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Unformatted text preview: mitive wheat on cleared land Recent Before history: Effect of forest clearance by Neolithic humans indicated by the relative abundances of pollen from lake sediments Ancient
11 12 2 27/03/2013 Acceleration in modern times: Deforestation in North America Logging California redwood 1620 1920
13 Recovery in some places (Rhode Island)… …continued harvest in others (coniferous forest cut for paper pulp in Maine, maritimes). Some tropical clearing is subsistence “slash and burn” for garden plots Current deforestation mostly in the tropics 17 3 27/03/2013 Other is for lumber, pulp, or plantation clearing Logging in Sarawak, Borneo Oil palm plantation: oil for food, biodiesel Tropical forests contain great stores of carbon Asian fires of 1997‐1998: estimates of 5 million hectares • Near maximum: Indonesian Kalimantan swamp forest on peat soils
– Living plants: ~600 tonnes/hectare
– Dead plant material in soil (peat): ~340 tonnes/ha • Usually too wet to burn, but logging causes drying
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- Spring '13