XVI International Botanical Congess

How important is edaphic hetereogeneity in determining the local distribution of tropical rain forest trees? We addressed this question over a mesoscale landscape, a 600 ha area of old-growth tropical lowland rain forest at the La Selva Biological Station, Costa Rica. We determined the edaphic background and tree species distributions using systematic sampling based on a 100 x 50 m grid system. At 1170 grid intersection we measured and identified all trees >10 cm diameter in a 0.01 ha plot and took soil samples stratified by depth. Many and perhaps most tree species at this site show clear edaphic preferences over a relatively small range of variation in upland soil characteristics. We will discuss the implications of these findings for understanding and conserving tropical rain forests.