Different facets of bacterial and fungal communities drive soil multifunctionality in grasslands spanning a 3,500 km transect

1. Soil microbial communities are essential in regulating ecosystem functions and services. However, the importance of bacterial and fungal communities as predictors of multiple soil functions (i.e., soil multifunctionality) in grassland ecosystems has not been studied systematically. 2. Here, we measured soil microbial diversity, community composition, biomass, and multiple soil functions of 41 sites in five grassland ecosystems spanning a 3,500 km northeast–southwest transect. The random forest algorithm was adopted to determine the importance of geographical location, climatic, altitude, edaphic, plant, and microbial predictors in driving a proxy of soil multifunctionality (seven soil functions in this study). Moreover, structural equation models (SEMs) were employed to examine the direct and indirect effects of those predictors on soil multifunctionality. 3. Our results demonstrated that soil multifunctionality was positively driven by soil fungal diversity but not by bacterial dive...1. 土壤微生物群落（soil microbial communities）是调控生态系统功能与服务的关键类群。然而，草原生态系统中细菌与真菌群落作为多重土壤功能（即土壤多功能性（soil multifunctionality））预测因子的重要性，尚未得到系统性研究。 2. 本研究针对横跨3500公里东北-西南样带的5类草原生态系统的41个样点开展测定工作，获取了土壤微生物多样性、群落组成、生物量以及多项土壤功能数据。本研究采用随机森林算法（random forest algorithm），厘清了地理位置、气候因子、海拔、土壤因子、植物因子与微生物预测因子在驱动土壤多功能性代用指标（本研究共包含7项土壤功能）过程中的相对重要性；同时运用结构方程模型（structural equation models，SEMs），解析了上述预测因子对土壤多功能性的直接与间接效应。 3. 本研究结果显示，土壤多功能性受到土壤真菌多样性的正向调控，而细菌多样性并未产生显著驱动作用。