High seed dispersal rates in faunally intact tropical rain forest: theoretical and conservation implications

Dispersal limitation may promote high tree-species diversity in rain forest by slowing local competitive exclusion, but evidence is scarce. By compari ng the species lists of tree plots with those of nested seedling plots in r ain forest at Gunung Palung, we found that the proportion of local seedling s arising from active dispersal events (via wind or animals, but not simply dropped from parent trees) was high: 68% of species and 46% of the individ ual seedlings. Local seedling species richness was not limited by the local richness of adults. Using these data, a spatially explicit simulation mode l indicated that dispersal limitation may not contribute substantially to t he maintenance of tree diversity in this forest. We predict that the loss o f animal seed dispersers would reduce local species richness of seedlings b y 60%. While this reduction could possibly increase the influence of disper sal limitation, it would interfere with other mechanisms maintaining divers ity.