Department of Biological Sciences, University of Cape Town, P Bag Rondebosch, Cape Town, 7701, South Africa.
Organization for Tropical Studies, P. Bag, Skukuza, 1350, South Africa.
Sci Rep. 2020 Jul 16;10(1):11719. doi: 10.1038/s41598-020-68679-8.
Chronic herbivory by elephants rarely eliminates any species of woody savanna plants because these plants are typically vigorous basal resprouters after damage by fire or herbivory. In some instances, resprouting after elephant herbivory even increases stem numbers per unit area compared to protected areas. It is thus difficult to know whether an area has been severely degraded by elephant herbivory or not because although trees may be severely reduced in size, they will still be present and may even be relatively dense. By using an elephant exclosure in the Kruger National Park, South Africa, we demonstrate that this resprouting ability masks the fact that entire populations of a widespread African palm, Hyphaene petersiana, are prevented from reaching sexual maturity by chronic elephant herbivory. Besides sterilizing these palms and thus preventing their evolution and seed dispersal, the absence of the palm fruits, flowers and tall stems has other negative biodiversity impacts on their associated fauna. We suggest that to determine sustainable elephant impacts on savanna plants, conservation managers also use the reproductive condition of savanna plants rather than their presence, height or stem density.
大象的慢性食草行为很少会消灭任何一种热带草原木本植物物种，因为这些植物在受到火灾或食草动物损害后，通常会强劲地从基部长出新枝。在某些情况下，与受保护区域相比，大象食草后的再生甚至会增加单位面积的茎数。因此，很难知道一个地区是否因大象食草而严重退化，因为尽管树木的大小可能严重缩小，但它们仍然存在，甚至可能相对密集。通过在南非克鲁格国家公园使用大象围栏，我们证明这种再生能力掩盖了一个事实，即由于大象的慢性食草行为，广泛分布的非洲海枣（Hyphaene petersiana）的整个种群都无法达到性成熟。除了使这些棕榈树绝育，从而阻止它们的进化和种子传播外，棕榈果实、花朵和高大茎干的缺失对与其相关的动物群也有其他负面的生物多样性影响。我们建议，为了确定大象对热带草原植物的可持续影响，保护管理者还应使用热带草原植物的繁殖状况，而不是它们的存在、高度或茎密度。
