LAUSR

Increasing the number of global change factors (GCFs) strongly influences biodiversity and ecosystem functions. However, the specific mechanisms through which biodiversity, especially soil biodiversity, stabilise ecosystem multifunctionality under rapidly growing GCFs remain elusive. Here, we implemented a multifaceted approach involving multiple GCFs (nitrogen addition, phosphorus addition and soil acidification) in the Inner Mongolia grassland to elucidate the impact of species diversity, community composition and temporal asynchrony within plant and soil biota on multifunctional stability. Our findings showed that with an increasing number of GCFs, plant and soil biodiversity, ecosystem multifunctionality and multifunctional stability broadly decreased. The negative effects of GCFs on multifunctional stability were primarily associated with the community asynchrony of soil nematodes and plants, while the negative effects on ecosystem multifunctionality were mainly associated with the community composition of soil fungi. Additionally, the indirect influence of diversities within plants and soil biota on multifunctionality and its stability was manifested through their effects on the community composition or asynchrony. Synthesis. Our results provide new empirical evidence that soil biodiversity is at least as important as plant biodiversity in determining multifunctionality and multifunctional stability under multiple GCFs. These findings highlight the importance of conserving soil biodiversity and integrating it into conservation efforts to maintain ecosystem stability in the face of increasing GCFs.