Impact of Herbivores on a Costa Rican Deciduous Forest

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This is a proposal to continue research in the tropics by one of the, if not the world's, premier tropical ecologists, Professor Daniel Janzen. This is an expanding basic research program on animal-plant interactions in the tropical, dry forests of Santa Rosa National Park in northwestern Guanacaste Province, Costa Rica, with the results being applied directly to the problem of dry forest ecological and biocultural restoration (as well as being published and popularized in traditional ways). Observations and field experiments will be conducted on: 1. Demography and seed predator specificity of Liomys salvini (spiny pocket mice). 2. Host-specificity (in the wild) of the 3100-plus species of caterpillers. 3. Host-specificity of the parasitoid wasps and flies supported by the wild Lepidoptera fauna. 4. Species composition of the caterpillars brought to the nestlings of medium-sized birds. 5. Differential food processing by caterpillars feeding on potentially toxic plants versus those feeding on plants rich in potential inhibitors. 6. Seed production biology of the trees Hymenoea courbaril, cyclocarpum, Dioclea megacarpa and Ateleia herbert-smithii. 7. Invasion of pastures, old fields, tree falls and landslides by dry forest trees. 8. Brief studies: wood increment rates and aging (by growth rings) of the tree H. courbaril and E. cyclorcarpum, migration of fruit- and flower-visiting moths in and out of Santa Rosa, dormancy of moth pupae and large tree seeds, detailed phenology of fruit drop by trees with seeds dispersed by ground-based large herbivores, use of seasonal changes as cues by insects, escape behavior of large caterpillars, impact of defoliation on fruit crop production, termination of caterpillar outbreaks, and caterpillar survivorship in the wild. At a time when tropical areas are being brutally deforested, this research is of paramount importance. It stimulated and continues to stimulate generations of tropical ecologists and is of scientific and practical value in and of itself. The Ecology Program of the NSF is pleased to support the research.