PARENT SESSION
Oral Session #64: Plant Population Ecology.
Presiding: S. Collins
Wednesday, August 7. 1:00 PM to 4:45 PM. Gila Meeting Room, TCC.

Directed dispersal effects on landscape-level demographics of a neotropical tree.

King, Rachel^*,1, ¹ University of Miami, Coral Gables, FL

ABSTRACT- River meanders generate a spatially explicit dynamic landscape of forest patches of differing successional states and topography, in contrast to more well-known, time-dependent landscape of patches generated by treefall gap-phase regeneration. River meander microhabitats that differ in their suitability for plant recruitment are arranged in a relatively predictable pattern, such that seed dispersal biased toward one direction relative to the river might represent directed dispersal. To investigate the effect of differing dispersal patterns on a floodplain tree, I studied the demographics of Calophyllum brasiliense, a large seeded bat dispersed timber tree found mostly in seasonally flooded depressions of mid-successional floodplain forest, in 10 plots at Cocha Cashu biological station in Manu National Park, Peru. At this site, C. brasiliense seeds are dispersed by large frugivorous bats that carry the fruits to feeding roosts overhanging open ground, where conditions for tree recruitment may be ideal for these species. Seedling survival and growth, as well as growth of sapling and juvenile stages were highest in early successional habitat, while trees large enough to produce fruit were only found in mid-successional and mature forest. To compare the effects of differing dispersal patterns on landscape-level population growth rate I modeled habitat specific demographics within a landscape where successional stages are regularly patterned (as they are in river meanders). Dispersal directed towards the river increased landscape-level population growth rate only at low dispersal rates.

KEY WORDS: seed dispersal, demography, frugivorous bats, neotropics