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南非卡鲁地区的牧场在何处、为何以及在何种程度上已经荒漠化。

Where, why, and to what extent have rangelands in the Karoo, South Africa, desertified.

机构信息

FitzPatrick Institute, University of Cape Town, 7700, Rondebosch, South Africa.

出版信息

Environ Monit Assess. 1995 Jan;37(1-3):103-10. doi: 10.1007/BF00546883.

Abstract

We used simple questionnaire surveys to obtain rough categorical information on the status of semiarid and arid rangelands in the Karoo, South Africa. We sent questionnaires to extension officers of the Department of Agricultural Development, asking them to rank the condition of the rangeland in their extension districts (usually about 500 farms) on a three- or five-point scale. The questionnaire also sought information on the possible reasons for changes in the condition of the rangelands; vegetation types most at risk on mismanaged rangelands; and changes in the status of plants, birds, and mammals. Extension officers rated 35% of the semiarid rangelands in southwestern South Africa (the Karoo and southern Kalahari Desert) as being in poor condition. There was some congruency between the perceived condition of the agricultural extension district and the percentage that the stocking rate had decreased. Rangeland condition in more arid areas tends to be poor. Stocking rates have decreased disproportionately more in arid areas than in the more mesic areas of southwestern South Africa. Grasses were rated as the most threatened group of plants, and succulents the least threatened group. Overgrazing in the past was considered to be the most important cause of present-day rangeland condition, followed by present overstocking of rangelands. Antelope were considered more threatened by rangeland management than mammalian carnivores. Avian raptors and bustards, gamebirds, and tortoises were all perceived to be threatened by rangeland mismanagement.

摘要

我们采用简单的问卷调查,获取南非卡鲁半干旱和干旱牧场状况的大致分类信息。我们向农业发展部推广官员发送了问卷,要求他们根据 3 分或 5 分制对其推广区(通常约 500 个农场)的牧场状况进行评级。问卷还询问了牧场状况变化的可能原因、管理不善的牧场最危险的植被类型,以及植物、鸟类和哺乳动物状况的变化。35%的南非西南部半干旱牧场(卡鲁和卡拉哈里沙漠南部)被推广官员评为状况不佳。农业推广区的感知状况与载畜率下降的百分比之间存在一定的一致性。较干旱地区的牧场状况往往较差。载畜率在较干旱地区的下降幅度大于南非西南部较湿润地区。草类被评为受威胁最大的植物群体,肉质植物受威胁最小。过去过度放牧被认为是目前牧场状况的最重要原因,其次是目前牧场过度放牧。与食草哺乳动物相比,有蹄类动物被认为更容易受到牧场管理的威胁。猛禽和鸨、猎禽和龟类都被认为受到牧场管理不善的威胁。

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