Objectives

1. Populations and the Use of Natural Resources Objectives • Summarize the typical pattern of the population growth of organisms. • Describe what happens to populations when they reach carrying capacity. • Identify environmental factors that affect population growth. Vocabulary • exponential growth • carrying capacity • density-independent factor • density-dependent factor

2. Populations and the Use of Natural Resources Resources and Organisms • All organisms need particular natural resources such as air, food, water, and, in some cases, shelter to maintain life, grow, and reproduce. • Most organisms are adapted to their immediate environment; they live in a balance with the natural resources their environment provides. • Some organisms alter their environment to better meet their needs. • Humans have an unequaled capacity to modify their environments which allows us to live in every terrestrial environment on Earth.

3. Populations and the Use of Natural Resources Resources and Population Growth • As any population increases, its demand for natural resources increases as well. • Population growth is defined as an increase in the size of a population over time. • The initial increase in a population is small but as the number of reproducing adults increases, the rate of population growth increases rapidly. • Exponential growth is a pattern of growth in which a population grows faster as it increases in size, resulting in a population explosion.

4. Populations and the Use of Natural Resources Resources and Population Growth This graph shows a rapid increase over time in the population of bacteria after just a few individuals were added to a petri dish full of nutrients. Note the J-shaped curve of the graph.

5. Populations and the Use of Natural Resources Limits to Population Growth • Eventually, one or more limiting factors, such as the availability of food, water, or clean air, will cause a population to stop increasing. • Carrying capacity is the number of organisms that any given environment can support. • A population that is at the carrying capacity for its environment is in equilibrium and will remain so as long as natural resources are available.

6. Populations and the Use of Natural Resources Limits to Population Growth Under normal conditions, populations usually reach an equilibrium with the resources available in the environment. From that point on, the population size will fluctuate around the carrying capacity.

7. Populations and the Use of Natural Resources Limits to Population Growth Environmental Limits • Density-independent factors are environmental factors, such as storms, droughts, and pollution, that affect all populations that they come in contact with, regardless of population size. • Density-dependent factors are environmental factors, such as disease, parasites, and lack of food, that increasingly affect a population as the population’s size increases.

8. Populations and the Use of Natural Resources Human Population Growth • The human population on Earth is still growing and is expected to continue to grow for at least another 50 years. • Although the human population has not yet reached the carrying capacity of Earth, demand for natural resources will continue to increase. • Humans are not the most abundant species on Earth but our use of natural resources has impacted the environment on a global scale.

9. Populations and the Use of Natural Resources Human Population Growth A graph of human population growth still shows a J-shaped curve.

10. Populations and the Use of Natural Resources Section Assessment 1. Match the following terms with their definitions. ___ exponential growth ___ carrying capacity ___ density- independent factors ___ density- dependent factors A D C B A. a pattern of growth in which a population grows faster as it increases in size B.environmental conditions that increasingly affect a population as its size increases C.environmental conditions that affect all populations that they come in contact with D. the number of organisms that an environment can support

11. Populations and the Use of Natural Resources Section Assessment 2. What happens to a population when it reaches the carrying capacity of its environment? When a population reaches the carrying capacity of its environment, growth will stop and the population size will fluctuate around the carrying capacity.

12. Populations and the Use of Natural Resources Section Assessment 3. Identify whether the following statements are true or false. ______ A flash flood is an example of a density-dependent factor. ______ On a graph, a J-curve represents exponential growth. ______ Humans are the only organism that can modify its environment. ______ All organisms require natural resources in order to survive. false true false true

13. End of Section 1

14. Human Impact on Land Resources Objectives • Describe the environmental impact of mineral extraction. • Discuss the environmental problems created by agriculture and forestry, and their solutions. • Explain the environmental impact of urban development. Vocabulary • reclamation • biodiversity • monoculture • deforestation • bioremediation

15. Human Impact on Land Resources Human Impact on Land Resources • Each year, a typical person in North America consumes resources equal to the renewable yield from approximately 5 ha (about 12.35 acres) of forest and farmland. • Through our use of mineral resources, food, lumber, and living space, humans have a significant impact on Earth’s surface.

16. Human Impact on Land Resources Extraction of Mineral Resources • Modern societies require huge amounts of land resources, including iron, aluminum, copper, sand, gravel, and limestone. • Finding a balance between the need for mineral resources and controlling the environmental change caused by extraction can be difficult.

17. Human Impact on Land Resources Extraction of Mineral Resources Underground Mining • Underground mining, also called subsurface mining, is used where mineral resources lie deep under the ground. • Underground mining is less disruptive to Earth’s surface than surface mining, but it still has impacts on the environment. • Rainwater seeping through piles of mining waste can become contaminated with toxic metals as well as other chemicals causing water pollution.

