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WHAT IS WRONG WITH THE WORLD TODAY • Working with a partner brainstorm as many environmental problems as possible. • Think about things that see or hear on the news that not only affect us but all living things. • Remember that all living things in nature are connected so overlapping problems are ok. Chapter 6: Humans in the Biosphere 6-1 A Changing Landscape A Changing Landscape • Earth as a Island – Human population is growing, but the Earth is not. – We are increasing demands on air, H20, and land. • Human Activities – We use as much energy as all other multicellular species combined. – Humans change the flow of energy and reduce ecosystem’s ability to recycle. Hunting and Gathering • • • People were nomads, traveling to take advantage of movement and cycles of animals and plants. Subsistence Hunting: taking only necessities, and making few demands on the Earth. Ways the nomads changed the environment: 1. 2. 3. Build dams Burned Grassland Caused mass extinction of large animals Agriculture • Farming gave humans a dependable source of food. – Allowed humans to stay in one place. – Lead to the formation of towns and cities. • Domestication of Animals – Pros: milk, meat, hides, wool, companionship, energy to do work – Cons: overgrazing, soil erosion, H2O supply strain The Green Revolution • Green Revolution: 1950’s, new intensive farming practices to increase crop yield. • Monoculture: large fields were cleared and planted with a single crop year after year. • Pros of Green Revolution – More food, “miracle strains”, larger equipment and machinery. • Cons of Green Revolution – Deplete H2O and energy, pest reproduction, fertilizer interferes with food webs. Industrial Growth and Urban Development • Industrial Revolution: 1800’s, addition of factories and machines to civilation • Effects of Industrial Revolution – Use of more fossil fuels – Production of waste • Suburban Sprawl: living around cities – More stress on plants and animals 6-2: Renewable and Nonrenewable Resources • Common Resource: “owned” by many people. • Tragedy of the Commons – Common resources will be eventually destroyed because no one is responsible for preserving it. Sustainable Use • Renewable Resources: can be replenished or regenerated but not unlimited. Ex: trees and water • Nonrenewable Resource: cannot be replenished Ex: fossil fuels, old-growth forest • Sustainable Use: way of using natural resources at a rate that does not deplete them Ex: using lady bugs to eat pests instead of pesticides. Land Resources • Food crops grow best in soil that is a mixture of humus, sand, clay and rock. • Plowing removes the roots of grasses that hold soil in place – Increases the rate of soil erosion • Desertification: Combination of drought, farming, overgrazing turns areas into deserts Land Resources • Ways we guard against soil erosion: – Contour plowing – Leaving stems/roots of previous year’s crop – Planting rye instead of leaving field bare – Irrigation systems – Wind breaks Invasive Species Forest Resources • Ways in which forests provide ecological services – Take out CO2, provide O2 – Products (wood, paper, lumber, fuel) – Store nutrients – Provide habitats food for organisms – Limit soil erosion Forest Resources • Old-growth Forest: never have been cut – Nonrenewable b/c takes centuries to grow back • Deforestation: loss of forest – Soil erosion – Laterite: soil that has been chemically change to a hard brick-like material Ocean Resources • Over fishing: fish are harvested faster than they can reproduce; leads to destruction of fisheries Ex: cod, salmon, herring, king crab • Aquaculture: farming of aquatic organisms Water Resources • Water is renewable, but the supply is limited • Ways to ensure the sustainable use of water: – Protect systems involved in H2O cycle Ex: wetlands purify water – Preserve forests and vegetation Air Resources • Smog: a mixture of chemical the occurs as a gray-brown haze in the atmosphere. – Caused by car exhaust, industrial emissions, and burning fossil fuels. • Particulates – microscopic particles of ash and dust • Acid Rain: water mixes with nitrogen and sulfur gases to form acid rain Invasive Species 6-3: Biodiversity • Biodiversity: sum total of genetically based variety of all organisms • Human threats to biodiversity: – – – – Altering habitats Hunting to extinction Pollution Introducing foreign species to new environments Conserving Biodiversity • Conservation: wise management of natural resources (preservation of habitats and wildlife) • Ecological Hotspot: where habitats/species are in immediate danger of extinction 6-4 Charting a Course for the Future • Two major global changes 1. Global Warming 2. Ozone layer depletion – protects from UV radiation • Overexposure to UV radiation can cause cancer. • The major cause of ozone depletion is CFC’s Ex: aerosol cans, Styrofoam, coolants in fridge