Relative roles of local disturbance, current climate and paleoclimate in determining phylogenetic and functional diversity in Chinese forests

The main processes underlying the generation and maintenance of biodiversity include both local factors such as competition and abiotic filtering and regional forces such as paleoclimate, speciation and dispersal. While the effects of regional and local drivers on species diversity are increasingly studied, their relative importance for other aspects of diversity, notably phylogenetic and functional diversity is so far little studied. Here, we link data from large Chinese forest plots to data on current and Last Glacial Maximum (LGM) climate as well as local disturbance regimes to study their relative roles in determining woody plant phylogenetic and functional diversity in this important hotspot for woody plant diversity. Local disturbance was the best predictor of functional diversity as represented by maximum canopy height (Hmax), probably reflecting the dominant role of competition for light in determining the forest Hmax structure. In contrast, the LGM–present anomaly in temperature was the factor with the strongest explanatory power for phylogenetic diversity, with modern climate also important. Hence, local contemporary and regional historical factors have highly contrasting importance for the geographic patterns of the functional (as represented by variation in maximum canopy height) and phylogenetic aspects of Chinese forest's woody plant diversity. Importantly, contemporary factors are of overriding importance for functional diversity, while paleoclimate has left a strong signature in the phylogenetic diversity patterns.