BIO1042 Lecture Notes - Lecture 21: Soil Retrogression And Degradation, Overgrazing, Soil Fertility
10 Oct 2018
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Document Summary
What are forests good for: provide habitat, provide clean water, provides clean air, equalizes local and regional temperatures, reduce force and impacts of winds, recreational, economic and other values. "temporary or permanent clearing of forests for agriculture or other purposes: by fire or cutting, began with early human settlements, major consequences and cataclysmic disasters. Immediate causes: spread of agriculture, domestic firewood collecting, unregulated timber harvesting. Loss of soil fertility, cultivation abandoned, overgrazing, soil erosion, no forest growth. Social economic causes: unemployment, population growth, and tenure issues, lack of government regulation of industry. Since 1980: 25% of tropical rainforest areas cleared: population of tropical countries have doubled, rapid economic growth exacerbate pressure on tropics. Deforestation and climate change: deforestation 2nd largest anthropogenic source of c02 to atmosphere, after fossil fuel combustion. Soil degradation and erosion - loss of topsoil, loss of nutrients. Increased sediment (turbidity) in rivers and coastal waters.
