a 38
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Chapter 13. Habitat and Niche
producer or a consumer? How does the organism interact with other organisms? Is the organism involved in any symbiotic relationships? Habitat and Niche Niche
Each organism plays a particular role in its ecosystem. A niche is the role a species plays in the ecosystem. In other words, a niche is how an organism “makes a living.” A niche will include the organism’s role in the flow of energy through the ecosystem. This involves how the organism gets its energy, which usually has to do with what an organism eats, and how the organism passes that energy through the ecosystem, which has to do with what eats the organism. An organism’s niche also includes how the organism interacts with other organisms, and its role in recycling nutrients. Once a niche is left vacant, other organisms can fill that position. For example when the Tarpan, a small wild horse found mainly in southern Russia, became extinct in the early 1900s, its niche was filled by a small horse breed, the Konik (Figure 13.1).
FIGURE 13.1 The Konik horse.
This horse filled the
niche left by the Tarpan, a horse that became extinct in the early 1900s in southern Russia.
A species’ niche must be specific to that species; no two species can fill the same niche. They can have very similar niches, which can overlap, but there must be distinct differences between any two niches. When plants and animals are introduced, either intentionally or by accident, into a new environment, they can occupy the existing niches of native organisms. Sometimes new species out-compete native species, and the native species may go extinct. They can then become a serious pest. For example, kudzu, a Japanese vine, was planted in the southeastern United States in the 1870s to help control soil loss. Kudzu had no natural predators, so it was able to out-compete native species of vine and take over their niches (Figure 13.2). Habitat
The habitat is the physical area where a species lives. Many factors are used to describe a habitat. The average amount of sunlight received each day, the range of annual temperatures, and average yearly rainfall can all describe a habitat. These and other abiotic factors will affect the kind of traits an organism must have in order to survive there. A habitat should not be confused with an ecosystem: the habitat is the actual place of the ecosystem, whereas the ecosystem includes both the biotic and abiotic factors in the habitat. 39
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FIGURE 13.2 Kudzu, a Japanese vine, introduced intentionally to the southeastern United States, has out-competed the native vegetation.
FIGURE 13.3 Santa Cruz Island off the California coast has diverse habitats including a coastline with steep cliffs, coves, gigantic caves, and sandy beaches.
Habitat destruction means what it sounds like—an organism’s habitat is destroyed. Habitat destruction can cause a population to decrease. If bad enough, it can also cause species to go extinct. Clearing large areas of land for housing developments or businesses can cause habitat destruction. Poor fire management, pest and weed invasion, and storm damage can also destroy habitats. National parks, nature reserves, and other protected areas all preserve habitats.
Vocabulary
• abiotic factor: Aspect of the environment that is not a living organism, such as soil, water, or air. • biotic factor: Components of the environment that are living, or were alive and then died, such as plants or animals. • habitat : Natural home or environment of an organism; the physical environment in which a species lives. 40
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Chapter 13. Habitat and Niche
FIGURE 13.4 The above image shows wetland reeds, another type of habitat.
• niche: Role a species plays in the ecosystem.
Summary
• The role a species plays in the ecosystem is called its niche. • A habitat is the physical environment in which a species lives.
Practice
Use the resource below to answer the questions that follow. • Competition, Predation, Symbiosis at http://www.youtube.com/watch?v=D1aRSeT-mQE (3:20)
MEDIA Click image to the left for more content.
1. Niches and relationships between organisms are generally developed over a long period of time. How do you think rapid changes in the chracteristics of niches affect the animals occupying that niche? 2. Do you think rapid or gradual changes in niches have a greater potential to affect organisms? Think carefully and realize there may not be only one answer. 3. On a very broad scale, how are the niches of a carnivore and an herbivore in the same geographic area similar? How do they differ? 41
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1. What is a niche? 2. Name three factors that can be used to describe a habitat.
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C HAPTER
Chapter 14. Bird Ecology
14
Bird Ecology
• Summarize the diversity of bird habitats and food sources.
Where do birds live? Practically anywhere they want. From some of the coldest regions on the planet to the warmest. Look at these penguins. Would you want to live there?
Ecology of Birds
Birds live and breed in most terrestrial habitats on all seven continents, from the Arctic to Antarctica. Because they are endothermic, birds can live in a wider range of climates than reptiles or amphibians, although the greatest diversity of birds occurs in tropical regions. Birds are important members of every ecosystem in which they live, occupying a wide range of ecological positions.
