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•Preview Section 1: What Is an Ecosystem? • • • • • • • • Bellringer Key Ideas Ecosystems Succession Major Biological Communities Terrestrial Biomes Aquatic Ecosystems Summary •After Bellringer looking at an aquarium, list all the organisms you see. When you are finished make a list of all the factors that affect the survival of the organisms in the aquarium. • Key Ideas • What are the parts of an ecosystem? • How does an ecosystem respond to change? • What two key factors of climate determine a biome? • What are the three major groups of terrestrial biomes? • What are the four kinds of aquatic ecosystems? • • • Ecosystems A group of various species that live in the same place and interact with one another is called a community. The group, along with the living and nonliving environment, make up an ecosystem. • An ecosystem includes a community of organisms and their physical environment. • Ecosystems, continued • • • • • • • • A community of organisms is a web of relationships. Relationships between organisms are examples of biotic factors that affect an ecosystem. Biotic describes living factors in an ecosystem. The physical or nonliving factors of an environment are called abiotic factors. Examples of abiotic factors are oxygen, water, rocks, sand, sunlight, temperature, and climate. A habitat is the place where an organism lives. Visual Concept: Comparing Biotic and Abiotic Factors Ecosystems, continued The variety of organisms in a given area is called biodiversity. Physical factors can have a big influence on biodiversity. High or low temperatures, or limited food or water can lower biodiversity. • Ecosystems with high biodiversity are often more able to resist damage. • Ecosystems, continued • • • Damage to ecosystems can be caused by severe weather events or human activities. Systems with low biodiversity can be severely damaged easily. When biodiversity decreases in any ecosystem, that ecosystem is not as healthy as it could be. Succession • • • • • • • • • • • • • • The replacement of one kind of community by another at a single place over a period of time is called succession. The first organisms to appear in a newly made habitat are often called pioneer species. They change the habitat in such a way that other species can live in the ecosystem. Often, the new species will replace the pioneer species. Visual Concept: Pioneer Species Succession, continued An ecosystem responds to change in such a way that the ecosystem is restored to equilibrium. For example, when a tree falls down in a rain forest, the newly vacant patch proceeds through succession until the patch returns to its original state. Sometimes, the ecosystem will find an equilibrium in which different species dominate after a change. Ecological Succession at Glacier Bay Major Biological Communities The kinds of species that live in a particular place are determined partly by climate. Climate is the average weather conditions in an area over a long period of time. A biome is a large region characterized by a specific kind of climate and certain kinds of plant and animal communities. Major Biological Communities, continued Two key factors of climate that determine biomes are temperature and precipitation. • • • • Most organisms are adapted to live within a particular range of temperatures and cannot survive at temperatures too far above or below that range. Precipitation also determines the kinds of species that are found in a biome. Terrestrial Biomes Earth’s major terrestrial biomes can be grouped by latitude. Latitude affects the amount of solar energy that a biome receives and thus affects a biome’s temperature range. • Tropical biomes are generally near the equator. • For the most part, temperate biomes are between 30° and 60° latitude. • High-latitude biomes are at latitudes 60° and higher. • Earth’s Major biomes •Tropical Terrestrial Biomes, continued Biomes • • • • Because they are located at low latitudes near the equator, all tropical biomes are warm. Tropical rain forests receive large amounts of rain and are warm all year. They have the greatest biodiversity of any land biome. Savannas are tropical grasslands that have long dry seasons and shorter wet seasons. Tropical deserts get very little rain. Because deserts are drier, they have fewer plants and animals than other biomes. •Temperate Terrestrial Biomes, continued Biomes • Biomes at mid-latitudes have a wide range of temperatures throughout the year. • • • Temperate grasslands have moderate precipitation and cooler temperatures than savannas do. Temperate grasslands are often used for agriculture. Temperate forests grow in mild climates that receive plenty of rain. Temperate deserts receive little precipitation, but have a wide temperature range throughout the year. •High-Latitude Terrestrial Biomes, continued Biomes • • • • • • • • • • Biomes at high latitudes have cold temperatures. Coniferous forests in cold, wet climates are called taiga. Winters are long and cold. Most of the precipitation falls in the summer. The tundra gets very little rain, so plants are short. Much of the water in the soil is not available because the water is frozen for most of the year. Elements of Climate Aquatic Ecosystems Aquatic ecosystems are organized into freshwater ecosystems, wetlands, estuaries, and marine ecosystems. Freshwater