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Chapter 10
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In 1800s 350,000 gray wolves roamed 48 states 1850–1900: decline due to human activity U.S. Endangered Species Act: 1973 Only a few hundred wolves were left 1974 – gray wolf was placed on endangered species list 1995–1996: relocation of 41 wolves to Yellowstone Park In 2007 Yellowstone estimated they have 171 gray wolves 2008: Gray wolf no longer protected
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Forest ecosystems provide ecological services far greater in value than the value of raw materials obtained from forests. Unsustainable cutting and burning of forests, along with diseases and insects, are the chief threats to forest ecosystems. Objective 1
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Tropical deforestation is a potentially catastrophic problem because of the vital ecological services at risk, the high rate of tropical deforestation, and its growing contribution to global warming.
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Old-growth a.k.a primary forest Uncut or regenerate forest that has not been disturbed by human activity or natural disaster for 200 years Account for 36% of world’s forests Second-growth forest Have been disturbed by human activity or natural disaster 60% of world’s forests Tree plantation, tree farm or commercial forest Managed tract with uniformly aged trees Clear cut and then replanted in a regular cycle May supply most of the industrial wood in the future 4% of world’s forests Objective 2
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An Old-Growth ForestAn Old-Growth Tropical Forest
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Rotation Cycle of Cutting and Regrowth of a Monoculture Tree Plantation
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Fig. 10-3a, p. 216
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Support energy flow and chemical cycling Reduce soil erosion Absorb and release water Purify water and air Influence local and regional climate Store atmospheric carbon Objective 3 Wood for fuel Lumber Pulp to make paper Mining Livestock grazing Recreation Employment Habitats
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Forests valued for ecological services Nutrient cycling Climate regulation Erosion control Waste treatment Recreation Raw materials Forest valued for economic services Estimated $4.7 Trillion per year Home for 2/3 rds of the terrestrial species
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Increased erosion Sediment runoff into waterways Habitat fragmentation Loss of biodiversity Invasion by Nonnative pests Disease Wildlife species Objective 4
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a.Selective Harvesting b.Clear Cutting c.Strip Cutting
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Fig. 10-6a, p. 219
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Fig. 10-6b, p. 219
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Fig. 10-6c, p. 219
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Objective 5
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Surface fires Usually burn leaf litter and undergrowth May kill seedlings and small trees Mature trees survive May provide food in the form of vegetation that sprouts after fire Crown fires Extremely hot: burns whole trees Kill wildlife Increase soil erosion Objective 6
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Introduction of foreign diseases and insects Accidental Deliberate Global warming Rising temperatures Trees more susceptible to diseases and pests Drier forests: more fires More greenhouse gases
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Deforestation Temporary or permanent removal of large expanses of forest Mostly in Tropical Forests Especially in Latin America, Indonesia, and Africa Recently there has been increase of boreal forest deforestation Especially in Alaska, Canada, Scandinavia, and Russia Objective 7
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Extreme Tropical Deforestation in Thailand
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Forest cover 30% of US land Provide habitat for 80% of wildlife species Forests of the eastern United States decimated between 1620 and 1920 Have grown back naturally through secondary ecological succession Biologically simplified tree plantations that reduce biodiversity have replaced many old growth forests
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Tropical forests cover 6% of the earth’s land area Majority of loss since 1950 Mature tropical forests once covered twice as much area Brazil & Indonesia lead the world in tropical forest loss Objective 8
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Satellite Images of Amazon Deforestation 1975 Satellite Images of Amazon Deforestation 2001
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Large Areas of Brazil’s Amazon Basin Are Burned
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We can sustain forests by emphasizing the economic value of their ecological services, protecting old-growth forests, harvesting trees no faster than they are replenished, and using sustainable substitute resources. Objective 9
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The Smokey Bear educational campaign Forest Service and National Advertising Council Prescribed fires Careful planning and monitoring Alternative to prescribed burns = goats! Allow fires on public lands to burn Removes flammable underbrush and small trees Protect structures in fire-prone areas by thinning a zone of about 200 feet and eliminate the use of flammable materials. Objective 10
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2003 Healthy Forests Restoration Act Allows timber companies to cut down economically valuable medium-size and large trees in 71% of the country’s national forests in return for clearing smaller, more fire-prone trees and underbrush. The companies are not required to conduct prescribed burns after completing the thinning process.
