Species-habitat associations and demographic rates of forest trees

Niche-driven effects on demographic processes generated in response to habitat heterogeneity partly shape local distributions of species. Thus, tree distributions are commonly studied in relation to habitat conditions to understand how niche differentiation contributes to species coexistence in forest communities. Many such studies implicitly assume that local abundance reflects habitat suitability, and that abundance is relatively stable over time. We compared models based on abundance with those based on demographic performance for making inferences about habitat association for 287 tree species from three large dynamic plots located in tropical, subtropical and temperate forests. The correlation between the predictions of the abundance-based models and the demography-based models varied widely, with correlation coefficients ranging nearly from -1 to 1. This suggests that the two types of models capture different information about species-habitat associations. Demography-based models evaluate habitat quality by focusing on population processes and thus should be preferred for understanding responses of tree species to habitat conditions, especially when habitat conditions are changing and species-habitat interactions cannot be considered to be at equilibrium.