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.

Increasing studies have shown the importance of intraspecific trait variation (ITV) on the ecological process. However, the patterns and sources of ITV are still unclear, especially in the propagule of coastal vegetation. Here, we measured fresh weight (FW), fresh length (FL), maximum transverse diameter (TDmax), minimum transverse diameter (TDmin) and the ratio of TDmax to TDmin (RTD) of the hypocotyl (propagule) of Kandelia obovata for 66 genealogies across 26 sites. By combining multiple factors of climate, ocean and maternal tree to analyze their effects on the intraspecific trait variation of mangrove hypocotyl. The results showed that value of establishment traits (FW, FL, TDmax and TDmin which are related to mass) decreased along increasing latitudinal gradients and they were directly positively regulated by temperature. ITV of dispersal trait (RTD) was unstructured along latitudinal gradients, which was constrained by fitness tradeoff. Our findings indicate that establishment traits mainly varied between populations, whereas dispersal traits mainly varied between individuals. This study provides insights into the ITV of propagule in different functional dimensions on a broad scale and that may help integrate ITV into future analyses of mangrove protection.