The Community-Level Consequences of Seed Dispersal Patterns

Because it lays the template from which communities develop, the pattern of dispersed seed is commonly believed to influence community structure. To test the validity of this notion, we evaluated theoretical and empirical work linking dispersal kernels to the relative abundance, distribution, dispersion, and coexistence of species. We found considerable theoretical evidence that seed dispersal affects species coexistence by slowing down exclusion through local dispersal and a competition-dispersal trade-off, yet empirical support was scant. Instead, most empirical investigations examined how dispersal affects species distribution and dispersion, subjects with little theory. This work also relied heavily on dispersal proxies and correlational analyses of community patterns, methods unable to exclude alternative hypotheses. Owing to the overall dichotomy between theory and empirical results, we argue that the importance of dispersal cannot be taken for granted. We conclude by advocating experiments that manipulate the seed dispersal pattern, and models that incorporate empirically documented dispersal kernels.