Coexistence of tropical tree species

摘要

For decades, ecologists have struggled to explain how so many tropical tree species can coexist. Kelly and Bowler propose that differences in recruitment fluctuation and competitive abilities among closely related tree species could promote coexistence, and data from a tropical deciduous forest in western Mexico seem to confirm their predictions. We argue, however, that the tests of their model's predictions make fundamentally flawed assumptions about both size―age relationships in trees and the factors that influence population size structures. As such, their results are potentially misleading and lack the necessary rigour to "reject all other theories of coexistence". Kelly and Bowler's model of species coexistence predicts that rare species should exhibit greater deviation in recruitment than common species. To test this, they compared differences between expected and observed age-class distributions for ecologically similar congeners. In essence, they predicted that abundant species should show fewer deviations in historical recruitment trends, and thus have 'smoother' age-class distributions.