Chapter 1 Summary by HC121104061330


									                Chapter Summaries - Environmental Science 121
Chapter 1 Summary
1.   All life depends on energy from the sun, solar capital, and the resources and ecological services of the earth,
     natural capital, to survive. An environmentally sustainable society provides for the current needs of its people
     without undermining the ability of future generations to do the same.

2.   The world’s population is growing exponentially, adding about 80 million people per year. Economic growth
     increases a country’s capacity to provide goods and services to its people. Economic development uses
     economic growth to improve standards of living. Globalization is a process of increasingly interconnecting
     people through social, economic, and environmental global changes.

3.   The earth’s main resources are perpetual resources like solar energy, renewable resources like forests and fresh
     water, and nonrenewable resources like oil and gas. The resources can be depleted or degraded by overuse, by
     waste, by pollution, and by man’s increasing “ecological footprint.”

4.   The principle types of pollution are air, water, soil, and food pollutants. We can prevent pollution or clean up
     pollution. Prevention is far preferable because cleaning up pollution often causes additional pollutants in
     another part of the environment.

5.   The basic causes of today’s environmental problems are population growth, wasteful use of resources, the
     tragedy of the commons, poverty, poor environment accounting, and ecological ignorance. They are
     interconnected because of political and economic practices that are not equitable for various populations, in
     resource consumption and in technological applications.

6.   The world’s current course is not sustainable. Environmental sustainable development encourages
     environmentally beneficial forms of economic growth and discourages environmentally harmful growth.

Chapter 2 Summary
1.   Science is an attempt to discover the natural world’s order and use that in describing what is likely to happen in
     nature. Scientists ask a question or identify a problem to investigate. Then, they collect scientific data through
     observation and measurement. Experiments may be used to study specific phenomena.

2.   The major components of complex systems are environmental inputs, flows within the system, and outputs to
     the environment.

3.   The basic forms of matter are elements and compounds. Matter is useful to us as a resource because it makes
     up every material substance.

4.   The major forms of energy are kinetic energy and potential energy. Energy is useful to us as a resource because
     it moves matter.

5.   The Law of Conservation of Matter states that matter is neither created nor destroyed when a physical or
     chemical change occurs.

6.   Matter can undergo three types of nuclear changes: natural radioactive decay, nuclear fission, and nuclear

7.   The First Law of Thermodynamics states that in all physical and chemical changes, energy may be converted
     from one form to another but it is neither created nor destroyed. The Second Law of Thermodynamics states
     that when energy is changed from one form to another, there is always less usable energy left.
8.   These laws, then, show that energy goes from a more useful to a less useful form and that high-quality energy
     cannot be recycled. So, the quality as well as the quantity of our resources and our environment will be

Chapter 3 Summary
1.   Ecology is the study of connections in nature.

2.   Life on earth is sustained by the one-way flow of high-quality energy from the sun, by the cycling of matter,
     and by gravity.

3.   Matter, energy, and life are the major components of an ecosystem.

4.   Energy in an ecosystem decreases in amount to each succeeding organism in a food chair or web.

5.   Soil is a complex mixture of eroded rock, mineral nutrients, water, air, decaying organic matter, and billions of
     living organisms. It covers most of the earth and provides nutrients for plant growth. Soils are formed by a
     breaking down of rock, decomposing surface litter and organic matter. Bacteria and other decomposer
     microorganisms break down some of soil’s organic compounds into simpler inorganic compounds.

6.   Matter is recycled through the earth’s ecosystem of air, land, water, and living organisms. This vast global
     recycling system is composed of nutrient cycles.

7.   Scientists study ecosystems through the use of aquarium tanks, greenhouses, and controlled indoor and outdoor
     chambers. Specific variables are carefully controlled, like temperature, light, carbon dioxide, and humidity.

8.   Two principles of sustainability found from learning how nature works are the law of conservation of matter
     and the two laws of thermodynamics.

Chapter 4 Summary
1.   Evolution is the change in a population’s genetic makeup over time. Evolution forces adaptations to changes in
     environmental conditions in a population. The diversity of life on earth reflects the wide variety of adaptations
     necessary and suggests that environmental conditions have varied widely over the life of the earth.

2.   An ecological niche is a species’ way of life or its functional role in a community. Everything that affects its
     survival and reproduction (temperature tolerance, water needs, space needs, interactions with other organisms,
     etc.) is a part of that niche. The ecological niche helps a population survive by the adaptive traits that its
     organisms have acquired.

3.   Extinction of species and formation of new species constantly change the biodiversity of the earth.

4.   In the future, evolution will continue to influence our environment. Man’s use of artificial selection and genetic
     engineering to evolve species may have unintended consequences because evolution is a long, slow process
     and is unpredictable.

