Dissertation Research: Recruitment in a Large-Seeded Tropical Tree

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9321553 lLevey Plant recruitment is the process by which plants produce offspring (seeds) to replace themselves and thus produce a self- regenerating habitat. Seed dispersal is the process that allows plants to "move" by distributing the seeds throughout the surrounding area. Most plants produce many more seeds than can survive because after dispersal, mice and other rodents eat (and therefore kill) many of the seeds. Sometimes, if seeds are abundant, rodents may store some extra seeds to be eaten later in the year. A few of these stored seeds may be forgotten and may germinate, in which case the rodents are acting as "secondary" dispersers. Those seeds that survive and germinate face many other dangers, such as plant-eating insects and mammals, mold and disease, and falling branches and trees. Thus, plant recruitment is a complicated process of many stages and involves interactions with many other species. In tropical forests, which are being rapidly destroyed, we know very little about plant recruitment, and therefore we lack the information necessary to make recommendations about how to save and restore these forests.%%% Ocotea endresiana (related to avocados) is a common tree in the mountain forests near Monteverde, Costa Rica. The large fruits are eaten and the seeds dispersed by relatively few species of birds. Despite several studies on seeds dispersal of some related trees, the post-dispersal fate of these seeds is not well understood. In this study, recruitment of O.endresiana seedings will be examined to determine the importance of primary dispersal, secondary dispersal, and seed predation on seedling establishment.%%% This research will provide some of the first information on the degree of complexity involved in the seed dispersal process. Such information will prove useful to wildlife managers who hope to rebuild -- or even simply to maintain -- natural habitats. The interrelationships among a complex array of seed dispers ers and predators will be examined. Each one plays a role in determining plant survival -- the question is, how critical is that role? If the roles of various primary and secondary dispersers are known, then one can predict the effects of animal extinctions on seed dispersal. Increasing knowledge of seed dispersal and plant recruitment will provide another piece in the puzzle of understanding how tropical forests "work."***