ecosystems are located in bodies of fresh water, such as lakes, ponds, and rivers. These ecosystems have a variety of plants, fish, arthropods, mollusks, and other invertebrates. Wetlands provide a link between the land and fully aquatic habitats. Water-loving plants dominate wetlands. Wetlands moderate flooding and clean the water that flows through them. Aquatic Ecosystems, continued An estuary is an area where fresh water from a river mixes with salt water from an ocean. Estuaries are productive ecosystems because they constantly receive fresh nutrients from the river and the ocean. • • • • • • • • Marine ecosystems are found in the salty waters of the oceans. Kelp forests, seagrass communities, and coral reefs are found near land. The open ocean, far from land, has plankton and large predators, such as dolphins, whales, and sharks. Summary An ecosystem is a community of organisms and their abiotic environment. An ecosystem responds to change in such a way that the ecosystem is restored to equilibrium. Two key factors of climate that determine biomes are temperature and precipitation. Summary, continued Earth’s major terrestrial biomes can be grouped by latitude into tropical, temperate biomes, and high latitude. Aquatic ecosystems are organized into freshwater ecosystems, wetlands, estuaries, and marine ecosystems. •Preview Section 2: Energy Flow in Ecosystems • • • • • Bellringer Key Ideas Trophic Levels Loss of Energy Summary •ThinkBellringer about your local area and make a diagram of a food chain that would be typical for your area. Try to put six organisms into the food chain. • • • • • • • • Key Ideas How does energy flow through an ecosystem? What happens to energy as it is transferred between trophic levels in a community? Trophic Levels The primary source of energy for an ecosystem is the sun. Photosynthetic organisms, such as plants and algae, change light energy from the sun into energy that they can use to grow. These photosynthetic organisms are producers, the basic food source for an ecosystem. Consumers are organisms that eat other organisms instead of producing their own food. • • • • • • • Visual Concept: Comparing Consumers and Producers Trophic Levels, continued Decomposers, such as bacteria and fungi, are organisms that break down the remains of animals. In an ecosystem, energy flows from the sun to producers to consumers to decomposers. Each step in the transfer of energy through an ecosystem is called a trophic level. Trophic Levels Trophic Levels, continued Food Chains • • • • • • • • In ecosystems, energy flows from one trophic level to the next, forming a food chain. The first trophic level of ecosystems is made up of producers. Plants, algae, and some bacteria use the energy in sunlight to build energy-rich carbohydrates. The second trophic level of a food chain is made up of herbivores, which eat producers. Cows are an example of an herbivore. Trophic Levels, continued The third trophic level includes animals that eat herbivores. Any animal that eats another animal is a carnivore. Some carnivores are on the third trophic level because they eat herbivores. Other carnivores are on the fourth trophic level or an even higher trophic level because they eat other carnivores. Omnivores, such as bears, are animals that are both herbivores and carnivores. Visual Concept: Types of Consumers •FoodTrophic Levels, continued Webs • • • In most ecosystems, energy does not follow a simple food chain. Energy flow is much more complicated. Ecosystems almost always have many more species than a single food chain has. In addition, most organisms eat more than one kind of food. This complicated, interconnected group of food chains is called a food web. • Food Chain and Food Web in Antarctic Ecosystem •EnergyLossPyramid of Energy • • • • • • • Energy is stored at each link in a food web. But some energy that is used dissipates as heat into the environment and is not recycled. When an animal eats food, it gets energy from the food. When the energy is used, about 90% of it is converted into heat energy and is dispersed into the environment. Energy Transfer Through Trophic Levels Loss of Energy, continued Only about 10% is stored in the animal’s body as fat or as tissue. This amount of stored energy is all that is available to organisms at the next trophic level that consume the animal. An energy pyramid is a triangular diagram that shows an ecosystem’s loss of energy, which results as energy passes through the ecosystem’s food chain. • Each layer in the energy pyramid represents one trophic level. • Loss of Energy, continued • Producers form the pyramid’s base, which is the lowest trophic level. The lowest level has the most energy in the pyramid. • Herbivores have less energy and make up the second level. • Carnivores that feed on herbivores make up the higher level. • • • • • • • • • Visual Concept: Energy Pyramid Energy Loss, continued The energy stored by the organisms at each trophic level is about one tenth the energy stored by the organisms in the level below. So, the diagram takes the shape of a pyramid. Big predators, such as lions, are rare compared to herbivores. Big predators are rare because a lot more energy is required to support a single predator than a single herbivore. Many ecosystems do not have enough energy to support a large population of predators. Amount of Energy at Four Trophic