XVI International Botanical Congess

Tree species diversity in seasonally flooded forests (SFF's) has been explained by species ability to tolerate flooding. Comparing flooding tolerance for seedlings of Prioria copaifera, a flood tolerant species, and three terra firme species, we concluded that flooding did not severely impair plant performance (i.e. growth and photosynthesis) on two out of the three terra firme species. Nonetheless, flooding caused a 25% reduction in root depth for seedlings of Prioria, while seedlings of terra firme species showed a 60% decrease. We propose that it is flooding followed by drought rather than flooding alone that determines species diversity in SFF's. To test this idea we followed mortality along with water stress in a cohort of 700 Prioria seedlings in a SFF in Panama and found greater seedling mortality during the dry season.