Habitat Characteristics of Forest Fragments Determine Specialisation of Plant-Frugivore Networks in a Mosaic Forest Landscape

Plant-frugivore networks play a key role in the regeneration of sub-tropical forest ecosystems. However, information about the impact of habitat characteristics on plant-frugivore networks in fragmented forests is scarce. We investigated the importance of fruit abundance, fruiting plant species richness and canopy cover within habitat fragments for the structure and robustness of plant-frugivore networks in a mosaic forest landscape of South Africa. In total, 53 avian species were involved in fruit removal of 31 fleshy-fruiting plant species. Species specialisation was always higher for plants than for frugivores. Both species and network-level specialisation increased with increasing fruit abundance and decreased with increasing fruiting plant species richness and canopy cover within fragments. Interaction diversity was unaffected by fruit abundance and canopy cover, but increased slightly with increasing fruiting plant species richness. These findings suggest that especially the availability of resources is an important determinant of the structure of plant-frugivore networks in a fragmented forest landscape.

植物-食果动物互作网络（plant-frugivore network）在亚热带森林生态系统的自然恢复中发挥着关键作用。然而，目前针对破碎化森林中生境特征对植物-食果动物互作网络的影响的相关研究仍较为匮乏。本研究以南非的镶嵌型森林景观为研究区域，探讨了生境片段内的果实丰度、结果植物物种丰富度与冠层覆盖度对植物-食果动物互作网络结构与鲁棒性的重要作用。研究共记录到53种鸟类参与31种肉质果植物的果实取食活动。植物的物种特化程度始终高于食果动物。物种水平与网络水平的特化程度均随果实丰度的提升而升高，且随生境片段内结果植物物种丰富度、冠层覆盖度的增加而降低。互作多样性不受果实丰度与冠层覆盖度的影响，但随结果植物物种丰富度的提升略有升高。本研究结果表明，资源可获得性尤其是决定破碎化森林景观中植物-食果动物互作网络结构的重要因素。