树种多样性和土壤微生物多样性对人工林生产力的影响

林分生产力通常会随着树种多样性增加而增加，但不同营养级生物多样性以及树种和土壤微生物多样性之间的相互作用如何影响生产力目前尚不清楚。以亚热带不同丰富度和树种组成的人工林为研究对象，从物种、功能性状、遗传三个维度的树种多样性以及土壤真菌和细菌系统发育多样性，探究了中国亚热带人工林树种多样性和土壤微生物多样性对林分生产力的影响。研究发现，林分生产力随树种功能多样性(FD)(P<0.001)、比叶面积群落加权均值(CWM-SLA)(P<0.01)、树种系统发育多样性(PD)(P<0.05)和土壤真菌多样性(PDF)(P<0.01)的增加而显著增加，分别解释了林分生产力总变异的12.86%、6.80%、3.67%和3.08%。FD和CWM-SLA可分别通过增加土壤真菌、细菌多样性而间接提高林分生产力。研究结果表明多营养级生物多样性是维持高水平林分生产力的基础，树种多样性和土壤微生物多样性之间的自上而下的级联效应在调节生态系统生产力方面发挥着重要作用。

Effects of tree species diversity and soil microbial diversity on stand productivity in plantations

Forest productivity generally increases with tree species diversity. However, it is unclear how biodiversity of different trophic-level and interactions between tree species diversity and soil microbial diversity affect stand productivity. In this study, we selected plantations with different tree species richness and compositions in subtropical China, to investigate the effects of tree species diversity and soil microbial diversity on stand productivity, by using indicators of tree species richness, functioanl traits diversity, phylogenetic diversity as well as phylogenetic diversity of soil fungi and bacteria. The results showed that stand productivity increased significantly with tree functional diversity (FD) (P<0.001). Community weighted mean of specific leaf area (CWM-SLA) (P<0.01), phylogenetic diversity (PD) (P<0.05) and soil fungal diversity (PDF) (P<0.01), explaining 12.86%, 6.80%, 3.67%, and 3.08% of the total variance in stand productivity, respectively. FD and CWM-SLA can indirectly improve stand productivity by increasing the diversity of soil fungi and bacteria, respectively. Our findings suggest that pluritrophic biodiversity is conducive to maintain a high level stand productivity, and the top-down cascading effect between tree species diversity and soil microbial diversity plays an important role in shaping ecosystem productivity.