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Collins Pine Owns & manages productive timberland in NE CA Since 1993 the Scientific Certification Systems has evaluated Collins Pine timber production. Concluded that Collin Pine consistently has not exceeded long term forest regeneration. Forest Stewardship Council Nonprofit Developed list of environmentally sound practices Certifies timber and products
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Improve the efficiency of wood use According to the Worldwatch Institute and forestry analyst up to 60% of the wood consumed in the Us is wasted unnecessarily. Make tree-free paper Paper can be made out of fiber that does not come from trees – China = rice straw U.S. = Kenaf (kuh-NAHF) Objective 11
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Fast-Growing Plant: Kenaf
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About ½ of the wood harvested each year in developed countries and ¾ of the wood harvested in developing countries is used for fuel. Possible solutions Establish small plantations of fast-growing fuelwood trees and shrubs Burn wood more efficiently Solar or wind-generated electricity Haiti: Was once a tropical paradise but is now an ecological disaster Now only 2% of it’s land is forest With the trees gone, the soil has eroded away South Korea: model for successful reforestation Forests cover 2/3 of the land surface
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Governments and Individuals Can Act to Reduce Tropical Deforestation Reduce fuelwood demand Practice small-scale sustainable agriculture and forestry in tropical forest Debt-for-nature swaps Conservation concessions Use gentler logging methods Buy certified lumber and wood products
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We can sustain the productivity of grasslands by controlling the number and distribution of grazing livestock (to avoid overgrazing) and restoring degraded grasslands. Objective 12
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Important ecological services of grasslands Soil formation Erosion control Nutrient cycling Storage of atmospheric carbon dioxide in biomass Maintenance of diversity
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Overgrazing of rangelands Reduces grass cover Leads to erosion of soil by water and wind Soil becomes compacted Enhances invasion of plant species that cattle won’t eat
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Rotational grazing Suppress growth of invasive species Herbicides Mechanical removal Controlled burning Controlled short-term trampling Replant barren areas Apply fertilizer Reduce soil erosion Objective 13
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American southwest: population surge since 1980 Land trust groups: limit land development Reduce the harmful environmental impact of herds Rotate cattle away from riparian areas Use less fertilizers and pesticides Operate ranch more economically
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Sustaining biodiversity will require protecting much more of the earth’s remaining undisturbed land area as parks and nature reserves. Objective 14
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Worldwide: 1100 major national parks
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Parks in developing countries Greatest biodiversity 1% protected against Illegal animal poaching Illegal logging and mining
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58 Major national parks in the U.S. Biggest problem may be popularity Noise Congestion Pollution Damage or destruction to vegetation and wildlife Repairs needed to trails and buildings
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Gray wolves prey on elk and push them to a higher elevation Regrowth of aspen, cottonwoods, and willows Increased population of riparian songbirds Reduced the number of coyotes Fewer attacks on cattle Wolf pups susceptible to parvovirus carried by dogs
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Conservationists’ goal: protect 20% of the earth’s land Cooperation between government and private groups Nature Conservancy Eco-philanthropists Developers and resource extractors opposition Objective 14
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Large versus small reserves The buffer zone concept United Nations: 529 biosphere reserves in 105 countries Habitat corridors between isolated reserves Advantages Disadvantages
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1963–1983: cleared much of the forest 1986–2006: forests grew from 26% to 51% Goal: to reduce net carbon dioxide emissions to zero by 2021 Eight zoned megareserves Designed to sustain around 80% of Costa Rica’s biodiversity
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Wilderness Act of 1964 How much of the United States is protected land? Roadless Rule 2005: end of roadless areas within the national forest system Johnson
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We can help sustain biodiversity by identifying severely threatened areas and protecting those with high plant diversity and those where ecosystem services are being impaired. Sustaining biodiversity will require a global effort to rehabilitate and restore damaged ecosystems. Humans dominate most of the earth’s land, and preserving biodiversity will require sharing as much of it as possible with other species. Objective 15
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1) Map global ecosystems; identify species 2) Locate and protect most endangered species 3) Restore degraded ecosystems 4) Development must be biodiversity-friendly Are new laws needed?
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Eastern Arc Mountains of Tanzania, Africa Highest concentration of endangered species on earth Threatened due to Killing of forests by farmers and loggers Hunting Fires
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How to carry out most forms of ecological restoration and rehabilitation Identify what caused the degradation Stop the abuse Reintroduce species, if possible Protect from further degradation Objective 16
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Objective 17 You know that I know that you can do this!
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