Biodiversity of soil biota and plants stabilizes ecosystem multifunctionality with increasing number of global change factors

Increasing the number of global change factors (GCFs) strongly influences biodiversity and ecosystem functions. However, the specific mechanisms through which biodiversity, especially soil biodiversity, stabilizes 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 diversity 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.

全球变化因子（global change factors, GCFs）数量的增加会显著影响生物多样性与生态系统功能。然而，在全球变化因子数量快速增加的背景下，生物多样性（尤其是土壤生物多样性）维持生态系统多功能性的具体机制仍不明确。本研究在内蒙古草原开展了包含多种全球变化因子（氮添加、磷添加与土壤酸化）的多维度实验，以阐明植物与土壤生物群落的物种多样性、群落组成及时间异步性对多功能稳定性的影响。研究结果显示，随着全球变化因子数量的增加，植物与土壤生物多样性、生态系统多功能性及多功能稳定性整体呈下降趋势。全球变化因子对多功能稳定性的负面影响主要与土壤线虫和植物的群落时间异步性相关，而其对生态系统多功能性的负面影响则主要与土壤真菌的群落组成相关。此外，植物与土壤生物群落的多样性对多功能性及其稳定性的间接影响，是通过其对群落组成或时间异步性的调控作用实现的。

综合分析。本研究结果提供了新的实验证据，表明在多种全球变化因子作用下，土壤生物多样性在决定生态系统多功能性与多功能稳定性方面的重要性至少不亚于植物生物多样性。这些研究结果凸显了保护土壤生物多样性的重要性，并提示应将土壤生物多样性纳入保护工作中，以应对全球变化因子增加的趋势，维持生态系统稳定性。