environ. |
overgrazing Intensive grazing by animals, for example cattle, sheep or goats, on an area of pasture. It has become a serious threat to the world's rangelands and grasslands. Several factors have led to overgrazing, which leads to the soil being degraded and becoming liable to erosion by wind and rain, and even to desertification. The main pressures leading to widespread overgrazing have been the need to increase the size and numbers of herds to produce more food for an increasing human population, and the transformation of traditional pasture land into plantations to grow cash crops. Throughout the dry tropics, where traditionally herds ranged over vast areas, intensive livestock-rearing schemes have taken over, mostly to provide meat for the export market. Well-digging operations have also led to heavy concentrations of animals in small areas (在牧场地区,由于动物例如牛、绵羊或山羊密集吃草造成。它成为对世界牧场和草原的一个严重威胁。几个因素导致了过度放牧,导致土壤退化,被风雨侵蚀,甚至沙漠化。导致普遍过度放牧的主要压力是需要增加牧群的大小和数量,生产更多食物以应对增长的人口,以及传统牧场的变革,如引入种植园种植商品作物。牧群传统上分布在广大的区域,密集的家畜驯养计划,为出口市场提供肉类。) |