南非克留格尔国家公园马羚的种群下降:一个备择假说

本研究报道了1979年以来南非克留格尔国家公园暂时性沼泽边界对马羚( Hippotragus equinus equinus)种群下降的影响。干旱和由此导致的生境退化以及随之产生的食草动物之间的采食竞争是解释马羚种群数量下降的可能假说。我们认为,确定马羚的生境斑块选择并测定影响暂时性沼泽边界变化与马羚种群下降的关联性因子,可解释马羚种群下降的备择假说。在北部平原区,边界呈斑块状分布的沼泽是马羚的高矿质采食源。实施狩猎管理工程期间,人工做成的大多数水道分布于沼泽边界及其附近,造成马羚与其它食草动物的采食竞争和天敌捕食压力的增高。旱季降雨的缺乏,加上沼泽边界区域采食竞争以及天敌捕食压力,是引发马羚在北部平原生境普遍退化之前其种群提前下降的因素动物学报52 (2) : 406 -409 , 2006]。

Roan Hippotragus equinus population decline in Kruger National Park, South Africa: an alternative complimentary hypothesis

We report on the potential role that ephemeral wetland boundaries played in the population decline of roan antelope Hippotragus equinus equinus on the northern plains of Kruger National Park (KNP) between 1979 and the present. Broadly described, drought, associated habitat deterioration and concomitant competition for grazing by generalist herbivores were possible hypotheses explaining the decline of the roan population. We propose that understanding the grazing patch selection of roan and identifying the factors linking ephemeral wetland boundaries and roan population decline reveals an alternative, complimentary hypothesis. The wetland boundary is patchily distributed in space within the northern plains landscape that roan utilize as a mineral rich grazing resource. Most of the artificial water holes placed on the northern plains during the Water for Game management project are situated within or closely adjacent to the wetland boundary attracting increased grazing competition with generalist grazers and predation pressure. Lack of dry season rainfall, coupled with competition for grazing at the ephemeral wetland boundary, and an increase in predation pressure could have provided a trigger for the decline of roan earlier than the general broad scale habitat deterioration of the northern plains landscape.