Data from: Forest plant community as a driver of soil biodiversity: experimental evidence from collembolan assemblages through large-scale and long-term removal of oak canopy trees Quercus petraea

Plant–soil interactions are increasingly recognized to play a major role in terrestrial ecosystems functioning. However, few studies to date have focused on slow dynamic ecosystems such as forests. As they are vertically stratified by multiple vegetation strata, canopy tree removal by thinning operations could alter forest plant community through tree canopy opening. Very little is known about cascading effects on soil biodiversity. We conducted a large-scale, multi-site assessment of collembolan assemblage response to long-term canopy tree removal in sessile oak Quercus petraea temperate forests. A total of 33 experimental plots were studied covering a large gradient of canopy tree basal area, stand age and local abiotic contexts. Collembolan abundance strongly declined with canopy tree removal in early forest successional stage and this was mediated by negative effect of understory plant community composition changes, i.e. shift from moss and forb to tree seedling, fern, shrub and grass species. Negative effect of this composition shift on collembolan species richness was largely offset by positive effect of the increase in understory plant species richness. This gives support to both the plant mass-ratio and functional diversity hypotheses. Collembolan functional groups had contrasting response patterns, which were mediated by different ecological factors. Epedaphic (r-strategist) abundance and species richness increased with canopy tree removal in relation with the increase in understory plant species richness. In contrast, euedaphic (K-strategist) abundance and species richness declined with canopy tree removal in early forest successional stage in relation with changes in understory plant community composition and species richness, as well as microclimatic conditions. Overall, our study provides experimental evidence that forest plant community can be a strong driver of collembolan assemblages. It also emphasizes the role of trees as foundation species of forest ecosystems that can shape soil biodiversity through their regulation of understory plant community and ecosystem abiotic conditions.

植物-土壤互作（Plant–soil interactions）在陆地生态系统功能中的核心作用正日益得到学界的广泛认可。然而迄今为止，针对森林这类慢动态生态系统的相关研究仍较为匮乏。由于森林具有多层植被垂直结构，通过间伐移除冠层树木可通过开启林冠改变森林植物群落组成，目前学界对其引发的土壤生物多样性级联效应仍知之甚少。本研究针对温带无梗栎（Quercus petraea）林开展了大尺度多站点调查，以评估弹尾虫（Collembola）群落在长期冠层树木移除下的响应；共设置33个实验样地，覆盖了冠层树木胸高断面积、林分年龄以及局地非生物环境的大范围梯度。研究发现，在森林早期演替阶段，弹尾虫的丰度随冠层树木移除显著下降，这一效应由林下植物群落组成变化的负面作用所介导，即林下植被从苔藓、杂类草（forb）向树木实生苗、蕨类、灌木以及禾本科草本植物转变；该组成变化对弹尾虫物种丰富度的负面效应，在很大程度上被林下植物物种丰富度提升带来的正面效应所抵消，这一结果同时支持了植物质量比假说（plant mass-ratio hypothesis）与功能多样性假说（functional diversity hypothesis）。弹尾虫的不同功能类群表现出截然相反的响应模式，且该差异由不同的生态因子所介导：表栖弹尾虫（Epedaphic，r-strategist）的丰度与物种丰富度随冠层树木移除而上升，这与林下植物物种丰富度的提升密切相关；与之相反，在森林早期演替阶段，真土栖弹尾虫（Euedaphic，K-strategist）的丰度与物种丰富度随冠层树木移除而下降，这与林下植物群落组成、物种丰富度的变化以及微气候条件的改变相关。总体而言，本研究通过实验证实，森林植物群落可作为弹尾虫群落的重要调控因子，同时强调了树木作为森林生态系统基石物种的重要作用——树木可通过调控林下植物群落与生态系统非生物环境，进而塑造土壤生物多样性。