Microenvironment and functional-trait context dependence predict alpine plant community dynamics

Predicting the structure and dynamics of communities is difficult. Approaches linking functional traits to niche boundaries, species co-occurrence and demography are promising, but have so far had limited success. We hypothesized that predictability in community ecology could be improved by incorporating more accurate measures of fine-scale environmental heterogeneity and the context-dependent function of traits. We tested these hypotheses using long term whole-community demography data from an alpine plant community in Colorado. Species distributions along microenvironmental gradients covaried with traits important for below-ground processes. Positive associations between species distributions across life stages could not be explained by abiotic microenvironment alone, consistent with facilitative processes. Rates of growth, survival, fecundity and recruitment were predicted by the direct and interactive effects of trait, microenvironment, macroenvironment and neighbourhood axes. Synthesis. Context-dependent interactions between multiple traits and microenvironmental axes are needed to predict fine-scale community structure and dynamics.