18. Human Impact on Land Resources Extraction of Mineral Resources Surface Mining • Mineral and ore deposits found just beneath Earth’s surface can be extracted by removing huge amounts of overlying soil and rock. • Mining in this way completely changes the landscape. • In the United States, the Surface Mining Control and Reclamation Act of 1977 requires reclamation. • Reclamation is the process of restoring the land to its original contours and replanting vegetation.

19. Human Impact on Land Resources Agriculture • Biodiversity refers to the biological diversity of an ecosystem, which is determined by the variety of species of plants and animals. • Ecosystems that have high biodiversity are more stable than those with fewer species.

20. Human Impact on Land Resources Agriculture Monoculture • When land is cleared for food production, a biologically diverse ecosystem is often replaced with a single plant species, such as corn or wheat. • Monoculture is the planting of just one species in a field. • Growing a monoculture crop is an efficient farming method, but it is more susceptible to disease than other crops.

21. Human Impact on Land Resources Agriculture Pesticides • Pesticides, including fungicides and insecticides, have played an important role in boosting food production worldwide by eliminating organisms that destroy crops. • Some pesticides remain in the environment for long periods of time and accumulate in the food chain where they may harm beneficial organisms. • Some pesticides also kill beneficial organisms, such as insect predators and worms, along with destructive organisms. • Insect populations can quickly develop resistance to an insecticide.

22. Human Impact on Land Resources Agriculture Topsoil • It can take thousands of years for topsoil to form, and thus, once it is lost, it is hard to replace. • Erosion of topsoil occurs when forests or grasslands are cleared for the first time. • The addition of fertilizers helps replace some of the nutrients that are depleted by topsoil erosion, but they cannot provide all of the lost substances. • Methods used by farmers to selectively apply fertilizers where they will provide the greatest benefit include soil analysis, careful mapping of fields, and monitoring of plant growth.

23. Human Impact on Land Resources Forestry • Worldwide, thousands of hectares of forests are cut down annually to meet the demand for firewood, charcoal, paper, and lumber. • Deforestation is the removal of trees from a forested area without adequate replanting. • Deforestation often involves clear-cutting, the complete removal of all the trees in an area. • Clear-cutting may result in the loss of topsoil through erosion which causes excess sediment loads in nearby streams.

24. Human Impact on Land Resources Forestry • The negative environmental impacts of deforestation can be minimized through the practices of selective logging, and the retention of buffer zones of trees along streambeds.

25. Human Impact on Land Resources Urban Development • An estimated 5 billion people worldwide will be living in cities and towns by the year 2025. • The development of land for the growth of urban areas has many impacts on the environment. • Natural habitats are lost as forests are cleared and wetlands are filled to provide land. • During construction, erosion of topsoil often increases until new landscaping can be established. • Land is taken away from agricultural use.

26. Human Impact on Land Resources Urban Development • Concrete and asphalt coverage prevents groundwater supplies from being recharged and increases flooding. • Increasing urbanization produces large volumes of solid waste which is often buried in landfills. • Contamination of soil and groundwater with heavy metals and poisonous chemicals occurs as a result of industrial processes.

27. Human Impact on Land Resources Urban Development This graph shows the percentage of solid waste generated by various users of natural resources in the United States annually. Municipal wastes are those wastes contributed by homes and businesses.

28. Human Impact on Land Resources Urban Development Solutions • Most environmental problems that urban development creates can be solved. • Barriers can be placed around construction sites to catch sediment from increased erosion. • In the United States, wetlands are now recognized as valuable ecosystems and are protected from development. • Modern landfills are carefully designed to minimize leakage of toxic liquids.

29. Human Impact on Land Resources Urban Development Solutions

30. Human Impact on Land Resources Urban Development Solutions • Several methods are available for cleaning up industrial toxic-waste sites. • Contaminated soil can be removed and incinerated at temperatures high enough to destroy the toxic chemicals. • Bioremediation, which has been especially useful for contamination caused by spilled gasoline and oil, is the use of organisms to clean up toxic wastes.

31. Human Impact on Land Resources Section Assessment 1. Match the following terms with their definitions. ___ reclamation ___ biodiversity ___ monoculture ___ bioremediation D C A B A. the agricultural practice of planting just one species in a field B.the practice of using organisms to clean up toxic wastes C.the variety of species in an ecosystem D. restoring previously mined land to its original contours and replanting vegetation

32. Human Impact on Land Resources Section Assessment 2. Why is a high biodiversity important? Ecosystems that have high biodiversity are more stable than those with fewer species because they are able to recover more quickly from harmful events such as disease and drought.

