Offspring Recruitment around Tropical Trees: Changes in Cohort Distance with Time

The spatial pattern of dispersed seeds and subsequent mortality of offspring over time determine recruitment distance relative to the parent tree. For isolated parents of the tropical tree, Platypodium elegans J. Vogel (Leguminosae), high seedling mortality nearer the parent tree due to fungal pathogens caused the median distance of surviving 3-month old seedlings to be greater than that of germinated seeds. After one year the median distance of surviving offspring either increased further or decreased, depending on the location of light-gaps, in which survival and growth were greatly enhanced. Saplings were further from the parent than either dispersed seeds or 1-yr old seedlings. Thus recruitment distances of a given cohort were not constant through time. Mortality distributed uniformly in space or between individuals does not cause a shift in the location of recruitment. Any observed shift is an indication of densityor distance-dependent mortality. The results demonstrate the potential importance of fungal pathogens and light-gaps as factors contributing to the distribution of offspring of these adult trees.