textbook questions
Discuss major factors behind species extinction and cite Earth's known mass extinction events
Although extinction occurs naturally, human impact is profoundly accelerating the rate of extinction. Island species and ecologically specialized species are especially vulnerable. When species that are vulnerable or rare encounter rapid environmental change, this heightens extinction risk. Five episodes of mass extinction are known—caused likely by asteroid impact or geologic factors. Humans may be initiating a sixth mass extinction.
Explain what is meant by an ecological footprint
An ecological footprint quantifies resource consumption by expressing the total area of biologically productive land and water required to provide the resources and waste disposal for a person or population.
Summarize and compare the major types of species interactions
Competition results when individuals or species vie for limited resources. Competition can occur within or among species and can result in coexistence or exclusion. In predation, an individual of one species kills and consumes an individual of another. In parasitism, an individual of one species derives benefit by harming (but usually not killing) an individual of another. Herbivory is an exploitative interaction in which an animal feeds on a plant. In mutualism, species benefit from one another.
Describe the field of environmental science
Environmental science is the study of how the natural world works, how our environment affects us, and how we affect our environment. Environmental science uses approaches and insights from many disciplines in the natural sciences and social sciences
Explain how family planning, the status of women, and affluence affect population growth
Family-planning programs, reproductive education, and access to modern contraceptives have reduced population growth in many nations. Fertility rates also tend to fall in societies that grant women equal rights to men, as women delay childbirth to pursue education and employment. Poorer societies tend to show faster population growth than do wealthier societies
Discuss forest management in relation to fire, pests, and climate change, and evaluate sustainable forestry certification
Foresters are now managing for recreation, wildlife habitat, and ecosystem integrity. However, increasingly severe fires are posing challenges. Fire suppression encourages eventual catastrophic fires. One solution is to reduce fuel loads by conducting prescribed burns. Today climate change and outbreaks of bark beetles are also affecting forests. Certification of sustainable forest products allows consumer choice in the marketplace to influence forestry practices.
Summarize the ecological and economic contributions of forests
Forests are ecologically complex, support a wealth of biodiversity, store carbon, and contribute ecosystem services. Forests also provide us timber and other economically important products and resources.
Discuss the reasons for seeking energy alternatives to fossil fuels
Fossil fuels are nonrenewable resources, and we are gradually depleting their easily accessible reserves. Burning fossil fuels causes air pollution that results in many environmental and health impacts and contributes to global climate change.
Assess political, social, and economic aspects of fossil fuel use
Fossil fuels impose a variety of external costs. Fossil fuel extraction creates jobs but leaves pollution. People living in areas of extraction experience a range of consequences. Today's societies are heavily reliant on fossil fuel energy, and nations that consume far more fossil fuels than they extract are especially vulnerable to supply restrictions.
Describe the science behind genetic engineering
Genetic engineering uses recombinant DNA to move genes for desirable traits from one type of organism to another. The process is both like, and unlike, traditional selective breeding.
Describe how farmers supply nutrients to crops, and assess sustainable alternatives
Growers can use inorganic or organic fertilizers to supplement nutrients for crops. Overapplying fertilizers can lead to pollution, as leaching and runoff transport nutrients that affect ecosystems and human health. Fertilizer use can be made more sustainable by targeting fertilizers directly to plants and monitoring when they are needed.
Evaluate the primary causes of biodiversity loss
Habitat loss (through destruction, alteration, or fragmentation) is the main cause of current biodiversity loss. Pollution, overharvesting, invasive species, and climate change are also important causes. Many organisms (such as amphibians) are facing impacts from a mix of factors.
Identify and discuss challenges and current efforts in conserving biodiversity
Habitat loss, the introduction of non-native species, and climate change are among the major challenges to biodiversity. People are striving to protect and restore populations, species, and habitats, even as human impacts continue to complicate efforts
Analyze the nature, growth, and potential of organic agriculture
Organic agriculture, because it reduces chemical and fossil fuel inputs, exerts fewer environmental impacts than industrial agriculture. Organic produce makes up a small part of the market but is growing rapidly. Scientific studies show that organic agriculture is productive and is a realistic alternative to industrial agriculture
Explain the challenge of feeding a growing human population
Our food production has outpaced our population growth thus far, yet nearly 800 million people still go hungry each year. Undernutrition, overnutrition, and malnutrition all challenge the goal of food security, as population and resource consumption continue to grow.
