Selected Highlights of the Barro Colorado Island Forest Dynamics Project

We review results from the Barro Colorado Island (BCI) Forest Dynamics Plot, focusing on the relative importance of nonstabilizing demographic stochasticity (drift) and stabilizing deterministic processes on the diversity and dynamics of the BCI tree community. The evidence indicates involvement of both stochastic and deterministic processes. Drift plays a prominent role in the dynamics of rare and very rare species. Deterministic forces, including conspecific density dependence and environmental variance, cause changes, often large, in the abundances especially of common species. No abundance class or life history guild of species was immune from change; three-quarters of all species changed by >25% in total abundance between 1982 and 2015. These changes were not monotonic, and therefore were not successional. Most species exhibit patches of rapidly changing abundance in a matrix of slower changing abundances. These patches are uncorrelated with canopy gap disturbances. The dynamics are consistent with time-lagged interactions between tree hosts and their enemies, including pathogenic heart-rot fungi.