Bird Diets
Some birds are generalists. A generalist is an organism that can eat many different types of food. Other birds are highly specialized in their food needs and can eat just one type of food. Raptors such as hawks and owls are carnivores. They hunt and eat mammals and other birds. Vultures are scavengers. They eat the remains of dead animals, such as roadkill. Aquatic birds generally eat fish or water plants. Perching birds may eat insects, fruit, honey, or nectar. Many fruit-eating birds play a key role in seed dispersal, and some nectar-feeding birds are important pollinators. Bird beaks are generally adapted for the food they eat. For example, the sharp, hooked beak of a raptor is well suited for killing and tearing apart prey. The long beak of the hummingbird in Figure 14.1 co-evolved with the tube-shaped flowers from which it sips nectar. 43
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FIGURE 14.1 Hummingbird Sipping Nectar.
A hum-
mingbird gets nectar from flowers and pollinates the flowers in return. What type of relationship exists between the bird and the flowering plant?
Birds at Risk
Hundreds of species of birds have gone extinct as a result of human actions. A well-known example is the passenger pigeon. It was once the most common bird in North America, but overhunting and habitat destruction led to its extinction in the 1800s. Habitat destruction and use of the pesticide DDT explain the recent extinction of the dusky seaside sparrow. This native Florida bird was declared extinct in 1990. Today, some 1,200 species of birds are threatened with extinction by human actions. Humans need to take steps to protect this precious and important natural resource. What can you do to help?
The Golden Eagle
Although not as famous as its bald cousin, Golden Eagles are much easier to find in Northern California - one of the largest breeding populations for Golden Eagles. The largest of the raptors, Golden Eagles weigh typically between 8 and 12 pounds, and their wing span is around 6 to 7 feet. These eagles dive towards earth to catch prey, and can reach speeds of up to 200 mph! Meet one of the largest birds of prey at http://www.kqed.org/quest/television/cool-cr itters-the-golden-eagle.
MEDIA Click image to the left for more content.
The Great Horned Owl
Owls are amazing creatures. They have many adaptations that allow them to thrive in their environments. Their claws are enormous and powerful, they have excellent hearing, and fantastic vision in low light. And the Great Horned Owl can fly almost silently due to "fringes" on their feathers that help to break up the sound of air passing 44
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Chapter 14. Bird Ecology
over their wings. Learn more of the Great Horned Owl at http://www.kqed.org/quest/television/cool-critters-great -horned-owls-.
MEDIA Click image to the left for more content.
Summary
• Birds live and breed in most terrestrial habitats on all seven continents. They occupy a wide range of ecological positions. • Raptors are carnivores; aquatic birds eat fish or water plants; and perching birds may eat insects, fruit, honey, or nectar. • Some birds are pollinators that co-evolved with plants. • Human actions have caused the extinction of hundreds of species of birds, and some 1,200 species are threatened with extinction today. Practice I
Use these resources to answer the questions that follow. • Avian Ecology at http://www.paulnoll.com/Oregon/Birds/Avian-ecology.html and Bird Ecosystems at http ://www.paulnoll.com/Oregon/Birds/ecology-ecosystems.html. 1. 2. 3. 4. 5.
To a bird, what is its nest? How do birds decorate their nests? Give examples of places birds live. What is the ecosystem of the Red-Cockaded Woodpecker and the Greater Prairie-Chicken? What is a generalist?
Practice II
• Pick the Pollinator at http://www.pbs.org/wgbh/nova/nature/pollination-game.html. Review
1. Draw a sketch of a hypothetical bird that preys on small mammals. The bird must exhibit traits that suit it for its predatory role. 2. Why did the hummingbird pictured sipping nectar above evolve such a long, pointed beak?
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C HAPTER
15 Nonrenewable Resources
• Describe nonrenewable resources.
Could we all run out of gasoline? Yes, we will use up all our gasoline eventually. Gasoline is derived from oil. Oil deposits were formed over hundreds of millions of years. They cannot be quickly replenished. Oil is an example of a nonrenewable resource. Nonrenewable Resources
A nonrenewable resource is a natural resource that is consumed or used up faster than it can be made by nature. Two main types of nonrenewable resources are fossil fuels and nuclear power. Fossil fuels, such as petroleum, coal, and natural gas, formed from plant and animal remains over periods from 50 to 350 million years ago. They took millions of years to form. Humans have been consuming fossil fuels for less than 200 years, yet remaining reserves of oil can supply our needs only until around the year 2055. Natural gas can only supply us until around 2085. Coal will last longer, until around the year 2250. That is why it is so important to develop alternate forms of energy, especially for our cars. Today, electric cars are becoming more and more common. What would happen if we ran out of gasoline? Alternative use of energy, especially in transportation, must become a standard feature of all cars and trucks and planes by the middle of the century. Nuclear power is the use of nuclear energy (nuclear fission) to create energy inside of a nuclear reactor (Figure 15.1). Nuclear power is developed from atoms in certain elements, such as uranium. Currently, there are limited uranium fuel supplies, which will last to about the year 2100 (or longer) at current rates of use. However, new technologies could make some uranium fuel reserves more useful. Population growth, especially in developing countries, should make people think about how fast they are consuming resources. Governments around the world should seriously consider these issues. Developing nations will also increase demands on natural resources as they build more factories (Figure 15.2). Improvements in technology, conservation of resources, and controls in population growth could all help to decrease the demand on natural resources. 46
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Chapter 15. Nonrenewable Resources
FIGURE 15.1 Aerial photo of the Bruce Nuclear Generating Station near Kincardine, Ontario.