Predict the potential impacts of invasive species in communities, and suggest responses to biological invasions
People have introduced countless species to new areas. Some of these non-native species may become invasive if they do not encounter limiting factors on their population growth. Invasive species such as the zebra mussel have altered the composition, structure, and function of communities. We can respond to invasive species with prevention, control, and eradication measures
Describe the characteristics of populations that help predict population growth
Populations are characterized by size, density, distribution, sex ratio, and age structure. Rates of birth, death, immigration, and emigration determine how a population will change
explain how logistic growth, limiting factors, carrying capacity, and other fundamental concepts affect population ecology
Populations unrestrained by limiting factors undergo exponential growth. Logistic growth results from density dependence; growth slows as population size increases and approaches a carrying capacity. Reproductive strategies differ among species, and carrying capacities can change—all of which affect population ecology.
Summarize how researchers study climate
Proxy indicators—such as data from ice cores, sediment cores, tree rings, packrat middens, and coral reefs—reveal information about past climate. Direct measurements of temperature, precipitation, and other conditions tell us about current climate. Climate models serve to predict future changes in climate.
Describe the scope of human population growth
The human population currently stands at more than 7 billion and increases by 1.2% annually. It is predicted to rise to around 9.7 billion people by 2050
Discuss population growth, resource consumption, and their consequences
Today's human population size and per-person level of resource consumption both are higher than ever. Population growth magnifies our environmental impact by adding to the number of people putting demands on resources. Growing per capita consumption amplifies our environmental impact by increasing the demand each person makes on resources.
Discuss how we use water and alter freshwater systems
Water from groundwater and surface waters is used in agriculture, industry, and homes. Overextraction of water from these sources can imperil their long-term use and endanger ecosystems. Humans also modify freshwater systems by controlling floods with levees, diverting waters with canals, and creating reservoirs with dams
Describe the major classes of water pollution and propose solutions to address water pollution
Water pollution stems from point sources and non-point sources, and is caused by toxic chemicals, microbial pathogens, excessive nutrients, biodegradable wastes, sediment, and thermal pollution. Legislation and regulation have succeeded in improving water quality in developed nations in recent decades
Summarize the contributions to world energy supplies of conventional alternatives to fossil fuels
Alternatives to fossil fuels that are most widely used include nuclear power, bioenergy, and hydroelectric power. Biomass provides 10% of global primary energy use, nuclear power provides 5%, and hydropower provides 2%. Nuclear power generates 11% of the world's electricity, and hydropower generates 16%.
Discuss divergent views on population growth
Because growing populations can deplete resources, strain food supplies, and stress social systems, Thomas Malthus and Paul Ehrlich warned that overpopulation could greatly harm humanity. The contrasting Cornucopian view holds that innovation will replace consumed resources and thus that population growth can continue
Compare the benefits and costs of genetically modified foods, and assess the public debate over them
Biotech crops offer several major benefits for agriculture and society. These have not yet reached their potential but could help make our agriculture sustainable. There is no clear evidence for human health effects, but GM crops may have ecological impacts, including the spread of transgenes and an increase in herbicide pollution. Many people have ethical qualms about altering food through genetic engineering. Development of biotech foods has been controlled by multinational corporations, which many critics view as a threat to small farmers. Debate continues over whether to label GM foods in the marketplace
Suggest and assess ways we may respond to climate change
Both mitigation and adaptation are necessary. We can reduce greenhouse gas emissions with multiple strategies, including conservation, energy efficiency, clean and renewable energy sources, new automotive technologies, and investment in mass transit. International efforts to design effective treaties to restrain climate change have, so far, fallen short of what is needed. However, renewable energy technologies present economic opportunities, and some states, cities, and businesses are acting to address emissions. Carbon trading and carbon taxation offer promising ways to harness market forces and financial incentives to help reduce emissions.
