Data from: Seed-dispersal networks respond differently to resource effects in open and forest habitats

While patterns in species diversity have been well studied across large-scale environmental gradients, little is known about how species' interaction networks change in response to abiotic and biotic factors across such gradients. Here we studied seed-dispersal networks on 50 study plots distributed over ten different habitat types on the southern slopes of Mt. Kilimanjaro, Tanzania, to disentangle the effects of climate, habitat structure, fruit diversity and fruit availability on different measures of interaction diversity. We used direct observations to record the interactions of frugivorous birds and mammals with fleshy-fruited plants and recorded climatic conditions, habitat structure, fruit diversity and availability. We found that Shannon interaction diversity (H) increased with fruit diversity and availability, whereas interaction evenness (EH) and network specialization (H2') responded differently to changes in fruit availability depending on habitat structure. The direction of the effects of fruit availability on EH and H2' differed between open habitats at the mountain base and structurally complex habitats in the forest belt. Our findings illustrate that interaction networks react differently to changes in environmental conditions in different ecosystems. Hence, our findings demonstrate that future projections of network structure and associated ecosystem functions need to account for habitat differences among ecosystems.尽管物种多样性格局在大尺度环境梯度下已得到广泛研究，但学界对物种交互网络如何响应此类梯度下的非生物与生物因子变化仍缺乏深入认知。本研究以坦桑尼亚乞力马扎罗山（Mt. Kilimanjaro）南坡10种不同生境类型下分布的50个样地为研究对象，开展种子传播网络研究，旨在厘清气候、生境结构、果实多样性及果实可获得性对物种交互网络特征的影响效应。研究采用直接观测法记录食果鸟类与哺乳类与肉质果植物的交互行为，并同步采集气候条件、生境结构、果实多样性及可获得性相关数据。结果显示，香农交互多样性指数（Shannon interaction diversity，H）随果实多样性与可获得性的提升而升高；而交互均匀度（EH）与网络特化指数（H2'）对果实可获得性变化的响应则因生境结构而异，其中山地基带开阔生境与林带结构复杂生境中，果实可获得性对EH与H2'的影响方向存在显著差异。本研究结果表明，不同生态系统中的物种交互网络对环境变化的响应模式存在分化，因此未来针对网络结构及相关生态系统功能的预测研究，需纳入生态系统间的生境差异因素。