The Interaction between Climate and Soil Properties Influences Tree Species Richness in Tropical and Subtropical Forests of Southern China

The climate and soil properties are major determinants of plant growth and forest community assembly across diverse biomes. However, the contribution of climate and soil on species diversity in tropical and subtropical forests remains controversial. Therefore, this study aims to evaluate the effects of soil and climate on tree species richness using survey data across 495 tropical and subtropical forest plots in Southern China. The selected predictors were categorized as local plot characteristics, climate, and soil factors, and their relationship with tree species richness was modeled using negative binomial generalized linear models. The results revealed that the considering of the interaction between climate and soil properties considerably improved the goodness-of-fit of these models. The individual effects of climate and soil factors had weak relationships with species richness, accounting for 3.61% and 5.77% of the overall 58.9% explained variance in species richness, respectively. Instead, the interaction between climate and soil properties explained most of the statistical variation in tree species richness (84.34% of the overall 58.9% explained variance). The results highlight the importance of soil and climate interactions on tree diversity in tropical and subtropical mature natural forests and their incorporation into biodiversity assessment models to enhance the prediction of community change and responses to climate change.