Spatio-temporal variation in plant-pollinator interactions

Despite the dynamic nature of communities, most research typically treated interaction networks as static entities, and only a few analysed the spatial and the temporal scale simultaneously. Here, we used spatial and temporal multilayer networks to explore the persistence of species and interactions in space and time, as well as the variation of species importance according to biotic factors. We further investigated, for the first time, the spatio-temporal variation in multilayer network structure. Species exhibited substantial turnover across time mainly due to fluctuations in phenology. In contrast, interaction turnover was more pronounced across habitats, which seems to be a common strategy of pollinators to adjust interactions spatially to different ecological scenarios. Overall, species were comparatively more important to the cohesiveness of spatial than of temporal networks. The importance of plant species fluctuated temporally due mainly to changes in flower density, whereas that of pollinators fluctuated in space and time according to the abundance. Module composition was highly unstable in time, and species were highly capable of changing partners and module affiliation across both scales. These findings emphasise the importance of avoiding not only habitat loss but also habitat fragmentation to maintain highly connected habitats in terms of species interactions.

尽管群落具有动态特性，但绝大多数相关研究均将物种互作网络视为静态实体，仅有极少数研究同时兼顾空间与时间尺度的分析。本研究采用时空多层网络（spatial and temporal multilayer networks），探究物种与互作在时空维度下的存续性，以及物种重要性随生物因子的变化规律。本研究还首次探究了多层网络结构的时空变异特征。物种在时间维度上呈现出显著的更替现象，这主要源于物候的波动。相比之下，互作更替在不同生境间更为显著，这似乎是传粉者针对不同生态场景在空间上调整其互作关系的通用策略。总体而言，物种对空间网络凝聚性的贡献相对高于其对时间网络的贡献。植物物种的重要性随时间波动主要源于花密度的变化，而传粉者的重要性则依据其种群丰度在空间与时间维度上发生波动。模块组成在时间维度上极不稳定，且物种在两种尺度下均能灵活改变其互作伙伴与模块归属。本研究结果强调，为维持物种互作层面高度连通的生境，不仅需要避免生境丧失，还需防范生境破碎化。