Discuss how individuals and businesses can help move our economic system in a sustainable direction
Consumer choice in the marketplace, facilitated by ecolabeling, can encourage businesses to modify their operations to pursue more sustainable practices
Describe how farmers supply water to crops, and explain why sustainable alternatives are important
Conventional irrigation boosts crop yields but uses water inefficiently. Overirrigation can cause salinization and waterlogging, which lower crop yields. Farmers can conserve water by using efficient techniques and choosing crops to match soils and climates.
Explain the fundamentals of demography
Demography applies principles of population ecology to the statistical study of human populations. Demographers study size, density, distribution, age structure, and sex ratios of populations, as well as rates of birth, death, immigration, and emigration
List the levels of ecological organization
Ecologists study organisms, populations, communities, ecosystems, landscapes, and the biosphere. Habitat, niche, and specialization are vital ecological concepts
Explain how our economies exist within the environment and how economies rely on ecosystem services
Economies depend on the ecological systems around them for natural resources and ecosystem services. The depletion of resources and the degradation of ecosystem services threaten our economic well-being.
Define ecosystems and discuss how living and nonliving entities interact in ecosystem-level ecology
Ecosystems consist of all organisms and nonliving entities that occur and interact in a particular area at the same time. Matter is recycled in ecosystems, but energy flows in one direction—from producers to higher trophic levels. Input of nutrients can boost productivity—which is the generation of biomass—but an excess of nutrients can alter ecosystems and cause severe ecological and economic consequences.
Explain ecosystem services and discuss how they benefit our lives
Ecosystems provide the "goods" we know of as natural resources. Natural ecological processes provide services that we depend on for everyday living, such as cycling nutrients and purifying drinking water.
Discuss strategies for conserving energy and enhancing efficiency
Energy conservation involves both personal choices and efficient technologies. Efficiency in power plant combustion, lighting, consumer appliances, and automotive fuel efficiency all play roles in conserving energy. The rebound effect, however, can partly negate our conservation efforts. Conservation lengthens our access to fossil fuels and reduces environmental impact, but to build a sustainable society we will also need to shift to renewable energy sources.
Describe feeding relationships and energy flow, and use them to identify trophic levels and navigate food webs
Energy is transferred among trophic levels in food chains. Lower trophic levels generally contain more energy, biomass, and individuals. Food webs illustrate feeding relationships and energy flow among species in a community
Examine environmental impacts of fossil fuel use, and explore ways to minimize these impacts
In various ways, coal mining, oil and gas drilling, and oil sands extraction can alter ecosystems, pollute air and waterways, and pose health risks. Hydraulic fracturing magnifies some of these impacts. Fuels can also spill during transport, affecting soil, water, wildlife, and health. Emissions from fossil fuel combustion pollute air, pose human health risks, and drive global climate change. Public policy and advances in pollution control technology have reduced many of these emissions, but much more remains to be done. If we could safely capture carbon dioxide and sequester it underground, this would resolve a primary drawback of fossil fuels, but carbon capture and storage remains unproven so far.
Identify the energy sources that we use
Many energy sources are available, but since the industrial revolution, nonrenewable fossil fuels—including coal, natural gas, and oil—have become our primary sources of energy. We are also developing alternative sources of clean and renewable energy.
How Best to Conserve Biodiversity?
Most people view national parks and preserves as excellent ways to protect biodiversity. Yet plenty of native Hawaiian creatures face declining populations and the threat of extinction despite living within a preserve—and climate change and disease pay no heed to park boundaries.