Chapter 5 Summary
1.   Two major factors affect the number of species in a community: the latitude in terrestrial communities and
     salinity/nutrients in aquatic systems.

2.   Species play different roles in a community. Native species sustain the ecosystem in which they are a part.
     Some nonnative species will crowd out native species. Indicator species alert us to harmful changes in the
     community. Keystone species play ecological roles in the specific community: they may assist in pollination
     help regulate populations. Foundation species affect the community’s habitat to benefit other species.
3.   Species interact with each other in these different ways: interspecific competition, predation, parasitism,
     mutualism, and commensalism.

4.   As environmental conditions change, one species may be replaced by other groups of species. This gradual
     change in the composition of species in a given area is called ecological succession.

5.   A community has three aspects of sustaining itself: its persistence, the ability to resist being altered, its
     constant population, and its resilience in repairing damage. High biodiversity may give a community some
     edge in surviving, but we do not know this for certain.

Chapter 6 Summary
1.   Birth, death, fertility, and migration rates are the factors that determine population size. As birth rates have
     declined in developed countries, population has increased due to people’s migrating into these countries.
     Women’s fertility rates have dropped but are still above the replacement-level fertility around the world.

2.   Population size is profoundly affected by age structure. If women are past their primary child-bearing ages,
     population increase will be limited. If, however, the population has a large percentage of young women
     entering their childbearing years, the potential for large population increases is present. In general, the closer a
     country’s young women are to 15–40 years of age, the more potential for a rapidly increasing population.

3.   We can influence population size by encouraging smaller families, by encouraging adoption of children
     already born and discouraging new births. Population size is, also, affected by health care or its lack; by
     epidemics (such as AIDS); by losses through war, etc. Lack of prenatal care for expectant mothers, failure to
     protect children from communicable diseases (like measles) or wide-spread diseases (like malaria), can
     contribute to a smaller population. In the past economic development, family planning, and economic
     opportunities for women have reduced birth rates.

4.   India and China have both made efforts to control their population growth. China has been more successful
     because, as a dictatorship, it has imposed restrictions on family size with rewards and punishments for those
     who support or defy the government’s direction. India, without a policy of coercion, has reduced its birth rate;
     but the wish for male children and several children for the care of old parents has helped to maintain a growing

5.   Effective methods for slowing the growth of world population include investing in family planning, reducing
     poverty, and elevating the status of women.

Chapter 7 Summary
1.   Key factors that determine the earth’s weather are short-term atmospheric conditions such as temperature,
     pressure, moisture content, sunshine, cloud cover, precipitation, wind direction, and wind speed.

2.   Climate is a region’s long-term atmospheric conditions over decades. The two main factors in determining
     climate are average temperature and average precipitation.

3.   The average climate—annual precipitation and temperature—determines terrestrial regions with characteristic
     types of natural ecological communities. According to these two factors, biomes form.

4.   The major types of desert biomes are hot, temperate, and cold. Human activities have created large desert
     cities, destroyed soil through urban development and off-road vehicles, salinized the soil through irrigation,
     depleted underground water supplies, disturbed land and polluted, stored toxic and radioactive wastes, and
     located arrays of solar cells and solar collectors.
5.   The three major types of grasslands are tropical or savannas, temperate grasslands, and polar grassland/tundra.
     The savannas have been destroyed by grazing cattle, which destroy vegetation and kills grass through fecal
     droppings. The temperate grasslands have been used to grow crops and graze animals. As a result, the
     grasslands have disappeared. The arctic tundra has been compromised by oil drilling, mines, and military

6.   The three main types of forest biomes are tropical, temperate, and polar/boreal. Human activities have
     destroyed much of the native trees; grazing has compromised the vegetation and eliminated food sources for
     native animals. And the deforestation has changed the tropical forest’s ecosystem, leading to death of plants
     and animals. The temperate forest has a fewer number of broadleaf trees and rich forest soil; but fires, logging,
     and hunting have undermined this type of forest. The evergreen firs of the polar forest support a variety of
     wildlife. But oil drilling and oil spills have compromised the water, the wildlife, and the vegetation in the

7.   Mountain and arctic biomes play important ecological roles; they help regulate climate and effect sea levels.
     Mountain biome degradation arises from timber and mining extraction, from hydroelectric dams and
     reservoirs, from air pollution, increased tourism, and radiation from ozone depletion.