Levels Summary In an ecosystem, energy flows from the sun to producers to consumers to decomposers. Energy is stored at each link in a food web, but some energy that is used dissipates as heat into the environment and is not recycled. •Preview Section 3: Cycling of Matter • • • • • • • Bellringer Key Ideas Water Cycle Carbon and Oxygen Cycles Nitrogen Cycle Phosphorus Cycle Summary •MakeBellringer a list of anything you have used in the last week that had been previously recycled, or was made of recycled materials. After you have made your list, discuss what the item is recycled from, if known, and the advantages or disadvantages of recycling each item. • Key Ideas • What is the water cycle? • Why are plants and animals important for carbon and oxygen in an ecosystem? • Why must nitrogen cycle through an ecosystem? • Why must phosphorus cycle through an ecosystem? • Water Cycle • The water cycle continuously moves water between the atmosphere, the land, and the oceans. • Water vapor condenses and falls to Earth’s surface as precipitation. • Some of this water percolates into the soil and becomes groundwater. • Water Cycle, continued • Other water runs across the surface of Earth into rivers, lakes, and oceans. • Then, the water is heated by the sun and reenters the atmosphere by evaporation. • Water also evaporates from trees and plants in a process called transpiration. • • • • • • • • • • • Visual Concept: Water Cycle Carbon and Oxygen Cycles Carbon and oxygen are critical for life on Earth, and their cycles are tied closely together. The carbon cycle is the continuous movement of carbon from the nonliving environment into living things and back. Animals, plants, and other photosynthesizing organisms play an important role in cycling carbon and oxygen through an ecosystem. Carbon and Oxygen Cycles, continued Plants use the carbon dioxide, CO2, in air to build organic molecules during the process of photosynthesis. During photosynthesis, oxygen is released into the surroundings. Many organisms, such as animals, use this oxygen to help break down organic molecules, which releases energy and CO2. Plants can use the CO2 in photosynthesis. Respiration is the process of exchanging oxygen and CO2 between organisms and their surroundings. Carbon and Oxygen Cycles, continued Carbon is also released into the atmosphere in the process of combustion. Combustion is the burning of a substance. • • • • • • • • • • • • • • Fossil fuels are formed from the remains of dead plants and animals, which are made of carbon. The burning of fossil fuels releases carbon dioxide into the atmosphere. Humans burn fossil fuels, such as oil and coal, to generate electricity and to power vehicles. Visual Concept: Carbon Cycle Nitrogen Cycle Nitrogen must be cycled through an ecosystem so that the nitrogen is available for organisms to make proteins. The nitrogen cycle is the process in which nitrogen circulates among the air, soil, water, and organisms in an ecosystem. The atmosphere is about 78% nitrogen gas, N2. But most organisms cannot use nitrogen gas. It must be changed into a different form. Nitrogen Cycle, continued In a process called nitrogen fixation, bacteria convert nitrogen gas, N2, into ammonia, NH3. Nitrogen-fixing bacteria live in the soil and on the roots of some plants. Nitrogen may also be fixed by lightning. Nitrogen is also fixed when humans burn fuels in vehicles and industrial plants. Nitrogen Cycle, continued Assimilation is the process in which plants absorb nitrogen. When an animal eats a plant, nitrogen compounds become part of the animal’s body. During ammonification, nitrogen from animal waste or decaying bodies is returned to the soil by bacteria. • • • • • • • • • During nitrification, ammonia, NH3, is converted to nitrite and then nitrate. During denitrification, nitrate, NO3, is changed to nitrogen gas, N2, which returns to the atmosphere. Visual Concept: Nitrogen Cycle Phosphorus Cycle Like water, carbon, oxygen, and nitrogen, phosphorus must be cycled in order for an ecosystem to support life. The phosphorus cycle is the movement of phosphorus in different chemical forms from the surroundings to organisms and then back to the surroundings. Phosphorus Cycle, continued Phosphorus is often found in soil and rock as calcium phosphate, which dissolves in water to form phosphate. The roots of plants absorb phosphate. Humans and animals that eat the plants reuse the organic phosphorus. • When the humans and animals die, phosphorus is returned to the soil. • Summary • • • • The water cycle is the continuous movement of water between the atmosphere, the land, and the oceans. Animals, plants, and other photosynthesizing organisms play an important role in cycling carbon and oxygen through an ecosystem. Nitrogen must be cycled through an ecosystem so that the nitrogen is available for organisms to make proteins. Like water, carbon, oxygen, and nitrogen, phosphorus must be cycled in order for an ecosystem to support life. Section 4: Populations Key Ideas • • • • Why is it important to study populations? What is the difference between exponential growth and logistic growth? What factors affect population size? How have science and technology affected human population growth? What Is a Population? • • • A population is made up of a group of organisms of the same species that live together in one place at one time and