LTREB: Woody Seedling Dynamics in a Wet Tropical Forest: Mechanisms of Species Co-existence

Michigan State University, East Lansing MI

Investigators

Abstract

A major challenge in ecology is to understand what determines the number and relative abundance of plant species in natural communities. This challenge is especially daunting in wet tropical forests, which harbor the highest species diversity of any ecosystem in the world. The seedling phase of a plant's life cycle is especially sensitive to pathogens and to the availability of light, nutrients, and water. What happens during this critical stage impresses a signature on forest species composition, from the understory to the canopy. Trees can live for much longer than humans and the dynamics of forests play out over even longer time scales; therefore, long-term data collection is necessary to capture important events that would be missed by short-term studies (e.g., seed production may occur every 12 years for some species). This proposal will extend an ~8 year record of seedling surveys in five forest stands in Costa Rica, with the goal of developing forest models of critical aspects of forest regeneration (seedling production, dispersion, growth and mortality) in response to light, soil fertility, and natural enemies. A better understanding of the factors that govern the relative abundance of tree species will aid in predicting forest responses to human influences, including the deposition of nitrogen, sulfur, and other chemical pollutants from the atmosphere. Furthermore, in tropical areas, exotic tree species often are used for reforestation because the regeneration requirements of native species are not well known, a knowledge gap that this research will help remedy. As part of this project, K-6 students will be growing plants in Michigan to learn about ecological processes that operate in all terrestrial ecosystems (from agricultural fields to wet tropical forest). Research results, data, and on-line identification tools will be shared with the public and other scientists through a project website.