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17 Land Resources
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Land Use – World Wide One of the best ways to protect endangered & threated species restore natural areas World wide humans use ~3% of the total land area for cities ~38% for agriculture ~29% available / potential for human development
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Land Use - United States 55% of US land is privately owned 3% by Native American tribes 35% of US land is owned by the fed government 7% by local & state Management of public & private land Economic factors largely control land use “Wide-use movement” Believe the primary purpose of fed land is to enhance economic growth “Environmental movement” Believe fed lands are a legacy of the U.S. citizens (preserve)
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Land Use - United States
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Wilderness Parks & Wildlife Refuges Wilderness protected area of land in which no human development is permitted (no permanent living) Wilderness Act (1964) Set aside federally owned land Areas to remain natural and unchanged for the future gen. to enjoy Given the highest protection of any public land Managed by NPS, USFS, FWS, &BLM
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National Park System (NPS) Created in 1916 Currently includes 58 parks Primary goal Teach people about the natural environment, management of natural resources and history of a site Yosemite National Park
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National Park System Threats to U.S. Parks Crime & Vandalism Traffic jams Pollution of the soil, water and air Resource violations, litter (Cutting of gov. funding) Natural Regulation Policy to let nature take it course No culling wildlife (elk) or suppressing wildfire
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National Wildlife Refuges System 1903, Theodore Roosevelt Most extensive network of lands & waters committed to wildlife habitat in the world 535 refuges nationwide Represent all major ecosystems found in US Mission To preserve lands and waters for the conservation of fishes, wildlife and plants of the US
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Forests Role in Hydrologic Cycle Local & Regional ppt. Regulate global biogeochemical cycles Forest Topics Forest Management Deforestation Forest Trends in the US Trends in Tropical Forests Boreal Forests
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Forest Management Traditional Forest Management Managed for timber production Low diversity- monoculture Ecological Sustainable Forest Management Environmentally balanced Diverse trees Prevent soil erosion Preserve watersheds Wildlife corridors- unlogged / undeveloped areas Provide escape routes, migration routes & more territories of increased biodiversity
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Harvesting Trees US, Canada, Russia, Brazil, and China currently produce more than half of the worlds timber. 50% of harvested wood goes to make fuelwood charcoal Harvesting trees Selective cutting Shelterwood cutting Seed tree cutting Clearcutting NONE of these methods are currently used
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Deforestation Temporary or permanent clearance of large expanses of forest for agriculture or other use World forests shrank 32 million acres annually from 2000–2010 Causes Fire Expansion of agriculture Construction of roads Tree harvest Insect and disease Production of hydroelectric power Results of Deforestation Decreased soil fertility Uncontrolled soil erosion Increased sedimentation of waterways Formation of deserts Extinction of species Global climate changes
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Forest Trends in US US has 155 national forests Most temperature forest are steady or expanding Returning stands lack biodiversity of original forests More than 50% of US forest are privately owned Forest Legacy Program (1990) Helps private land owners protect forestlands from development Conservation easement Legal agreements that protect privately owned land forests from development for a number of years
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Concervation Tongass National Park Largest national forest in the US (17 million acres) One of world’s few temperate rainforests Prime logging area Roadless area conservation Politics rule – Lots of flip flopping over the years Fighting to conserve
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Tropical rainforests & tropical dry forests Tropical rainforests Occur in warm moist climates (> 200cm of ppt. annually) Central & south America, Africa, & Southeast Asia Tropical Dry forests Less ppt. than rain forests (prolonged dry seasons) India, Kenya, Zimbabwe, Egypt & Brazil
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Disappearing Tropical Rain Forests Remaining tropical rain forests are being cleared and burned at a rate unprecedented in human history Immediate causes Population growth Subsistence agriculture maintaining or supporting oneself at a minimum level Commercial logging Cattle ranching Other causes Mining Hydroelectric power Human Settlement in a Brazilian Tropical Rain Forest
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Disappearing Tropical Dry Forests Slash-and-burn agriculture Practiced by ~200-500 million subsistence farmers agricultural technique that involves cutting and burning of trees and plants to make farm land Primarily destroyed for fuel wood Used for heating and cooking 1 st crop yield is generally high Soil productivity declines rapidly if it is done over and over Led to fuel crisis in many countries & large scale errosion Increase in waterborne diseases cooking water is not boiled
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Boreal Forests (Taiga) World’s largest biome Alaska, Canada, Scandinavia, & Northern Russia 1 0 source of world’s industrial wood & wood fiber Harvested (Extensively) by clearcut loggingare Evergreen trees( spruce, fir, cedar, and hemlock) Biome - climatically and geographically defined as contiguous areas with similar climatic conditions
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Rangeland lands Land that is not intensively managed and is used for grazing livestock Degradation & Deforestation Animals exceed land’s carrying capacity (K) Max # of animals that the land can sustain over an indefinite period without degradation When the K exceeds Overgrazing leaves ground barren Land degradation Natural or human-induced process that decreases future ability of land to support crops or livestock Desertification Degradation of once fertile land into nonproductive desert
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Rangeland Trends in US Make up 30% of total US land area Mostly in the western states 1/3 publicly owned & 2/3 privately owned Pressure from developers to subdivide Public rangeland managed by: Taylor Grazing Act (1934) Federal Land Policy and Management Act (1976) Conditions of public rangeland are slowly improving
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Agricultural Land US has 300 million acres of prime farmland Suburban sprawl Parking lots Housing developments Shopping malls
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Wetlands Lands that are usually covered with water for at least part of the year Characteristic soils, and water-tolerant vegetation Transitional lands between aquatic & terrestrial Benefits Habitat for migratory waterfowl and wildlife Recharge groundwater Reduce damage from flooding Improve water quality Produce many commercially important products
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Human Threats to Wetlands Drained for agriculture or mosquito control Dredging for navigation Construction of dams, dykes or seawalls Filling in for solid waste disposal Road building Mining for gravel, fossil fuels, etc. Shrinking 24,300 acres per year since 1985
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Protection of Wetlands Clean Water Act (1972) 1 0 federal law in the US governing water pollution No clear definition of wetland Emergency Wetlands Resource Act (1986) allocated funds from the LWCF for the purchase of wetlands by the Sec. of Interior Instituted a National Wetlands Priority Conservation Plan Opponents of wetland protection Say that it infringes on use of privately-owned land
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Coastlines Coastal wetlands Provide food and habitat for many aquatic animals Historically regarded as wasteland Few laws protect shoreline along bays & sounds Many coastal areas overdeveloped 3.8 billion people live within 150km of coastline 6.0 billion people will likely live there by 2025 United States 14 of 20 largest US cities along coast 19 of 20 most densely populated countries along coasts
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Conservation and Land Resources Four criteria of importance of conservation: Areas lost or degraded since European colonization Number of present ecosystem of a type Estimate of the likelihood that a given ecosystem will lose significant area or be degraded in next 10 years Number of threatened & endangered species living in the ecosystem
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Conservation and Land Resources © 2012 John Wiley & Sons, Inc. All rights reserved.
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