interbreed. Populations can be small or large. Some populations stay at nearly the same number for years at a time. Some populations die out from lack of resources. Other populations grow rapidly. Understanding population growth is important because populations of different species interact and affect one another, including human populations. Population Growth • Whether a population grows or shrinks depends on births, deaths, immigration, and emigration. • Immigration is the movement of individuals into a population. • Emigration is the movement of individuals out of a population. • A simple population model describes the rate of population growth as the difference between birthrate, death rate, immigration, and emigration. • • • • • • • • • • Plotting population changes against time on a graph creates a model in the form of a curve. Two major models of population growth are exponential growth and logistic growth. Exponential growth occurs when numbers increase by a certain factor in each successive time period. This type of increase causes the J-shaped curve of exponential growth. In exponential growth, population size grows slowly when it is small. But as the population gets larger, growth speeds up. Populations do not grow unchecked forever. Factors such as availability of food, predators, and disease limit the growth of a population. Eventually, population growth slows and may stabilize. An ecosystem can support only so many organisms. The largest population that an environment can support at any given time is called the carrying capacity. Density-dependent factors are variables affected by the number of organisms present in a given area. Density independent factors are variables that affect a population regardless of the population density. Examples of densityindependent factors are weather, floods, and fires. Logistic growth is population growth that starts with a minimum number of individuals and reaches a maximum depending on the carrying capacity of the habitat. When a population is small, the growth rate is fast because there are plenty of resources. • • • • As the population approaches the carrying capacity, resources become scarce. Competition for food, shelter, and mates increases between individuals of a population. As a result, the rate of growth slows. The population eventually stops growing when the death rate equals the birthrate. On a graph, logistic growth is characterized by an S-shaped curve. Factors That Affect Population Size • • • • • • Most populations increase or decrease. Some change with the seasons. Others have good years and bad years. Many factors cause populations to grow and shrink. Water, food, predators, and human activity are a few of many factors that affect the size of a population. Nonliving factors that affect population size are called abiotic factors. Weather and climate are the most important abiotic factors. A factor that is related to the activities of living things is called a biotic factor. Food, such as grass or other animals, is a biotic factor. Biotic factors are often density dependent because they can have a stronger influence when crowding exists. As the density of a population increases, the effects of starvation, predators, and disease often also increase. Humans affect populations of many species. Most of the time, humans cause populations to drop by disrupting habitats, introducing diseases, or introducing nonnative species. Human Population • • • • • • • • • Today, the world population is more than 6 billion people and is increasing. Better sanitation and hygiene, disease control, and agricultural technology are a few ways that science and technology have decreased the death rate of the human population. As more humans live on the planet, more resources will be needed to support them. As demand for resources increases, more pressure will be put on Earth’s ecosystems. For most of human history, there have been fewer than 10 million people. Two thousand years ago, there were only 300 million people. Around the time of the Industrial Revolution, the human population started to accelerate rapidly. Human population began accelerating exponentially starting in the late 1700s. Now, there are more than 6 billion people, and some scientists think that the population will grow to 9 billion in 50 years. Science and technology are major reasons why the human population is growing so rapidly. Advances in agricultural technology have allowed efficient production of crops and other foods. More food supports more people. Medical advances have also allowed the human population to increase. Vaccines have lowered the death rate. Other medical advances have allowed adults to live longer lives. Summary • • • • Understanding population growth is important because populations of different species interact and affect one another, including human populations. Exponential growth occurs when numbers increase by a certain factor in each successive time period. Logistic growth is population growth that starts with a minimum number of individuals and reaches a maximum depending on the carrying capacity of the habitat. Water, food, predators, and human activity are a few of many factors that affect the size of a population. Better sanitation and hygiene, disease control, and agricultural technology are a few ways that science and technology have decreased the death rate of the human