| Tropical forests are besieged by local farmers and ranchers, by development programs of national governments, and by international logging and mining companies. What remains as tropical forest in 50 or 100 years, and what regenerates as forest 500 years from now will depend not only on the ability of conservationists and resource managers to hold the developers at bay, but also on how well we understand the biological, ecological, and evolutionary processes that are affecting the remnant forests. This thesis examines the reproductive fate of a self-incompatible, insect-pollinated, tropical tree species, Tabebuia rosea (Bignoniaceae) in forest fragments. To address the regenerative ability of this species in forest fragments, I investigated the flowering phenology, cross-compatibility, visitation rates by bee pollinators, pollen deposition rates, fruit and seed production, early seedling growth, and genetic diversity of T. rosea in fragmented forests and compared these results to edge and interior forests.; In Chapter 1, I demonstrated that individuals of Tabebuia rosea in forest fragments begin flowering before trees in interior forest and reach peak flowering earlier. In Chapter 2, I found that crosses between individuals within the same fragment were unsuccessful in producing mature seed and that seedlings produced by nearby pollen were more robust than seedlings produced by far pollen. In Chapter 3, I found no difference in the total number of bees visiting per receptive flower among the three habitats, however, significantly less pollen per flower was delivered to fragment trees than to edge trees. In Chapter 4, I found a reduction of genetic diversity and a loss of rare alleles from seedlings from forest fragments. Further, I demonstrated that fragment seedlings were significantly smaller and had significantly fewer leaves than interior seedlings.; Demonstrating these differences for a species like Tabebuia rosea is particularly significant in understanding the ramifications of forest fragmentation because this species should do well in habitat fragments. Other species, less tolerant of windy, high-light conditions, could experience greater reductions in fecundity and genetic diversity. How many species are lost from fragments will depend on our ability to maintain many large forest patches in the landscape matrix. |
