Beneficiary feedback effects on alpine cushion benefactors become more negative with increasing cover of graminoids and in dry conditions

In facilitative interactions, the beneficiary feedback effect (BFE) has been defined as the effect of beneficiary species (facilitated species) on their benefactor. BFEs have been shown to be dependent on environmental conditions and the composition of the beneficiary community. In alpine cushion systems, BFEs are more negative with more abundant, diverse and phylogenetically aggregated communities of beneficiary species. We tested the hypothesis that the functional composition of the beneficiary communities correlates with the direction and strength of BFE received by alpine cushion benefactors and specifically that a more negative BFE would occur with increasing density of graminoids and a more positive BFE would occur with increasing density of forbs and legumes. Additionally, we predicted that the negative BFE of graminoids would increase with increasing summer aridity. We used a data base of alpine cushion communities from 30 sites throughout the world to assess the overall relat...在生物间促进相互作用（facilitative interactions）中，受益种反馈效应（beneficiary feedback effect, BFE）被定义为受益种（被促进种，facilitated species）对其促进者物种产生的作用效应。已有研究证实，受益种反馈效应的强弱取决于环境条件与受益群落的组成结构。在高山垫状植物系统（alpine cushion systems）中，当受益种种群丰度更高、多样性更丰富且系统发育聚集度更强时，受益种反馈效应的负值特征会更为显著。我们针对下述假说开展了验证：受益群落的功能组成与高山垫状植物促进者所获取的受益种反馈效应的方向和强度存在相关性；具体而言，禾本科植物（graminoids）密度升高时，受益种反馈效应会更偏向负值，而非禾本草本植物（forbs）与豆科植物（legumes）密度升高时，受益种反馈效应则会更偏向正值。此外，我们还预测：禾本科植物介导的负向受益种反馈效应会随夏季干旱程度的加剧而增强。本研究依托全球30个研究样地的高山垫状植物群落数据库，旨在评估其整体的相关