ENVR 200 Lecture Notes - Lecture 21: Heavy Metals, Deforestation, Overgrazing
7 Feb 2018
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P. e. the plains of levant in lebanon we"re completely deforested (cid:884)6(cid:882)(cid:882) bc. It"s the process by which natural habitat is transformed such that it can no longer. The industrial revolution accelerated land transformation, due to population growth, and the expand of agricultural land at the expend of forests. Landscape alteration = habitat loss = habitat alteration support the species that inhabits it. Natural ecosystems -> frontier clearings -> subsidence agriculture and small scale farms -> intensive agriculture (in addition to urban areas and protected and recreational zones) 1. 5 billion hectares (size of s. a or 12% planet coverage (ice-free) is used for crops. About 3 billion hectares (24% ice-free land) is used for pasture. Over past 40 years: 700% increase in fertilizer use and 70% increase in irrigated cropland. We used to have about 55% forest area vs. 30% now. Tropical forests disappear at a rate of 1. 8% annually. Positive feedback between agricultural production and habitat loss & degradation.