population. •Preview Section 5: Interactions In Communities • • • • • Bellringer Key Ideas Predator-Prey Interactions Other Interactions Summary •Animals, Bellringer like people, live in communities. Make a list of different jobs that are done by people in your community that keep the community running. Keep in mind that some people may have more than one function in a community. • Key Ideas • How do predator-prey interactions influence both predators and prey? • What are two other types of interaction in a community? • • • • • • • Predator-Prey Interactions One of the most common interactions in communities is that between predators and their prey. Predation is the act of one organism killing another for food. Species that involve predator-prey or parasite-host relationships often develop adaptations in response to one another. Back-and-forth evolutionary adjustment between two species that interact is called coevolution. Predator-Prey Interactions, continued In parasitism, one organism feeds on another organism called a host. The host is almost always larger than the parasite and is usually harmed but not killed. • • • Parasites often live on or in their host. Therefore, the parasite depends on its host not only for food but for a place to live as well. Predator-Prey Interactions, continued Hosts try to keep parasites from infecting them. Hosts can defend themselves with their immune systems or behaviors such as scratching. • In response, parasites may evolve ways to overcome the host’s defenses. • Predator-Prey Interactions, continued • • • Herbivores are animals that eat plants. Unlike predators, herbivores do not often kill the plants. But plants do try to defend themselves. Plants defend themselves from herbivores with thorns and spines or with bad tasting chemical compounds. These chemical compounds may even cause sickness or death. • Some herbivores have evolved ways to overcome plant defenses. • Other Interactions • • • • Not all interactions between organisms result in a winner and a loser. Symbiosis is a relationship in which two species that live in close association with each other. In some forms of symbiosis, a species may benefit from the relationship. Mutualism and commensalism are two kinds of symbiotic relationships in which at least one species benefits. Other Interactions, continued • • • • • A relationship between two species in which both species benefit is called mutualism. In commensalism, two species have a relationship in which one species benefits and the other is neither harmed nor helped. Summary Species that involve predator-prey or parasite-host relationships often develop adaptations in response to one another. Mutualism and commensalism are two types of symbiotic relationships in which one or both of the species benefit. Section 6: Shaping Communities Key Ideas • How does a species’ niche affect other organisms? • How does competition for resources affect species in a community? • What factors influence the resiliency of an ecosystem? Carving a Niche • • • The unique position occupied by a species, both in terms of its physical use of its habitat and its function in an ecological community, is called a niche. A niche is not the same as a habitat. A habitat is the place where an organism lives. A niche includes the role that the organism plays in the community. This role affects the other organisms in the community. Competing for Resources • • • • • The entire range of conditions where an organism or species could survive is called its fundamental niche. Many species share parts of their fundamental niche with other species. Sometimes, species compete for limited resources. Because of this competition, a species almost never inhabits its entire fundamental niche. Competition for resources between species shapes a species’ fundamental niche. The actual niche that a species occupies in a community is called its realized niche. Sometimes, competition results in fights between rivals. Many competitive interactions do not involve direct contests. But when one individual takes a resource, the resource is no longer available for another individual. • • • • • • • • Competition has several possible outcomes. Sometimes, one species wins, and the other loses. The loser is eliminated from the habitat. Other times, competitors can survive together in the same habitat. They are able to survive together because they divide the resources. No two species that are too similar can coexist because they are too similar in their needs. One will be slightly better at getting the resources on which they both depend. The more successful species will dominate the resources. The less successful species will either die off or have to move to another ecosystem. Eventually, the better competitor will be the only one left. One species eliminating another through competition is called competitive exclusion. Sometimes, competitors eat the same kinds of food and are found in the same places. These competitors divide resources by feeding in slightly different ways or slightly different places. Ecosystem Resiliency • • Ecosystems can be destroyed or damaged by severe weather, humans, or introduced species. Other factors can help keep an ecosystem stable. Interactions between organisms and the number of species in an ecosystem add to the resiliency of an ecosystem. • Higher biodiversity often helps make an ecosystem