Disturbance and Canopy Structure

In Two Tropical Forests

Brokaw, N., S. Fraver, J.S. Grear, J. Thompson, J.K. Zimmerman, E.M. Everham III, R. Waide, S.P. Hubbell, and R.B. Foster. Disturbance and canopy structure in two Tropical forests. In E. Losos and E. Leigh Jr. (eds.) Forest Diversity and Dynamism. The University of Chicago Press. In Press.

Abstract: Variation in tropical forest architecture reflects many site and historical factors. Similar studies at El Verde, Puerto Rico, and Barro Colorado Island, Panama, provide an opportunity to compare forest canopy surfaces and treefall gap variables between two tropical locations. Before Hurricane Hugo struck the forest at El Verde in 1988, its upper canopy surface was relatively smooth, and its gaps were few and small, compared to Barry Colorado. After Hugh, El Verde’s canopy appeared to be recovering its previous structure. We suggest that chronic hurricanes limit the size of trees, prevent individual trees from emerging above the main canopy, and cause pulses of treefalls at El Verde, all of which leads to a relatively smooth canopy and reduces the size and number of gaps between major storms. We discuss additional factors, including human disturbances at El Verde, that also influence the canopy structure of these and other forests. A projected increase in the number and intensity of tropical cyclonic storms could significantly alter canopy structure of some forests.