Forest Elephants: Tree Planters of the Congo
Forest Elephants: Tree Planters of the Congo
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DOI：
10.1111/j.1744-7429.2009.00512.x
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发表时间：
2009-07-01
期刊：
影响因子：
2.1
通讯作者：
Walsh, Peter
中科院分区：
文献类型：
--
作者：
Blake, Stephen;Deem, Sharon Lynn;Walsh, Peter
大型脊椎动物的数量正在迅速减少，特别是在热带地区，那里的过度狩猎使许多森林结构完好无损，但却没有大型动物。因此，一个紧迫的问题是，如果没有大型脊椎动物，这些“空旷”的森林能否维持其生物多样性。在这里，我们研究了森林象（Loxodonta africana cyclotis）种子传播在维持刚果北部恩多基森林树木群落结构中的作用。对855个大象粪堆的分析表明，森林象比非洲森林中任何其他物种或属的大型脊椎动物传播更多完整的种子，而GPS遥测数据显示，与其他传播者相比，森林象经常将种子传播到前所未有的距离。对5667个样本的空间分布分析表明，树木的扩散机制与空间聚集规模密切相关。大象种子散布量的增加与聚集量的减少有关。在距离小于200米的情况下，仅由大象传播种子的树木的聚集性低于随机预期，这表明janen - connell效应对种子/幼苗死亡率有影响。在景观尺度上，种子传播模式预测了局地树木群落相似性在空间上的衰减速率。我们的研究结果表明，森林象（和其他大型分散动物）的消失可能导致动物分散树种的招募失败，并有利于物种贫乏的非生物分散树种的再生。
The abundance of large vertebrates is rapidly declining, particularly in the tropics where over-hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these 'empty' forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant (Loxodonta africana cyclotis) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of < 200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen-Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees.