SUMMARY OF ECOSYSTEM-LEVEL EFFECTS OF CARIBBEAN HURRICANES

Effects of Hurricane Hugo on forest ecosystem processes in Puerto Rico and South Carolina are summarized from six research papers presented in this issue. Hurricanes are major catastrophic disturbances capable of altering ecosystem-level processes in both the short and the long term. The high intensity, broad scale, and relatively high frequency of these storms makes them a major agent of catastrophic disturbance in the Caribbean and the Atlantic seaboard of the U.S.A. (Scarena & Larsen 1991). Although the return frequency of hurricanes for any given area is low (on the order of years or decades; Fig. 2 in Walker et al. 1991) relative to the lifespan of an individual investigator or a typical research project, the return time is shorter than the life span of a canopy tree or a forest ecosystem. Hurricanes have struck the Caribbean repeatedly within recorded history (Scatena & Larsen 1991, Walker et al. 1991), and have surely played a role in shaping plant population dynamics (e.g., Lugo et al. 1983), soil development (Scatena & Larsen 1991) and nutrient cycling (Sanford et al. 1991) over evolutionary time scales (thousands of years) in much of the Caribbean. Out paper summarizes the six preceding research papers in this issue, and focuses on the short-term changes in nutrient cycling induced by Hurricane Hugo, as well as the possible long-term consequences of such disturbances on tropical forests. Data on biomass and nutrient fluxes caused by Hurricane Gilbert in Quintana Roo, Mexico (Whigham et al. 1991, Plant Section, this issue) are included, but the discussion is primarily focused on two Long-Term Ecological Research sites funded by the National Science Foundation: the Luquillo Experimental Forest (LEF) in Puerto Rico and the North Inler site in South Carolina. The processes summarized below are: hurricane litterfall and associated nutrient fluxes and exports; salinization of coastal soils from storm surge and associated changes in soil chemistry; fine root dynamics after disturbance; changes in soil nutrient pools and fertility; and, hurricane-induced changes in nitrogen (N) transformations and fluxes.