Chapter 16 Human Impact on Ecosystems

Earth’s Resources Natural Resources Natural Resources –Part of natural environment used by humans –Include soil, water, crops, wildlife, oil, gas, minerals –Wilderness and recreation areas Renewable resources Renewable resources –Materials that can be replenished or recycled by natural processes –Oxygen, nitrogen, plants, animals, soil, water

Earth’s resources Nonrenewable resources Nonrenewable resources –Available in limited amounts and cannot be replaced or recycled by natural processes –Metals, minerals, topsoil Fossil fuels and petroleum products Fossil fuels and petroleum products –Substances made from remains of organisms buried for millions of years –Nonrenewable

Earth’s resources Extinct organisms Extinct organisms –Disappearance of a species –Last 20 years, 30 species of plants/animals have disappeared from US –Humans mainly responsible –Destruction of habitat, hunting, housing developments, destruction of forests for farmland

When demand exceeds supply Greater population, greater demand for resources Greater population, greater demand for resources –Need food, water, living space, clothing, transportation, etc. –Increases prices, may cause shortages

Ecological footprint Amount of land necessary to produce and maintain enough food and water, shelter, energy, and waste Amount of land necessary to produce and maintain enough food and water, shelter, energy, and waste Depends on the amount and efficiency of the use of resources and the toxicity level of wastes produced Depends on the amount and efficiency of the use of resources and the toxicity level of wastes produced

Ecological footprint (2006)

Land resources Topsoil needs to be replenished with humus and moisture Topsoil needs to be replenished with humus and moisture Agriculture increases the rate of soil erosion or desertification Agriculture increases the rate of soil erosion or desertification Contour plowing or leaving roots/stems from previous crops prevents erosion and enriches soils Contour plowing or leaving roots/stems from previous crops prevents erosion and enriches soils

Forest Resources Temperate forests are renewable, new seedlings are planted after logging and trees grow back Temperate forests are renewable, new seedlings are planted after logging and trees grow back Old growth forests may lose some species during deforestation due to erosion or over-grazing of the areas Old growth forests may lose some species during deforestation due to erosion or over-grazing of the areas Old growth forests should be selectively logged and replanted Old growth forests should be selectively logged and replanted

Fishery Resources Fish feed a large number of people on Earth Fish feed a large number of people on Earth Over fishing will deplete the fish populations before they can be replenished by reproduction Over fishing will deplete the fish populations before they can be replenished by reproduction Laws are being implemented to control fishing in certain areas of the oceans and during certain seasons Laws are being implemented to control fishing in certain areas of the oceans and during certain seasons

Pollution Waste products usually recycled by natural processes that exist in excess Waste products usually recycled by natural processes that exist in excess Can be in the form of microscopic particles, waste from factories/sewers, household chemicals poured down sinks Can be in the form of microscopic particles, waste from factories/sewers, household chemicals poured down sinks Cause contamination of different parts of the environment Cause contamination of different parts of the environment –Air –Water –Land

Humans burn fuel To heat homes and businesses To heat homes and businesses Power planes, cars, buses, trains Power planes, cars, buses, trains Produce electricity Produce electricity Manufacturing and industry Manufacturing and industry All release particulates All release particulates All release air pollutants All release air pollutants –CO 2, CO, nitrogen oxides, sulfur oxides, hydrocarbons: make smog

Acid rain Air pollutants react with water and oxygen in light to make sulfuric acid and nitric acid Air pollutants react with water and oxygen in light to make sulfuric acid and nitric acid Pollutants come from coal-burning factories and car exhaust Pollutants come from coal-burning factories and car exhaust Non-polluted rain has a pH of Non-polluted rain has a pH of Rain with pH lower than 5.6 is acid Rain with pH lower than 5.6 is acid

Effects of acid rain Leaches calcium, potassium, and other nutrients from soil (decreases nutrients) Leaches calcium, potassium, and other nutrients from soil (decreases nutrients) Leads to death of trees and damage to plant tissues Leads to death of trees and damage to plant tissues Interferes with nitrogen fixation (by bacteria) Interferes with nitrogen fixation (by bacteria) Severely effects lakes’ ecosystems Severely effects lakes’ ecosystems

Ozone depletion Ozone prevents harmful UV radiation from damaging living organisms Ozone prevents harmful UV radiation from damaging living organisms Ozone is thinning due to Ozone is thinning due to –Air pollutants –CFCs Legislation (2000) is in effect to decrease the release of CFCs and to recycle existing CFCs Legislation (2000) is in effect to decrease the release of CFCs and to recycle existing CFCs

