Life-history dimensions indicate non-random assembly processes in tropical island tree communities

Community assembly processes on islands are often non-random. The mechanisms behind non-random assembly, however, are generally difficult to disentangle. Functional diversity in combination with a null model approach that accounts for differences in species richness among islands can be used to test for non-random assembly processes, but has been applied rarely to island communities. By linking functional diversity of trees on islands with a null model approach, we bridge this gap and test for the role of stochastic vs. non-random trait-mediated assembly processes in shaping communities by studying functional diversity-area relationships. We measured 11 plant functional traits linked to species dispersal and resource acquisition strategies of 57 tree species on 40 tropical islands. We grouped traits into four life-history dimensions representing (i) dispersal ability, (ii) growth strategy, (iii) light acquisition, and (iv) nutrient acquisition. To test for non-random assembly processes,...