Carbon stocks in central African forests enhanced by elephant disturbance
Carbon stocks in central African forests enhanced by elephant disturbance
复制标题
DOI：
10.1038/s41561-019-0395-6
复制
发表时间：
2019-09-01
影响因子：
18.3
通讯作者：
Doughty, Christopher E.
中科院分区：
文献类型：
--
作者：
Berzaghi, Fabio;Longo, Marcos;Doughty, Christopher E.
大型食草动物，如大象，可以对生态系统和生物地球化学循环产生重要影响。然而，大象对非洲热带雨林的结构、生产力和碳储量的影响在很大程度上仍然是未知的。在这里，我们通过将大象干扰纳入生态系统人口模型来量化这些影响，并通过将它们与非洲两个低地原始森林的森林调查数据进行比较来验证所建模型的影响。我们发现，由于大象的存在，森林树干密度降低，导致树木之间对光、水和空间的竞争发生变化。这些变化有利于木材密度更高、更少、更大的树木的出现。非洲雨林结构和物种构成的这种转变增加了地上生物量的长期平衡。考虑到生产力和木材密度之间的权衡，这种转变还降低了森林净初级生产力。在每公里0.5到1只动物的典型密度(2)下，大象干扰使地上生物量增加26-60吨公顷(-1)。相反，森林大象的灭绝将导致中非热带雨林地上生物量减少7%。这些模拟结果得到了实地盘点数据的证实。我们推测，森林大象的存在可能塑造了非洲热带雨林的结构，这可能在将它们与亚马逊雨林区分开来方面发挥了重要作用。
Large herbivores, such as elephants, can have important effects on ecosystems and biogeochemical cycles. Yet, the influence of elephants on the structure, productivity and carbon stocks in Africa's rainforests remain largely unknown. Here, we quantify those effects by incorporating elephant disturbance in the Ecosystem Demography model, and verify the modelled effects by comparing them with forest inventory data from two lowland primary forests in Africa. We find that the reduction of forest stem density due to the presence of elephants leads to changes in the competition for light, water and space among trees. These changes favour the emergence of fewer and larger trees with higher wood density. Such a shift in African's rainforest structure and species composition increases the long-term equilibrium of aboveground biomass. The shift also reduces the forest net primary productivity, given the trade-off between productivity and wood density. At a typical density of 0.5 to 1 animals per km(2), elephant disturbances increase aboveground biomass by 26-60 t ha(-1). Conversely, the extinction of forest elephants would result in a 7% decrease in the aboveground biomass in central African rainforests. These modelled results are confirmed by field inventory data. We speculate that the presence of forest elephants may have shaped the structure of Africa's rainforests, which probably plays an important role in differentiating them from Amazonian rainforests.