FIGURE 15.2 Per capita energy consumption (2003) shows the unequal distribution of wealth, technology, and energy use.
Vocabulary
• fossil fuels: Remains of long-dead organisms that now serve as an energy source, such as as oil, coal, or natural gas. 47
www.ck12.org • nonrenewable resource: Natural resource that is used up faster than it can be made by nature. • nuclear fission: Nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, often producing free neutrons and photons in the form of gamma rays, and releasing a very large amount of energy. • nuclear power: Electricity generated through the use nuclear energy (fission) inside a nuclear reactor. Summary
• Nonrenewable resources are being used up faster than they can be made by nature. • Nonrenewable resources include fossil fuels and nuclear power. Practice
Use the resource below to answer the questions that follow. • Formation of Fossil Fuels at http://www.youtube.com/watch?v=_8VqWKZIPrM (2:26)
MEDIA Click image to the left for more content.
1. 2. 3. 4.
How does the formation of coal differ from the formation of oil? How are these processes the same? Why are researchers looking for ways to speed up the production of fuel from plant matter? Where does natural gas come from? When you burn fossils fuels, they release C02 into the atmosphere. Based on how long it takes fossil fuels to form, when was the last time that the carbon molecule in the C02 was in the atmosphere? How does this situation differ from someone cutting down a ten-year-old tree and burning it in his/her fireplace?
Review
1. How were fossil fuels created? 2. Why is nuclear power considered a nonrenewable resource?
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C HAPTER
Chapter 16. Habitat Destruction
16
Habitat Destruction
• Discuss what causes the destruction of habitats.
What’s happening to this land? This picture, taken in southern Mexico, shows land being cleared for agriculture. The forest has been cut down and burned to make room for a a farm. In the process, homes to many plants and animals were destroyed. This is an example of habitat destruction. Habitat Destruction
From a human point of view, a habitat is where you live, go to school, and go to have fun. Your habitat can be altered, and you can easily adapt. Most people live in a few different places and go to a number of different schools throughout their life. But a plant or animal may not be able to adapt to a changed habitat. A habitat is the natural home or environment of an organism. Humans often destroy the habitats of other organisms. Habitat destruction can cause the extinction of species. Extinction is the complete disappearance of a species. Once a species is extinct, it can never recover. Some ways humans cause habitat destruction are by clearing land and by introducing non-native species of plants and animals. Land Loss
Clearing land for agriculture and development is a major cause of habitat destruction. Within the past 100 years, the amount of total land used for agriculture has almost doubled. Land used for grazing cattle has more than doubled. Agriculture alone has cost the United States half of its wetlands (Figure 16.1) and almost all of its tallgrass prairies (Figure 16.2). Native prairie ecosystems, with their thick fertile soils, deep-rooted grasses, diversity of colorful flowers, burrowing prairie dogs, and herds of bison and other animals, have virtually disappeared (Figure 16.3). 49
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FIGURE 16.1 Wetlands such as this one in Cape May, New Jersey, filter water and protect coastal lands from storms and floods.
FIGURE 16.2 Big bluestem grasses as tall as a human were one of the species of the tallgrass prairie, largely destroyed by agricultural use.
Slash-and-Burn Agriculture
Other habitats that are being rapidly destroyed are forests, especially tropical rainforests. The largest cause of deforestation today is slash-and-burn agriculture (shown in the opening image). This means that when people want to turn a forest into a farm, they cut down all of the trees and then burn the remainder of the forest. This technique is used by over 200 million people in tropical forests throughout the world. As a consequence of slash-and-burn agriculture, nutrients are quickly lost from the soil. This often results in people abandoning the land within a few years. Then the top soil erodes and desertification can follow. Desertification turns forest into a desert, where it is difficult for plants to grow. Half of the Earth’s mature tropical forests are gone. At current rates of deforestation, all tropical forests will be gone by the year 2090. 50
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Chapter 16. Habitat Destruction
FIGURE 16.3 Herds of bison also made up part of the tallgrass prairie community.
Non-native Species
One of the main causes of extinction is introduction of exotic species into an environment. These exotic and new species can also be called invasive species or non-native species. These non-native species, being new to an area, may not have natural predators in the new habitat, which allows their populations to easily adapt and grow. Invasive species out-compete the native species for resources. Sometimes invasive species are so successful at living in a certain habitat that the native species go extinct (Figure 16.4). Recently, cargo ships have transported zebra mussels, spiny waterfleas, and ruffe (a freshwater fish) into the Great Lakes (Figure 16.5). These invasive species are better at hunting for food. They have caused some of the native species to go extinct. Invasive species can disrupt food chains, carry disease, prey on native species directly, and out-compete native species for limited resources, like food. All of these effects can lead to extinction of the native species.
FIGURE 16.4 An exotic species, the brown tree snake, hitchhiked on an aircraft to the Pacific Islands, causing the extinctions of many bird and mammal species which had evolved in the absence of predators.
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FIGURE 16.5 These
zebra
mussels,
an
invasive
species, live on most man-made and natural surfaces. Here they have infested the walls of the Arthur V. Ormond Lock on the Arkansas River.
They have
caused significant damage to American waterways, locks, and power plants.
Other Causes
Other causes of habitat destruction include poor fire management, overfishing, mining (Figure 16.6), pollution, and storm damage. All of these can cause irreversible changes to a habitat and ecosystem.
FIGURE 16.6 Strip coal mining, pictured here, has destroyed the entire ecosystem.
Examples of Habitat Destruction
A habitat that is quickly being destroyed is the wetland. By the 1980s, over 80% of all wetlands in parts of the U.S. were destroyed. In Europe, many wetland species have gone extinct. For example, many bogs in Scotland have been lost because of human development. Another example of species loss due to habitat destruction happened on Madagascar’s central highland plateau. From 1970 to 2000, slash-and-burn agriculture destroyed about 10% of the country’s total native plants. The area 52
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Chapter 16. Habitat Destruction
turned into a wasteland. Soil from erosion entered the waterways. Much of the river ecosystems of several large rivers were also destroyed. Several fish species are almost extinct. Also, some coral reef formations in the Indian Ocean are completely lost.
Vocabulary
• bog: Wetland that accumulates peat, a deposit of dead plant material, often mosses; one of the four main types of wetlands. • desertification: Process by which fertile land is depleted of top soil and becomes a desert. • extinction: Complete disappearance of a species. • habitat: Natural home or environment of an organism; the physical environment in which a species lives. • invasive species: Exotic, introduced species that out-competes the native species. • non-native species: Exotic species introduced into a new habitat. • slash-and-burn agriculture: Clearing of land for agriculture by cutting down and burning forest. • wetland: Land area that is saturated with water, either permanently or seasonally, with the characteristics of a distinct ecosystem.
Summary
• There are many causes of habitat destruction, including clearing of land and introduction of invasive species. • Slash-and-burn agriculture can lead to desertification, meaning the fertile top soil is lost.
Practice
Use the resource below to answer the questions that follow. • Suburban Growth Stresses Streams at http://www.youtube.com/watch?v=54k5vaWIRdA
MEDIA Click image to the left for more content.
1. How does the loss of trees along streams affect steam ecosystems? How are aquatic plants affected? How does this situation alter the food web in streams? 2. Loss of trees has destabilized some stream banks. How are aquatic insects affected by this situation? What has this done for water clarity? How may this affect photosynthesis in streams? How does this situation affect food webs in streams? 3. How have urban areas affected the diversity of fish in streams? What types of fish are being selected for? • The Ecology of Climate Change at http://www.youtube.com/watch?v=isPGjChdby8 (8:07)
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MEDIA Click image to the left for more content.
1. What types of trees dominate boreal forests? 2. How is climate change affecting the amount of fires occurring in Alaska? How is this affecting the ecosystem? 3. How do conifer forests differ from deciduous forest in their effect on temperature? How may this feed into climate change? 4. How may the thawing of permafrost affect the Global Carbon Cycle? How much carbon is locked up in permafrost? How is the carbon in the permafrost similar to the carbon in fossil fuel? 5. How do current models of climate change account for the carbon in permafrost? Review
1. What are the primary ways that humans destroy habitats? 2. Describe slash-and-burn agriculture.
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C HAPTER
Chapter 17. Importance of Biodiversity
17Importance of Biodiversity
• Define biodiversity and describe its importance.
