SEEDLING RECRUITMENT PATTERNS IN A BELIZEAN MANGROVE FOREST - EFFECTSOF ESTABLISHMENT ABILITY AND PHYSICOCHEMICAL FACTORS

A field study was conducted to evaluate the relative importance of fac tors affecting seedling establishment and survival on a mangrove-domin ated island in Belize. An examination of spatial patterns of seedling relative densities in relation to reproductive adults and physico-chem ical conditions provided correlative information on factors affecting mangrove regeneration patterns. Distance from reproductive adults expl ained 89-94% of the variation in relative density of Rhizophora mangle seedlings, whereas availability of resources (light and NH,) explaine d 73-80% of variation in Avicennia germinans seedling relative density . Just after dispersal (December), 89% of the variation in Lagunculari n racemosa seedling relative density was attributable to distance from reproductive adults, but 7 months later (July) 74% of the variation w as explained by intensity of flooding- and salinity-related stresses. Survivorship (after 2.5 years) of propagules and seedlings of R. mangl e and A. germinans transplanted to zones of contrasting physico-chemic al conditions demonstrated that: (1) mortality was highest during the establishment phase and major causes were failure to strand before via bility was lost, consumption by predators and desiccation; and (2) aft er establishment, differences in sensitivity to physicochemical stress factors such as flooding (A. germinans) and initial orientation of th e seedling axis (R. mangle) exerted a further influence on seedling su rvival. The results indicate that seedling recruitment in these neotro pical forests is strongly influenced by dispersal patterns, differenti al establishment abilities and effects of physico-chemical factors tha t vary with elevation and distance from the shoreline.