Seed dispersal of the tropical tree, Platypodium elegans, and the escape of its seedlings from fungal pathogens.

Seedlings of Platypodium elegans, a wind-dispersed tree on Barro Colorado Island, Panama, were monitored. Damping-off by fungi caused most mortality in the first 3 months, during which mortality occurred at an exponential rate. Both incidence and rate of damping-off were inversely correlated with distance of seedlings from the parent tree. Irrespective of density, a lower proportion of seedlings died from damping-off in light-gaps than in the shaded understory. After 1 yr a higher proportion and absolute number of seedlings survived at distances away from the parent; survival was highest in light-gaps. Fungal pathogens causing damping-off may increase selection for the dispersal of seeds away from the parent tree. They significantly increase the distance at which a parent's offspring are likely to survive the seedling stage and thus, ultimately, may influence tree spatial patterns and species diversity of the tropical forest. -from Author