Changing plant species composition and richness benefit soil carbon sequestration under climate warming

Anthropogenic warming and land-use change are expected to accelerate global soil organic carbon (SOC) losses and change plant species composition and richness. However, how changes in plant composition and species richness mediate SOC responses to climate warming and land-use change remains poorly understood. Using data from a 7-year warming and clipping field experiment in an alpine meadow on the Qinghai-Tibetan Plateau, we examined the direct effects of warming and clipping on SOC storage versus their indirect effects mediated by plant functional type and species richness. We found that warming significantly increased SOC storage by 8.1% and clipping decreased it by 6.4%, which was closely correlated with the corresponding response of below-ground net primary productivity (BNPP). We also found a negative correlation between SOC storage and species richness, which was ascribed to the increased BNPP via enhancing the dominance of grasses and decreasing species richness under warming. Th...人为气候变暖与土地利用变化预计将加剧全球土壤有机碳（soil organic carbon, SOC）流失，并改变植物物种组成与物种丰富度。然而，植物组成与物种丰富度的变化如何调控土壤有机碳对气候变暖和土地利用变化的响应，目前仍缺乏深入认知。本研究依托青藏高原高寒草甸为期7年的增温与刈割野外控制实验数据，探究了增温与刈割对土壤有机碳储量的直接效应，以及二者通过植物功能型（plant functional type）与物种丰富度介导的间接效应。研究结果表明，增温使土壤有机碳储量显著提升8.1%，而刈割则使其降低6.4%，这一结果与地下净初级生产力（below-ground net primary productivity, BNPP）的相应响应密切相关。本研究同时发现，土壤有机碳储量与物种丰富度呈负相关关系，该现象可归因于增温条件下，草本植物优势度提升使得地下净初级生产力升高，同时伴随物种丰富度下降。……