Ch%202_Harper

Ch%202_Harper - Humans and Resources of The Earth: Sources...

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Humans and Resources of The Earth: Sources and Sinks Ch 2 Harper
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Sources and Sinks The Planet is a Huge System of Natural Capital Provide Economic and Ecosystem Services Sources - Resources are Physically Drawn (soil, water, forest, biodiversity) Sinks - Used to Absorb Wastes & Pollutions (e.g. solid wastes, chemicals)
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What Is a Natural Resource? Anything from nature that people use and value - Elements of atmosphere, biosphere, hydrosphere or lithosphere with which humans interact Characteristics of Natural Resources Non-renewable Form at rates slower than they are consumed Oil, gas, coal, metals Renewable Replaced continually Air, wind, water*, solar *Freshwater can be considered non-renewable given the time scale it takes to renew
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Soil Soil is a living layer of the Biosphere Porous layer of mineral and organic matter Six principal components of soil (organic & inorganic compounds) Rocks and rock particles Humus Dissolved substances Organisms Water Air
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Land Uses 98% of Human food is produced on the land Food and fiber crops are cultivated on 12% Pasture for livestock (meat and milk) 24% Forests (fuel, lumber, paper, NTFPs) 31% Deserts, Mountains, Tundra, unsuitable for agriculture 33%
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Soil Problems Top soils are rich in nutrients necessary for primary producers to carry Photosynthesis Erosion of top soil Nutrients and organic matter withdrawn faster than can be replaced Increasing intensity of agricultural use of land, plowing and overgrazing, monocropping Loss of Fertility-l ack of fallow period, use of chemical fertilizers Soil degradation may lead to desertification (no crops)
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Estimated that 1/3 of world’s soil that has ever existed has been lost Erosion is a natural process Rate of erosion and degradation in relation to rate of soil formation (human influence) 1950s – increase in productivity with the introduction of inorganic fertilizers Since 1950 the net area of cultivated land has not grown much.
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What’s happening? How does this relate to soil erosion, decreased soil fertility, and desertification? 1
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This note was uploaded on 04/11/2011 for the course EVR 3013 taught by Professor Staff during the Spring '08 term at FIU.

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Ch%202_Harper - Humans and Resources of The Earth: Sources...

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