more resilient. • Predation can reduce the effects of competition among species. • • Predators can influence more than their prey. When predators eat one species, they may reduce competition among other species. A keystone species is a species that is critical to an ecosystem because the species affects the survival and number of many other species in its community. Summary • • • A niche includes the role that the organism plays in the community. This role affects the other organisms in the community. Competition for resources between species shapes a species’ fundamental niche. Interactions between organisms and the number of species in an ecosystem add to the stability of an ecosystem. • Section 7: An Interconnected Planet Preview • • • • • • Bellringer Key Ideas Humans and the Environment Resources The Environment and Health Summary • Bellringer List examples of chemical pollution from industry, agriculture, or everyday use. What are some possible effects that these pollutants can have on the environment? • Key Ideas • How are humans and the environment connected? • What is the difference between renewable resources and nonrenewable resources? • How can the state of the environment affect a person’s health and quality of life? • Humans and the Environment • Humans now live in almost every kind of ecosystem on Earth. • As human population increases, the impact of humans on the environment increases. • Humans are a part of the environment and can affect the resilience of the environment. The more that the human population grows, the more resources from the environment we will need to survive. • Humans and the Environment, continued • Earth is an interconnected planet: we depend on the environment, and the environment is affected by our actions. • Learning about this connectedness helps us care for the environment and ensures that the environment will continue to support us and other species on Earth. • Resources • Earth’s resources are described as renewable or nonrenewable. • Renewable resources are natural resources that can be replaced at the same rate at which they are consumed. • A renewable resource’s supply is either so large or so constantly renewed that it will never be used up. • However, a resource can be renewable but still be used up if it is used faster than it can be renewed. • Resources, continued • Nonrenewable resources are resources that form at a rate that is much slower than the rate at which they are consumed. • Most of our energy today comes from fossil fuels. Fossil fuels are nonrenewable energy resources that formed from the remains of organisms that lived long ago. • Resources, continued • Fossil fuels such as coal, oil, and natural gas, are nonrenewable resources because it takes millions of years for them to form. • We use fossil fuels at a rate that is faster than the rate at which they form. So, when these resources are gone, millions of years will pass before more have formed. • The Environment and Health • Our health and quality of life are affected by the state of the environment. • Pollution and habitat destruction destroy the resources we need to live, such as the air we breathe, the water we drink, and the food we eat. • Summary • Humans are a part of the environment and can affect the resilience of the environment. • Renewable resources are natural resources that can be replaced at the same rate at which they are consumed. • Nonrenewable resources are resources that form at a rate that is much slower than the rate at which they are consumed. • Pollution and habitat destruction destroy the resources we need to live, such as the air we breathe, the water we drink, and the food we eat. •Preview Section 8: Environmental Issues • • • • • • • • Bellringer Key Ideas Air Pollution Global Warming Water Pollution Soil Damage Ecosystem Disruption Summary •Brainstorm Bellringer examples of solid, liquid, and gaseous pollutants in the environment. • • • • • • • • • • Key Ideas What are the effects of air pollution? How might burning fossil fuels lead to climate change? What are some sources of water pollution? Why is soil erosion a problem? How does ecosystem disruption affect humans? Air Pollution Air pollution causes respiratory problems for people, results in acid rain, damages the ozone layer, and may affect global temperature. Acid rain is precipitation that has an unusually high concentration of sulfuric or nitric acids, which is caused by pollution. Acid rain damages forests and lakes. • • • • • • • • Air Pollution, continued The ozone layer protects life on Earth from the sun’s damaging ultraviolet (UV) rays. The ozone layer has been damaged by chlorofluorocarbons (CFCs). CFCs are human-made chemicals that are used as coolants in refrigerators and air conditioners and as propellants in spray cans. Ozone “Hole” Over Antarctica Global Warming Global temperature may be affected by air pollutants. Global warming is the gradual increase in the average global temperature. The greenhouse effect is the warming of the surface and lower atmosphere of Earth that happens when greenhouse gases in the air absorb and reradiate heat. Examples of greenhouse gases are CO2 and water vapor. • The greenhouse effect is necessary to keep Earth’s temperatures stable. • Global Warming, continued • • • • • However, Earth’s global temperatures have been rising steadily for many decades. Most scientists