Discuss today's extinction crisis in geologic context
Most populations of wild species are declining, and today's extinction rate is far higher than the natural background rate. Earth has experienced five mass extinction events in the past 440 million years, and human impact is now initiating a sixth mass extinction
Explain natural selection and cite evidence for this process
Natural selection is the process whereby inherited traits that enhance survival and reproduction are passed on more frequently to offspring than traits that do not enhance survival and reproduction. Evidence of natural selection can be found in countless adaptations in the diversity of wild species that exist today. It can also be found in our crop plants, pets, and farm animals, all of which have been bred by artificial selection
Discuss types of parks and protected areas and evaluate issues involved in their design
Public demand for preservation and recreation led to the creation of national parks, reserves, and wilderness areas. States, municipalities, and private land trusts all manage protected areas at the state, regional, and local levels. At the international level, biosphere reserves are one of several types of protected lands. Because habitat fragmentation affects wildlife, conservation biologists are using island biogeography theory to learn how best to design systems of parks and reserves. However, climate change is now posing new threats to protected areas.
Compare renewable and nonrenewable resources, and explain the importance of natural resources and ecosystem services to our lives
Renewable resources are unlimited or naturally replenished quickly. Nonrenewable resources are limited or replenished by the environment very slowly. Ecosystem services are benefits we receive from the normal functioning of natural systems. Natural resources and ecosystem services are essential to human life and civilization.
Assess dynamics of timber management
Resource managers have long managed for maximum sustainable yield and have begun to implement ecosystem-based management and adaptive management. The U.S. national forests were established to conserve timber and allow its sustainable extraction, although most U.S. timber today comes from private lands. Plantation forestry, featuring single-species, even-aged stands, is widespread and growing. Harvesting methods include clear-cutting and other even-aged techniques, as well as selection strategies that maintain uneven-aged stands that more closely resemble natural forest
Identify and illustrate major pressures on the global environment
Rising population and intensifying consumption magnify human impacts on the environment, which include resource depletion, air and water pollution, climate change, habitat destruction, and biodiversity loss.
Describe the scientific method and the process of science
Science is a process of using observations to test ideas. The scientific method consists of making observations, formulating questions, stating a hypothesis, generating predictions, testing predictions, and analyzing results. Scientific research occurs within a larger process of science that includes peer review, journal publication, and interaction with colleagues.
Describe Earth's climate system and explain the factors that influence global climate
Solar radiation, Milankovitch cycles, ocean absorption, and ocean circulation all influence climate. Greenhouse gases warm the atmosphere by absorbing and re-emitting infrared radiation. Earth's climate changes naturally over time, but today human influence is changing it rapidly. Our planet is now experiencing radiative forcing of 2.3 watts/m2 of thermal energy above what it was experiencing 250 years ago
Assess problems of water supply and propose solutions to address depletion of fresh water
Solutions to shortages of fresh water include increasing supplies of fresh water, through processes such as desalination, or reducing demand for water by farms, businesses, and homes. Making water reflect its true costs, by eliminating government subsidies and/or privatizing water utilities, has also been offered as a water-conserving approach.
Analyze the causes and impacts of soil erosion and land degradation, and discuss solutions
Some agricultural practices cause erosion, which results in increasingly poorer crop yields. As industrial agriculture intensifies, soils become degraded, and we have been losing millions of acres of productive cropland each year. Soil degradation is the major component of land degradation globally, and desertification affects large areas in the world's arid regions. Farming techniques such as crop rotation, contour farming, intercropping, terracing, shelterbelts, and conservation tillage help to reduce soil erosion and boost crop yields. Overgrazing can degrade soil and affect native ecosystems, but herd rotation, grazing limits, and cooperation with scientists researching grazing techniques and impacts can all contribute to more sustainable grazing.
Describe how evolution generates and shapes biodiversity
Species can form in various ways; most commonly, geographic isolation over many generations leads to speciation, producing new types of organisms that enhance Earth's biological diversity. Natural selection can be a diversifying force as populations of organisms adapt to their environments. Phylogenetic trees and the fossil record teach us about the history of life by chronicling how populations of organisms have evolved.
