Community stability of woody plants among six natural forests under contrasting environmental conditions

Community stability of woody plants reveals how forest ecosystems respond to global change over time. However, its macroecological patterns and underlying mechanisms across contrasting environments remain poorly understood. Here, using an unprecedented dataset comprising ∼1.9 million tree measurements of 1,013 species collected over ten years across temperate, subtropical, and tropical forests, we investigated broad-scale patterns of temporal stability and their underlying mechanisms. Linear mixed models and piecewise structural equation models were used to disentangle the effects of climate, biotic and abiotic factors on community stability. Our results revealed a significant negative relationship between integrated climatic gradient (ClimatePCA1) and species stability, with higher ClimatePCA1 values indicating warmer and wetter conditions, as well as greater interannual variability in potential evapotranspiration and annual precipitation. By contrast, we detected no significant relationships between climate and between community stability and either species asynchrony. Both species asynchrony and species stability were positively associated with community stability, whereas species richness showed a negative relationship with community stability. Further analyses indicated that biotic (species richness, species asynchrony, species stability, stem abundance and functional trait composition) and abiotic (climate, soil conditions) factors jointly regulated community stability, with species asynchrony and species stability emerging as the strongest predictors. However, the relative contributions of species asynchrony and species stability to community stability were not mediated by climatic conditions. Our results highlight the crucial role of stabilizing mechanisms in determining community stability, suggesting that conserving species richness alone may not be sufficient for stabilizing naturally-assembled forests.