Print PageTropical communities are renowned for their biodiversity. Not only is there an elevated level of species diversity within communities (i.e. alpha diversity) with respect to less diverse temperate communities, but species turnover between tropical communities (i.e. beta diversity) is also elevated. Perhaps, nowhere are patterns of tropical diversity more often documented than in tree communities, yet a substantial debate still exists on the extent to which the observed patterns of species alpha and beta diversity are the result of deterministic or stochastic processes and whether the strength of these processes may vary across latitude. Here we argue that understanding the degree to which patterns of diversity across latitude are the result of deterministic or stochastic processes is substantially enhanced by quantifying the phylogenetic and functional similarity of species. We demonstrate this by quantifying the phylogenetic and functional beta diversity of trees using seven forest inventory plots arrayed along a latitudinal gradient. Specifically, the work quantifies whether phylogenetic and functional beta diversity is higher or lower than expected given the species beta diversity.
Results/Conclusions
The results show that species turnover through space in these forests is often non-random with respect to phylogeny with higher than expected phylogenetic turnover often occurring in tropical latitudes and lower than expected turnover in most forests particularly in temperate latitudes. The results largely support a deterministic model of community assembly, but the relevant ecological processes inferred are not consistent across latitude.