think that this increase in temperatures is caused by an increase in CO2. Burning fossil fuels increases the amount of CO2 in the atmosphere. Increases in atmospheric CO2 may be responsible for an increase in global temperatures. Global Warming, continued A continued increase in global temperatures has the potential to cause a number of serious environmental problems. • • • • • • • • • • • Possible damage from global warming includes melting ice sheets, sea level rise, destruction of coastal ecosystems, and changes in weather patterns. Water Pollution Water pollution can come from fertilizers and pesticides used in agriculture, livestock farms, industrial waste, oil runoff from roads, septic tanks, and unlined landfills. Pollution enters groundwater when polluted surface water percolates down through the soil. Landfills and leaking underground septic tanks are also major sources of groundwater pollution. When pollutants run off land and into rivers, both aquatic habitats and public water sources may be contaminated. Water Pollution, continued Fertilizers from farms, lawns, and golf courses can run off into a body of water, which increases the amount of nutrients in the water leading to an excessive growth of algae. Algal blooms can deplete the dissolved oxygen in a body of water. Fish and other organisms then suffocate in the oxygen-depleted water. Water Pollution Soil Damage • Fertile soil allows agriculture to supply the world with food. • Fertile soil forms from rock that is broken down by weathering. • Nutrients that make soil fertile come from the weathered rock as well as from bacteria, fungi and the remains of plants and animals. • • • • • • • • • • • • • • The processes that form just a few centimeters of fertile soil can take thousands of years. Soil Damage, continued The greatest threat to soil is soil erosion. Erosion is a process in which the materials of Earth’s surface are worn away and transported from one place to another by wind, gravity, or water. Soil erosion destroys fertile soil that we need in order to produce food. Roots from plants and trees help hold soil together and protect it from erosion. Many farming methods can lead to soil erosion by loosening the topsoil and removing plants that hold the soil in place. The topsoil can then be washed away by wind or rain. Soil Damage, continued Sustainable agricultural practices can prevent erosion Terracing changes a steep field into a series of flat steps that stop gravity from eroding the soil. Planting a cover crop, such as soybeans, restores nutrients to the soil. Crop rotation, or planting a different crop every year, slows down the depletion of nutrients in the soil. In contour plowing, rows are plowed in curves along hills instead of in straight lines. The rows then act as a series of dams, which prevent water from eroding the soil. Ecosystem Disruption Ecosystem disruptions can result in loss of biodiversity, food supplies, potential cures for diseases, and the balance of ecosystems that supports all life on Earth. We cannot avoid disrupting ecosystems as we try to meet the needs of a growing human population. • • • • • • • • • • • • • • We can learn about how our actions affect the environment so that we can create ways to conserve it. Ecosystem Disruptions, continued Over the last 50 years, about half of the world’s tropical rain forests have been cut down or burned for timber, pastureland, or farmland. This process of clearing forests is called deforestation. The problem with deforestation is that as the rain forests and other habitats disappear, so do their inhabitants. Habitat destruction and damage cause more extinction and loss of biodiversity than any other human activities do. Ecosystem Disruptions, continued Ecosystem disruption decreases the number of Earth’s species. Biodiversity affects the stability of ecosystems and the sustainability of populations. Biodiversity is the variety of organisms in a given area. Every species plays an important role in the cycling of energy and nutrients in an ecosystem. Each species either depends on or is depended on by at least one other species. Ecosystem Disruptions, continued When a species disappears, a strand in a food web disappears. If a keystone species disappears, other species may also disappear. There are many ways in which humans benefit from a variety of life forms on Earth. Humans have used a variety of organisms on Earth for food, clothing, shelter, and medicine. Ecosystem Disruptions, continued • • • • • • • • • Humans have disrupted ecosystems by intentionally and unintentionally introducing nonnative species. Many species are on the edge of extinction. Extinction is the death of every member of a species. Summary Air pollution causes respiratory problems for people, results in acid rain, damages the ozone layer, and affects global temperature. Burning fossil fuels increases the amount of CO2 in the atmosphere. Increases in atmospheric CO2 may be responsible for an increase in global temperatures. Water pollution can come from fertilizers and pesticides used in agriculture and from livestock farms, industrial waste, oil runoff from roads, septic tanks, and unlined landfills. Summary, continued Soil erosion destroys fertile soil that we need in order to produce food. Ecosystem disruptions can result in loss of biodiversity, food supplies, potential cures for diseases, and