33. Human Impact on Land Resources Section Assessment 3. Identify whether the following statements are true or false. ______ Each year, a typical person in North America consumes resources equal to the renewable yield from about 15 ha of forest and farmland. ______ Municipal waste is the largest segment of solid waste produced in the United States each year. ______ Modern landfills can be a source of energy. ______ Insect populations can quickly develop resistance to pesticides. false false true true

34. End of Section 2

35. Human Impact on Air Resources Objectives • Describe the types and sources of air pollution. • Differentiate between the greenhouse effect and global warming. • Sequence the reactions that occur as CFCs cause ozone depletion. • Identify the causes and effects of acid precipitation. Vocabulary • smog • ozone • global warming • acid precipitation

36. Human Impact on Air Resources Human Impact on Air Resources • Smog is a photochemical haze caused by the action of solar radiation on an atmosphere polluted with hydrocarbons and nitrogen oxides mostly from automobile exhaust systems. • Ozone (O3), the major chemical in smog, is a gas molecule made up of three oxygen atoms. • Ozone is beneficial in the upper atmosphere because it absorbs and filters out harmful ultraviolet (UV) radiation. • Ground-level ozone irritates the eyes, noses, throats, and lungs of humans, and it also has harmful effects on plants.

37. Human Impact on Air Resources Human Impact on Air Resources • Air pollution also occurs in the form of particulate matter ranging in size from microscopic bits to large grains. • Particulates can lodge in lung tissues and cause breathing difficulties and lung disease.

38. Human Impact on Air Resources Global Impacts of Air Pollution • Recently, it has become clear that human activities can affect Earth on a global scale. • The global atmospheric effects of air pollution include global warming, ozone depletion, and acid precipitation.

39. Human Impact on Air Resources Global Impacts of Air Pollution Global Warming • The greenhouse effect is a natural phenomenon in which Earth’s atmosphere traps heat in the troposphere to warm Earth. • Global warming, a phenomenon related to the greenhouse effect, is an increase in Earth’s average surface temperature. • Human activities, especially the burning of fossil fuels, are largely responsible for increased levels of carbon dioxide, which is the main greenhouse gas that causes global warming.

40. Human Impact on Air Resources Global Impacts of Air Pollution Global Warming The amount of atmospheric carbon dioxide has increased greatly since the 1850s.

41. Human Impact on Air Resources Global Impacts of Air Pollution Global Warming • Earth’s mean surface temperature has risen about 0.5°C in the last century. • Some scientists predict it may rise by 1 to 3.5°C in the next 100 years as a result of global warming. • Other scientists argue that the increase in Earth’s temperature could be part of a natural pattern of climatic change.

42. Human Impact on Air Resources Global Impacts of Air Pollution Ozone Depletion • The ozone layer serves as a protective shield as it absorbs and filters out harmful UV radiation. • Chlorofluorocarbons (CFCs), which were previously used in refrigerators, cleaning agents, and as propellants in aerosol cans, used to contribute to ozone destruction in the upper atmosphere.

43. Human Impact on Air Resources Global Impacts of Air Pollution Ozone Depletion

44. Human Impact on Air Resources Global Impacts of Air Pollution Ozone Depletion • Since the mid-1980s, atmospheric studies have detected a thinning of the ozone layer, including an “ozone hole” over Antarctica. • Ozone depletion is entirely a result of human activity. • The Montreal Protocol, which 186 countries had signed by 2003, calls for a phase-out in the production and use of most ozone-destroying chemicals by developed countries by the year 2005 and developing countries by the year 2015. • Based on current trends in data, the return to pre-1980 ozone amounts over Antarctica is expected by the middle of this century.

45. Human Impact on Air Resources Global Impacts of Air Pollution Acid Precipitation • Acid precipitation is precipitation with a pH of less than 5.0. • Acid precipitation forms when sulfur dioxide and nitrogen oxides combine with atmospheric moisture to create sulfuric acid and nitric acid. • Although volcanoes and marshes add sulfur gases to the atmosphere, 90 percent of the sulfur emissions in eastern North America are of human origin.

46. Human Impact on Air Resources Global Impacts of Air Pollution Acid Precipitation Automobiles are the greatest source of the nitrogen oxides that cause acid precipitation. Electrical utilities produce most of the sulfur dioxide.

47. Human Impact on Air Resources Global Impacts of Air Pollution Acid Precipitation • Coal-burning power plants in the midwestern United States release large amounts of sulfur dioxide because the coal they burn contains high amounts of sulfur. • When acids are carried into wet weather, they become part of the rain, snow, or fog that falls to the ground in areas far from their source. • Acid precipitation causes damage to aquatic ecosystems and affects plants and soil. • It also damages stone buildings and statues, and can corrode metal structures.

48. Human Impact on Air Resources Reducing Air Pollution • Solving air pollution problems requires cooperation between multiple governments because pollution travels across borders. • There has been an international effort to reduce global air pollution caused by carbon dioxide and CFCs. • In the United States, the 1990 Clean Air Act set specific reduction goals and enforcement policies for many types of air pollution.

49. Human Impact on Air Resources Reducing Air Pollution The Clean Air Act of 1972 was an attempt to reduce the amount of air pollution in the United States. This graph tracks the emission rates of six major air pollutants over a 30-year period.

50. Human Impact on Air Resources Reducing Air Pollution • Many coal-burning power plants have installed a device such as the wet scrubber to reduce emissions of particulate matter and sulfur dioxide.