上海大金山岛植被功能组成对草本植物、土壤动物和细菌多样性的影响

揭示植物群落对土壤动物和微生物多样性的上行调控效应有助于理解不同营养级生物多样性的维持机制。以往的研究主要集中在植物物种多样性对土壤动物和微生物多样性的影响，而关于植被功能组成自下而上的影响研究较少。以上海大金山岛13个植物群落为对象，在分析落叶木本植物占比与树木和草本物种多样性，以及土壤动物和细菌多样性的关系基础上，利用结构方程模型区分了落叶木本植物占比对土壤动物和细菌多样性的直接与间接影响效应。结果显示：落叶木本植物占比不仅分别对草本物种多样性和土壤动物多样性分别产生直接正效应和负效应（P<0.01；P<0.05），也会通过草本物种的级联效应间接的降低地下土壤细菌多样性（P<0.10）。然而，木本植物多样性仅与草本物种多样性显著正关联（P<0.10），与土壤动物和细菌多样性无显著关联（P>0.10）。该研究结果表明，相较于木本植物多样性，落叶植物占比在中亚热带北缘森林生态系统不同营养级生物多样性维持格局中扮演着更为重要的角色。

Impacts of vegetation functional composition on herbaceous, soil fauna, and bacterial diversity in Dajinshan Island, Shanghai

Revealing the bottom-up effects of plant community on soil fauna and microbial diversity can better understanding the biodiversity maintaining mechanisms at multi-trophic levels. Previous studies have mainly focused on the effects of plant species diversity on soil fauna and microbial diversity, but the bottom-up effects of the vegetation functional composition received less attention. In this study, we firstly analyzed the relationships among deciduous woody plant proportion, tree and herbaceous species diversity, and soil fauna and bacteria diversity across 13 plant communities on Dajinshan Island, Shanghai. Then the structure equation model was used to distinguish the direct and indirect effects of deciduous woody plant proportion on soil faunal and bacterial diversity. The results showed that the proportion of deciduous wood plants had not only direct positive and negative effects on herbaceous species diversity (P<0.01) and soil fauna diversity (P<0.05), respectively; but also indirectly decreased soil bacteria diversity through the cascading effect of herbaceous species (P<0.10). However, woody plant diversity positively only linked with herbaceous species diversity, and did not correlate with soil fauna and bacteria diversity (P>0.10). These results suggest that, compared to tree species diversity, the proportion of deciduous plants plays more important role in sustaining biodiversity patterns across multi-trophic levels in forest ecosystems in the northern margin of the middle subtropical regions.