Chapter 8 Summary
1.   The basic types of aquatic life zones are the surface, middle, and bottom layers. The life in aquatic life zones is
     influenced by temperature, access to sunlight for photosynthesis, dissolved oxygen content, and availability of

2.   The major types of saltwater life zones are the coastal zone and the open sea. Coastal ecosystems contain
     estuaries, wetlands, and mangrove swamps. Because of their close proximity to man’s activities, they are under
     constant strain from water pollution, industrial run-off, construction and soil erosion, agricultural pesticides
     flowing into rivers and streams, and aquaculture farming. The open sea contains the euphotic zone, which is
     the lighted upper zone of the ocean. The bathyal zone is in the middle and is dimly lit. The lowest zone, the
     abyssal zone, is dark and very cold. But all are being affected by human activities: over-harvesting, oil spills,
     filling-in of wetland areas, agricultural and industrial development and pollution, rising sea levels, and careless
     fishing/trawling techniques.

3.   The major types of freshwater life zones are lakes, wetlands, and rivers. Human activities, such as dams or
     canals; flood control levees and dikes; and industrial, urban, agricultural pollutants all affect the flow and
     health of freshwater zones. Much of U.S. wetlands have been drained and filled to farm and/or to construct
     homes and businesses. These actions increase flood potential and encourage droughts. People overfish the
     waters; pollute the streams, rivers, and lakes; and dump excessive nutrients from pesticides and waste lots into
     the fresh water sources.

4.   We must protect aquatic life zones from the pollutants, water controls, and deterioration that we press upon
     them every day.

Chapter 9 Summary
1.   Biologists estimate extinction rates in one of three levels. Local extinction occurs when a species in a specific
     area is lost but the species is still found in other places. Ecological extinction describes a species that is so
     small it cannot play out its ecological role where it is found. Biological extinction means that the species is
     gone from the earth. Scientists use measurement and models to estimate extinction rates: studying past records,
     identifying species-area relationships, examining lists of threatened species. Extinction rates are increasing
     because of human activities. Our growing population, degrading and eliminating biological environments and
     biological hot spots all contribute to growing extinction rates.

2.   Biodiversity and species extinction are important because species provide enormous economic and ecological
     services we need to survive. In 100 years, mankind will destroy species that it would take five million years to
     rebuild. These species may provide genetic information, medicines, and information about natural processes
     we need to discover. These wild plants and animals are economic, recreational, and health resources.

3.   Many human activities endanger wildlife, such as degradation/loss of habitat; capture of wild animals, which
     prevents their breeding; overfishing, oil spills, and exposure to pesticides; and extinction from nonnative
     species, which we introduce.

4.   To prevent premature extinction of species, we must reduce threats from nonnative species; end illegal
     poaching and hunting; provide means for people to survive economically without killing native animals for
     food; maintain predator species, not destroy them; reduce greenhouse emissions and deforestation throughout
     the world; develop governmental policies to support biodiversity; and protect wild species in sanctuaries.

Chapter 10 Summary
1.   Conservation biology attempts to slow down the rate at which we are destroying and degrading the earth’s
     biodiversity through the use of rapid response strategies. Hot spots, the most endangered and species-rich
     ecosystems, receive emergency action to slow down/stop the loss of biodiversity in these systems.
     Bioinformatics manages, analyzes, and communicates basic biological and ecological information to help
     sustain biodiversity.

2.   Forests provide important ecological and economic services, are storehouses of biodiversity, and affect weather
     and climate throughout the world. Forest resource management varies according to the type of forests. In
     diverse forests, the age and size of trees are preserved to foster natural regeneration. Government policies will
     primarily determine the future of forests, including old-growth forests.

3.   Forests in the United States should be managed so as to retain as much of the forests as possible. Clear-cutting
     and seed-tree cutting methods of harvesting are scourges on the forest; selective cutting is the most reasonable
     way to harvest trees.

4.   Deforestation is one of the most serious ecological problems of this century. The earth’s forests have been
     reduced by 20–50% and the destruction continues to this day. Deforestation has many harmful environmental
     effects: reduces ecological services of forests, releases large amounts of carbon dioxide in the air, produces a
     drier and hotter climate; reduces the control of water movements, and increases soil erosion.

5.   Tropical deforestation is one of the biggest threats to world economic health and climate. To help sustain
     tropical forests, nations of the world must unite to discourage deforestation and degradation.

6.   Problems affecting parks run from little/no protection from their governments or being too small to sustain
     large animal species, to being too popular and, therefore, overused by people. Some methods for managing
     parks include: limiting the number of visitors, raising entry fees to provide funds for maintenance and
     management, managing parks in reference to nearby federal lands, discouraging development around already
     established parks, and providing more volunteers and better paid employees to maintain the parks.

7.   Only about 7% of the world’s terrestrial areas are protected from potentially harmful human activities; these
     areas need to be expanded throughout the world. In order to adequately conserve biodiversity, at least 20% of
     the earth’s land area should be protected in a global network of reserves.

8.   Wilderness is an amount of land legally set aside to prevent/minimize harm from human activities. This is land
     where human beings may visit but not remain. Wilderness areas are important for: (1) their natural beauty, (2)
     their natural biological diversity, (3) their enhancement of mental and physical health of visitors, and (4) their
     contributions to biodiversity and to evolutionary possibilities.

