FOREST STRUCTURE BEFORE AND AFTER HURRICANE HUGO AT 3 ELEVATIONS IN THE LUQUILLO MOUNTAINS, PUERTO-RICO

Hurricane Hugo struck Puerto Rico on 18 September 1989 and radically altered the canopy structure of forests in the Luquillo Mountains. We measured canopy structure before and after the hurricane in hectare-sized plots of "tabonuco forest" (subtropical wet forest) at 350 m elevation, "colorado forest" (lower montane wet forest) at 750 m, and "cloud forest" (lower montane rain forest) at 1000 m. In all three plots the chief effect of the hurricane was to reduce significantly the vegetation cover in upper height intervals. Foliage profiles (showing percent vegetation cover in height intervals above ground) changed significantly, average maximum canopy height decreased (by as much as 50%), and the amount of low canopy area (vegetation less-than-or-equal-to 2 m high) markedly increased (up to 60-fold) in all three plots. In the colorado forest plot the hurricane caused more damage on ridges than in valleys; whereas, the cloud forest plot sustained equal damage on windward and leeward slopes. Overall, the hurricane altered forest structure so much that forest composition and dynamics could be affected for many years. Local variation in hurricane damage can contribute to forest complexity in the Luquillo Mountains.