Why is preserving the rainforest important? Preserving the rainforest is important for many reasons. But one reason conservation efforts have focused here is that the rainforest is home to more species of insects, amphibians, and birds than anywhere else on the planet. This wide diversity of life is called biodiversity. Importance of Biodiversity
Biodiversity is a measurement of the amount of variation of the species in a given area. More specifically, biodiversity can be defined as the variety of life and its processes, including the variety of living organisms, the genetic differences among them, and the communities and ecosystems in which they occur. A place such as a coral reef has many different species of plants and animals. That means the coral reef is a ecosystem with high biodiversity (Figure 17.1). Because of its biodiversity, the rainforest shown above is an ecosystem with extreme importance. Why is biodiversity so important? In addition to maintaining the health and stability of the ecosystem, the diversity of life provides us with many benefits. Extinction is a threat to biodiversity. Does it matter if we are losing thousands of species each year? The answer is yes. It matters even if we consider not only the direct benefits to humans, but also the benefits to the ecosystems. The health and survival of ecosystems is related to that ecosystem’s biodiversity. Economic Importance
Economically, there are many direct benefits of biodiversity. As many as 40,000 species of fungi, plants, and animals provide us with many varied types of clothing, shelter, medicines and other products. These include poisons, timber, 55
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FIGURE 17.1 Coral reefs are one of the biomes with the highest biodiversity on earth.
fibers, fragrances, papers, silks, dyes, adhesives, rubber, resins, skins, furs, and more. According to one survey, 57% of the most important prescription drugs come from nature. Specifically, they come from bacteria, fungi, plants, and animals (Figure 17.2). But only a small amount of species with the ability to give us medicines have been explored. The loss of any species may mean the loss of new medicines, which will have a direct effect on human health.
FIGURE 17.2 Aspirin originally came from the bark of the white willow tree, pictured here.
Biodiversity and Technology
Nature has inspired many technologies in use today. Bionics, also known as biomimetics or biomimicry, uses organisms to inspire technology or engineering projects. By studying animals and their traits, we are able to gain valuable information that we can put to use to help us. For example, rattlesnake heat-sensing pits helped inspire the development of infrared sensors. Zimbabwe’s Eastgate Centre (Figure 17.3) was inspired by the air-conditioning efficiency of a termite mound (Figure 17.4). 56
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Chapter 17. Importance of Biodiversity
FIGURE 17.3 Design of the Eastgate Centre (brown building), in Zimbabwe, which requires just 10% of the energy needed for a conventional building of the same size, was inspired by a biological design.
FIGURE 17.4 The air-conditioning efficiency of this termite mound was the inspiration for the Eastgate Centre.
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www.ck12.org Ecological Importance
Biodiversity also has many benefits to ecosystems. High biodiversity makes ecosystems more stable. What can happen to an ecosystem if just one species goes extinct? What if that one species was a producer or decomposer? Maybe the resulting species will adapt. Other species may fill in the niche left by the extinct species. But the extinction of one species could have a "domino" effect, resulting in the extinction of other species. This could greatly effect the stability of the whole ecosystem. One important role of biodiversity is that it helps keep the nutrients, such as nitrogen, in the soil. For example, a diversity of organisms in the soil allows nitrogen fixation and nutrient recycling to happen. Biodiversity also allows plants to be pollinated by different types of insects. And of course, different species of fungi are necessary to recycle wastes from dead plants and animals. These are just a few of the many examples of how biodiversity is important for ecosystems. Vocabulary
• biodiversity: Measurement of the amount of variation of the species in a given area. • bionics: Use of organisms to inspire technology or engineering projects. • decomposer: Organism that obtains nutrients and energy by breaking down dead organisms and animal wastes. • extinction: Dying out of a species so that no members of the species exist anymore. • niche: Role a species plays in the ecosystem. • nitrogen fixation: Process of converting nitrogen gas in the air into nitrates in the soil. • producer: Organism that produces food (glucose) for itself and other organisms. Summary
• Biodiversity is a measurement of the amount of variation of the species in a given area. • Biodiversity is important because it directly benefits humans and ecosystems. Practice
Use the resource below to answer the questions that follow. • In Search of Wild Variety from American Museum of Natural History http://www.youtube.com/watch?v=P bg_pGZv3CQ (1:52)
MEDIA Click image to the left for more content.
1. To date, how many species have been identified on the Earth? How close do scientist feel this number is to the total number of species which exist? 2. In what kinds of locations are new species being found? What does this situation say about the total number of species which may exist? 3. Can different species be identified by just looking at them? What techniques are scientists using to identify new species? 58
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Chapter 17. Importance of Biodiversity
Review
1. What does it mean if a place has high biodiversity? 2. What is an economic impact of biodiversity?
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