Both human and natural disturbance may play an important role in regulating the diversity of tree species in tropical forests. Clearing for agriculture represents one of the most common forms of human disturbance in the tropics, while hurricanes pose the greatest threat of natural disturbance for forests of the Caribbean. To investigate the relative importance of human and hurricane disturbance in tropical forests the investigators will conduct a census of the diameter, species and location of all trees in the 16 hectare Luquillo Forest Dynamics Plot (LFDP). The census results will be compared with previous censuses taken in 1990, 1995 and 2000. A portion of the LFDP was used for agriculture prior to 1934, and Hurricanes Hugo (1989) and Georges (1998) both caused considerable damage. Together, data from the four censuses will allow us to contrast tree population dynamics during intervals that have experienced very different patterns of hurricane disturbance, and for parts of the forest with different agricultural land use histories. We will develop new analyses of the census data, using likelihood methods to examine how the spatial configuration of trees within the forest and patterns of disturbance by hurricanes change the dynamics of the most common tree species. Future work will integrate our results using a forest simulation model.
The broader impacts of our research include contributing to the global network of tropical forest plots as part of the Center For Tropical Forest Science. This network has been central to the attempts of ecologists to understand the structure and function of tropical forests. Our research will also develop new methods for the analysis of long-term data in tropical forests - these methods can then be used more widely across the network. The project will provide research experience for a large number of undergraduate and particularly minority students in tropical ecology.