Greenhouse effect Gases in atmosphere keep heat close to earth Gases in atmosphere keep heat close to earth Prevents some heat from escaping into space; Earth stays too warm Prevents some heat from escaping into space; Earth stays too warm Main gas involved is CO 2 Main gas involved is CO 2

World temperature change/CO 2 levels

Global warming Trend of increasing global temperatures Trend of increasing global temperatures In the last 100 years, the average global temperature has increased 0.74 C (major changes in temperature usually occur over tens of thousands of years) In the last 100 years, the average global temperature has increased 0.74 C (major changes in temperature usually occur over tens of thousands of years) Current evidence includes for severe types of weather (flooding, stronger tropical storms, etc.) Current evidence includes for severe types of weather (flooding, stronger tropical storms, etc.)

Water Pollution Water covers over 2/3 of Earth Water covers over 2/3 of Earth 3% is freshwater 3% is freshwater Only.1% is available for organisms Only.1% is available for organisms –Drinking, growth, carry away waste Polluted by waterborne diseases Polluted by waterborne diseases –Cholera, dysentery, hepatitis Polluted by inorganic substances Polluted by inorganic substances –Fertilizers, sediments, heated water

Water pollution Comes from runoff from farmland and cities Comes from runoff from farmland and cities Added nutrients and chemicals in runoff lands in water supplies (rivers, lakes) and stimulates plant and algae growth (decreases oxygen levels) Added nutrients and chemicals in runoff lands in water supplies (rivers, lakes) and stimulates plant and algae growth (decreases oxygen levels) Severely alters many ecosystems Severely alters many ecosystems Ecosystem health is studied through indicator species Ecosystem health is studied through indicator species –Species that come in direct contact with the water / pollutants of the ecosystem

Biomagnification Pollutants that are water soluble and picked up by organisms are excreted with wastes Pollutants that are water soluble and picked up by organisms are excreted with wastes Pollutants that are fat soluble build up in the tissues of organisms Pollutants that are fat soluble build up in the tissues of organisms With biomagnification, pollutants move up the food chain, accumulating in higher concentrations in predatory animals With biomagnification, pollutants move up the food chain, accumulating in higher concentrations in predatory animals

Biodiversity Sum of all genetic variety Sum of all genetic variety Provides food, industrial products, medicines Provides food, industrial products, medicines Human activity threatens biodiversity by Human activity threatens biodiversity by –Reducing habitats –Over hunting –Introducing toxic substances into food chains –Introducing new species into foreign areas

Land pollution Solid wastes found in landfills or burned Solid wastes found in landfills or burned Average American produces 1.8 kg of solid waste daily Average American produces 1.8 kg of solid waste daily Not broken down by decay (buried in landfills=no oxygen) Not broken down by decay (buried in landfills=no oxygen)

Habitat Habitat must be managed, not destroyed, in order to preserve biodiversity Habitat must be managed, not destroyed, in order to preserve biodiversity Organisms must have access to their range Organisms must have access to their range Habitat fragmentation is caused by a barrier that prevents organisms from accessing their entire habitat range (such as large highways) Habitat fragmentation is caused by a barrier that prevents organisms from accessing their entire habitat range (such as large highways)

Introduced species These are species brought into an area as a result of human actions These are species brought into an area as a result of human actions Also called non-native or invasive species Also called non-native or invasive species Compete with native or natural organisms for resources Compete with native or natural organisms for resources Often damaging to the ecosystem and can result in extinction of native plant/animals Often damaging to the ecosystem and can result in extinction of native plant/animals

Sustainable development Using Earth’s resources without depleting them Using Earth’s resources without depleting them Does not cause long-term environmental harm Does not cause long-term environmental harm Using natural means to take care of problems; ex: using insects to get rid of insect pests (ladybugs eat aphids) Using natural means to take care of problems; ex: using insects to get rid of insect pests (ladybugs eat aphids)

Preservation Keeping natural resources from harm and destruction Keeping natural resources from harm and destruction Yosemite Grant of 1864 was the first to protect natural areas from development Yosemite Grant of 1864 was the first to protect natural areas from development Develop parks, refuges to balance recreations and the protection of natural resources Develop parks, refuges to balance recreations and the protection of natural resources

Conservation Planned management of natural areas to prevent destruction or exploitation Planned management of natural areas to prevent destruction or exploitation EPA (1970), Clean Air Act (1970), Clean Water Act (1972), Endangered Species Act (1973) EPA (1970), Clean Air Act (1970), Clean Water Act (1972), Endangered Species Act (1973) –Bald Eagles: 791 pairs 1973; 6500 pairs 2000 Recovery programs Recovery programs –Help threatened or endangered species –Release them back to natural habitats