Seed dispersal by bats and the population dynamics of a canopy tree, Calophyllum brasiliense (Clusiaceae), in an Amazonian river meander forest

This study focuses on the effects of seed dispersal by bats and river meander succession on the population dynamics of Calophyllum brashense (Clusiaceae), a flood tolerant timber tree in the Manu Biosphere reserve of Peru. In lowland tropical rainforests, river meanders generate a spatially dynamic landscape of forest patches of different successional states and elevations. Here I present three related studies that address: (1) the establishment requirements of C. brasiliense in the river meander successional habitats, (2) predicting the conditions under which directed dispersal would be required to maintain the species on the landscape using a habitat-stage matrix model of the population dynamics of C. brasiliense in the river meander dynamic landscape, and (3) the seed deposition pattern created by frugivorous bats for C. brasiliense. I investigated the effects of successional stage and microelevation on seedling establishment of C. brasiliense in a fully crossed experimental design of seeds planted in three successional stages (early, mid, and mature) and two microelevations (levees and backwaters). Seedling establishment success in this study was affected by both successional stage and microelevation, but microelevation was mostly important in mid-successional habitats. In general, seedlings in early succession experienced better conditions than in mature forest; light levels and seedling growth were higher and herbivory was lower. In mid-successional habitat, microelevation determined habitat dispersal rates, persistence requires dispersal directed toward early succession.; I trapped and radio-tracked bats near fruiting C. brasiliense to determine which species remove fruit, and how far they disperse seeds. I censused feeding roosts to estimate minimum dispersal distances from adult trees. Results show bats can move C. brasiliense fruits up to 500 meters. Feeding roost density was lower in early succession than in other habitats, but because no C. brasiliense fruit was produced there, that any seeds were taken to early succession indicates that dispersal by bats is important in this habitat. I hypothesize that maintenance of C. brasiliense in the Manu river meander system requires dispersal to early successional habitat, and that dispersal is provided by large frugivorous bats.