The Dynamics of a Neotropical Forest: The Year 2000 Recensus

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

9909947 Hubbell The Barro Colorado Island (BCI) Forest Dynamics Project is the longest running large-scale study in the world of a tropical forest, established to test competing theories at the population and whole community level for the maintenance of high tree species diversity in tropical moist forests. The BCI study is the flagship project and model for a global network of similar plots established since 1980 throughout the New and Old World tropics. Current activities are to conduct the fifth complete census of the 50 ha plot on BCI in the year 2000, extending the study to two decades. The goals of the fifth census are (1) to update the data on recruitment, growth, and survival of all woody plants >1 cm dbh (>240,000 stems) in the plot since the last census 5 years ago, (2) to extend the census to smaller sapling size classes; (3) to analyze the fate of all trees (growth, survival) as a function of their local biotic neighborhood, and (4) to use this neighborhood analysis and other information to develop a first-generation dynamical model of the BCI forest. Understanding these local neighborhood effects is essential for developing a predictive theory of canopy tree replacement, which in turn is critical for understanding how tree species diversity is maintained in the BCI forest. A preliminary neighborhood analyses on the 13-year survival of 230,000 individual plants through the last census has been completed. There were significant, often strong, neighborhood effects on focal plant survival. The effects of four neighborhood factors were analyzed: the number of neighbors of the same species as the focal plant, the number of neighbors surviving from the first to the last census irrespective of species, the size of the focal plant relative to its neighbors, and the number of species among the focal plant's neighbors. The results, if borne out by additional data from the next census have important implications for understanding the factors that lead to high tree species diversity in tropical forest communities.