Richness-stability relationships (RSRs), such as richness-resistance relationship and richness-resilience relationship, are a basic, but controversial, question in ecology. RSRs vary among different communities, with the positive and negative interactions among community members considered as the potential cause of different RSRs. However, there is still no empirical data to support the relationship between these interactions and RSRs. To confirm the potential effect of community interactions on RSRs, we selected soil microbial communities from ecosystems that represented 5 different successional stages and conducted a simulated stress-recovery incubation. Our results showed that soil microbial community RSRs were controlled by the balance of positive and negative interactions. If positive and negative interaction of the microbial community network were balanced, the richness-resistance relationship was significantly positive while the richness-resilience relationship was negative. In contrast, if positive and negative interaction were unbalanced, the richness-resistance relationship was significantly negative while the richness-resilience relationship was positive.

A substantial body of evidence sustains that biodiversity enhances ecological stability in changing environments, but the underlying mechanisms in intact natural forest ecosystems remain unresolved. Using data from seven permanent plots, we test the influence and driving factors of plant diversity on stability and variability of diameter at breast height (DBH). We show that species richness under different soils and climate variability indirectly increases stability by species asynchrony rather than a direct influence. Beta diversity (plant species composition dissimilarities over time) has a strong positive effect on stability and soils indirectly increase stability by beta diversity. Soils and climate variability cause a larger effect on variation in standard deviation of DBH by species richness, beta diversity and species asynchrony relative to mean DBH. The study provides a new insight into how plant species diversity affects the process of ecosystem stability under various soil conditions and climatic variability.