the balance of ecosystems that supports all life on Earth. • Section 9: Environmental Solutions Preview • • • • • • • • Bellringer Key Ideas Conservation and Restoration Reducing Resource Use Technology Environmental Awareness Planning for the Future Summary • Bellringer Write 3 to 4 sentences describing a global, national, or local environmental problem you have heard about and any efforts that are being undertaken to correct the problem. • Key Ideas • How do conservation and restoration solve environmental issues? • What are three ways that people can reduce the use of environmental resources? • How can research and technology affect the environment? • Key Ideas, continued • How do education and advocacy play a part in preserving the environment? • Why is it important for societies to consider environmental impact when planning for the future? • Conservation and Restoration • Two major techniques for dealing with environmental problems are conservation and restoration. • Conservation involves protecting existing natural habitats. • Restoration involves cleaning up and restoring damaged habitats. • The best way to deal with environmental problems is to prevent them from happening. Conserving habitats prevents environmental issues that arise from ecosystem disruption. • Reduce Resource Use • We can reduce our use of resources, such as water and fossil fuels for energy. We can reuse goods rather than disposing of them. Furthermore, we can recycle waste to help protect the environment. • One of the best ways that you can help solve environmental problems is by reducing the amount of energy that you use and the amount of waste that you produce. • The reuse of goods saves both money and resources. • Reduce Resource Use, continued • The process of reusing things instead of taking more resources from the environment is called recycling. • Recycling existing products generally costs less than making new ones from raw materials does. • Technology • Research and technology can help protect our environment by providing cleaner energy sources, better ways to deal with waste, and improved methods for cleaning up pollution. • Researchers must determine the cause of an environmental problem before they can provide a solution to it. • Technology, continued • Scientists make observations and collect data. After analyzing the data, a scientist may propose a solution to the environmental problem that was studied. • Proposals should take into account the costs, risks, and benefits of implementing the solution. • Environmental Awareness • Education makes people more aware of environmental issues. • Education also shows people how they can help address such issues. • Expressing support, or advocating, for efforts to protect the environment can help get more people involved in these efforts. • Environmental Awareness, continued • Many environmental problems have been solved because of the efforts of those who advocate for a solution. • Conservation groups make efforts to educate people, protect land, and influence laws through advocacy. • Environmental Awareness, continued • Some organizations work on an international level. Others work on local environmental problems. • Some groups help farmers, ranchers, and other landowners ensure the longterm conservation of their land. • Individuals and the media also play an important role in raising awareness of environmental issues. • Environmental Awareness, continued • Educating the public about the environment helps gain public support for solving environmental issues. • Environmental education can enrich people’s experience of their world and empower them to care for it. • Ecotourism is one way to educate the public about the environment. Ecotourism is a form of tourism that supports conservation of the environment. • Often, an ecotourist is given an opportunity to help solve environmental problems as part of his or her tour. • Planning for the Future • Careful planning for the future can help us avoid damaging the environment and can help us solve the environmental issues that we face. • If we want a safe, healthy, bright future, we need to actively aim for it. • Society can plan by noting the effects of certain activities, such as development and resource use. • Planning for the Future, continued • After analyzing risks, costs, and benefits to the community, the government may choose to enforce limitations on the development. • When governments plan for the future, they can protect resources for the community for years to come. • Summary • Conservation involves protecting existing natural habitats. Restoration involves cleaning up and restoring damaged habitats. • We can reduce our use of natural resources, such as water and fossil fuels for energy. We can reuse goods rather than disposing of them. Furthermore, we can recycle waste to help protect the environment. • Research and technology can help protect our environment by providing cleaner energy sources, better ways to deal with waste, and improved methods for cleaning up pollution. • Summary, continued • Education makes people more aware of environmental issues and of ways that they can help. Expressing support, or advocating, for efforts to protect the environment can help get more people involved. • Careful planning for the future can help us avoid damaging the environment and solve environmental issues that we currently face.