Community assembly mediate multitrophic biodiversity and soil multifunctionality relationships under climate warming and altered precipitation

Community assembly processes govern species diversity and composition, which may indirectly influence ecosystem multifunctionality. Compared to single-trophic diversity, multitrophic diversity is considered to play a greater role in influencing ecosystem multifunctionality. However, the knowledge of how multitrophic community assembly affects soil multifunctionality through species diversity regulation remains limited, particularly under climate change.Using a long-term field experiment established in 2017 with warming and alter precipitation, we surveyed species diversity and composition across bacteria, fungi, nematodes, and plants. We analyzed multitrophic community assembly processes and quantified soil multifunctionality and its spatial turnover. Our objectives were to elucidate mechanisms through which warming and alter precipitation affect multitrophic diversity and subsequently affect soil multifunctionality.Warming significantly reduced α-diversity but increased β-diversity of multitrophic community. These changes were primarily mediated by climate-induced changes in the stochasticity ratio. Furthermore, warming indirectly reduced the network complexity of multitrophic community by reducing the α-diversity of multitrophic community, and further decreased soil multifunctionality. The interaction between warming and precipitation changes had a significant effect on β multifunctionality. Both bacterial and fungal β-diversity significantly enhanced soil β-multifunctionality.These findings improved our understanding of the causes (community assembly processes) and consequences (for ecosystem functioning) of biodiversity change. This study suggested that multitrophic community better sustain soil multifunctionality than single-trophic community, and highlight the critical role of microbial community in driving spatial turnover of soil multifunctionality.