Discuss the concept of sustainability, and cite sustainable solutions being pursued on campuses and in the wider world
Sustainability is a term that describes living within our planet's means, such that Earth's resources can sustain us—and all life—for the future. Today we are actively developing sustainable solutions (such as replacing fossil fuels with renewable energy) that promote our quality of life while protecting and restoring our environment. Many college students are taking action to promote sustainable solutions on their campuses, including recycling, energy efficiency, water conservation, transportation alternatives, and
Explain the concept of sustainable development and discuss how environmental protection can enhance economic well-being
Sustainable development entails environmental protection, economic development, and social justice. Proponents of sustainable development believe that economic opportunity and environmental quality go hand-in-hand. Environmental protection and green technologies and industries can create rich sources of new jobs, while safeguarding environmental quality enhances a community's desirability and economic well-being.
Define sustainable development and the "triple bottom line," and discuss how sustainable development is pursued worldwide
Sustainable development promotes people's economic advancement while using resources to satisfy today's needs without compromising future needs. The United Nations has played a key role in promoting sustainable development globally. Advocates of sustainable development pursue a "triple bottom line" of environmental, economic, and social goals in a coordinated way
Identify the major sources of renewable energy and assess their recent growth and future potential
The "new renewable" energy sources include solar, wind, geothermal, and ocean energy sources. These energy sources are not truly "new," but rather are in a stage of rapid development. They currently provide far less energy and electricity than we obtain from fossil fuels or other conventional sources, but they are growing quickly. Relative to fossil fuels, the new renewables alleviate air pollution, reduce greenhouse gas emissions, and help diversify a society's energy mix. Government subsidies have long favored nonrenewable energy, but investment and public policies such as feed-in tariffs can accelerate our transition to renewable sources.
Identify the goals, methods, and consequences of the Green Revolution
The Green Revolution aimed to enhance agricultural productivity in developing nations. Scientists used selective breeding to develop crop strains that grew quickly, were more nutritious, or were resistant to disease or drought. The increased efficiency and higher yields fed more people while reducing the amount of natural land converted for farming. However, the resulting expanded use of fossil fuels, chemical fertilizers, and synthetic pesticides has increased pollution and soil degradation.
Explain how human population, affluence, and technology affect the environment
The IPAT model summarizes how environmental impact (I) results from interactions among population size (P), affluence (A), and technology (T): I = P × A × T. Rising population and rising affluence may each increase consumption and environmental impact. Technology has frequently worsened environmental degradation, but it can also help lessen our impacts
Describe solar energy and how we harness it, and evaluate its advantages and disadvantages
We can harness energy from the sun's radiation using passive methods or by active methods involving powered technology. Solar technologies include flat plate collectors for heating water and air, mirrors to concentrate solar rays, and photovoltaic (PV) cells to generate electricity. PV solar is today's fastest-growing energy source. Solar energy is perpetually renewable, creates no emissions, and enables decentralized power. However, solar radiation varies from place to place and time to time, and harnessing solar energy remains expensive.
Contrast conventional industrial, organic, and biotech approaches to agriculture, and summarize pathways toward sustainable agriculture
We can work toward sustainable agriculture in a variety of ways. Conventional industrial agriculture produces high yields, but at the cost of pollution. Organic agriculture protects resources but generally has somewhat lower yields. Biotechnology and genetic engineering aim to offer novel ways to enhance production while minimizing environmental impact. Locally supported agriculture (e.g., farmers' markets and CSAs) minimizes food miles and fossil fuel use. Mimicking natural ecosystems is a key approach to making agriculture sustainable.
Describe nuclear energy and explain how we harness it for electrical power
We gain nuclear power by converting the energy of subatomic bonds into thermal energy, using uranium isotopes. Uranium is mined, enriched, processed into pellets and fuel rods, and used in nuclear reactors. By controlling the reaction rate of nuclear fission, nuclear power plant engineers produce heat that powers electricity generation
Specify the benefits that biodiversity brings us
Wild species are sources of food, medicine, and economic development; and biodiversity supports functioning ecosystems and the services they provide us. In addition, many people feel we have a psychological need to connect with the natural world, as well as an ethical duty to preserve nature.