9.   Ecological restoration is the process of repairing damage caused by humans to the biodiversity and dynamics
     of natural ecosystems.

10. Initiatives that would help to sustain the earth’s biodiversity include:
     – Immediately preserving the world’s biological hot spots
     – Protecting the remaining old-growth forests
     – Mapping the world’s terrestrial and aquatic biodiversity
     – Identifying and taking action for the world’s marine hot spots, just as for the terrestrial hot spots
     – Protecting and restoring the world’s lakes and river systems
     – Developing a global conservation strategy that protects the earth’s terrestrial and aquatic ecosystems
     – Making conservation profitable
     – Initiating ecological restoration projects worldwide

Chapter 11 Summary
1.   Aquatic biodiversity refers to the composition of plants and animals in the fresh and salt waters of the planet.
     The economic importance of aquatic diversity lies in the conservative estimate of the value of their ecological
     services, which is $21 trillion a year. Additionally, at least 3.5 billion people depend on the seas for their
     primary source of food and this number could double to 7 billion in 2025. Many medicines have been
     developed from sea organisms: sponges, anemones, puffer fish, porcupine fish, seaweeds, etc. The waters are
     used for extensive recreational activities, not to mention commercial transportation.

2.   Human activities are undermining aquatic biodiversity by destroying and degrading coastal wetlands, coral
     reefs, seagrass beds, kelp beds, mangroves, and the ocean bottom.

3.   We can protect and sustain marine biodiversity by using laws, international treaties, and education. We must
     identify and protect species that are endangered and/or threatened. This entails cleaning up aquatic
     environments, as well as inventing fishing methods that do not destroy animals and birds inadvertently caught
     in fishing nets. Poaching and illegal harvesting of marine creatures must also be eliminated. Public aquariums
     can also educate the public about protecting marine animals and birds. Marine sanctuaries and coastal
     management can protect aquatic environments as well as their creatures.

4.   The world’s marine fisheries can be managed by setting catch limits below the maximum sustained yield
     limits, by reducing/eliminating fishing subsidies, and by charging fees for fishing in publicly owned offshore
     waters. Some areas can be protected from any kind of fishing; there should be more marine protected areas and
     more integration of coastal management practices. Develop net-escape devices for fishing boats. Restriction of
     coastal locations for fish farms, control of pollution, and decreasing the pollution of ship ballast water into the
     sea will all protect marine fisheries. Multispecies management of large marine systems offers hope for
     conserving marine resources and for renewing those resources.

5.   Wetlands can be protected, sustained, and restored by government regulations that prevent wetland loss.
     Destroyed wetlands can also be restored and adequately monitored for their protection. Development can be
     kept away from wetland areas and control of nonnative species needs to be instituted to prevent invasion into

6.   Freshwater fisheries, lakes, and rivers can be protected, sustained, and even restored by building and protecting
     populations of desirable species, by prevention of overfishing, and by decreasing populations of less desirable
     species. Laws can be enacted, and enforcers of these laws must be funded to protect scenic rivers; they should
     be protected from development and dam construction projects.

Chapter 14 Summary

1.   Tectonic plates have rearranged the earth’s continents and ocean basins over millions of years like pieces of a
     gigantic jigsaw puzzle. The plates have three types of boundaries. Natural hazards such as earthquakes and
     volcanoes are likely to be found at plate boundaries.
2.   Rocks are large, natural, continuous parts of the earth’s crust. There are three major types of rocks: igneous,
     sedimentary, and metamorphic. Rocks are affected by changes of physical and chemical conditions that change
     them over time from one type to another through the rock cycle.

3.   Mineral resources include all naturally occurring materials that are used for human purposes. These resources
     include metals and fossil fuels, and the distribution of these materials across the earth’s surface is highly
     variable leading to concentrated deposits in certain areas (e.g., diamonds in Angola or oil in Saudi Arabia).
     This unequal distribution can lead to conflicts and has implications for national security and international

4.   Mineral resource extraction methods include surface and subsurface mining. Surface mining types are open-pit,
     strip, contour strip mining, and mountain removal. Resource extraction technologies are constantly changing
     but always create some environmental disturbance. In some cases, the environmental impacts of mineral
     extraction can be severe.

5.   All mineral resources are finite but the lifetime of materials varies with the rate of use and the size of the
     resource. Recycling of mineral resources leads to a longer depletion time compared to those that cannot be
     reused or recycled.

6.   Scientists are developing new types of materials as substitutes for many metals. Mineral conservation and more
     sustainable manufacturing processes are helping to decrease our use and waste of such resources. Recent,
     dramatic increases in the cost of minerals are driving aggressive recycling of many resources and particularly
     metals (e.g., copper).

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