THE FIRST 5 YEARS IN THE REORGANIZATION OF ABOVEGROUND BIOMASS AND NUTRIENT USE FOLLOWING HURRICANE HUGO IN THE BISLEY EXPERIMENTAL WATERSHEDS, LUQUILLO EXPERIMENTAL FOREST, PUERTO-RICO

Five years after Hurricane Hugo reduced the aboveground biomass by 50 percent in two forested watersheds in the Luquillo Experimental Forest of Puerto Rico, regeneration and growth of survivors had increased th e aboveground biomass to 86 percent of the pre-hurricane value. Over t he 5 yr, the net aboveground productivity averaged 21.6 Mg . ha(-1). y r(-1) and was faster than most plantations and secondary forests in th e area. Woodfall and associated nutrient fluxes never attained pre-sto rm values bur by the fifth yr, mean daily coral litterfall, and N, P, K, Ca, and fluxes in litterfall were 83, 74, 62, 98, 75, and 81 percen t of their pre-disturbance values, respectively. Aboveground nutrient pools of these nutrients ranged from 102 to 161 percent of their pre-d isturbance values and were larger after 5 yr because of higher nutrien t concentrations in the regeneration compared to the older wood that i t replaced. The following sequence of ecosystem reorganization during this first 5 yr period is suggested. An initial period of foliage prod uction and crown development occurred as hurricane survivors re-leafed and herbaceous vegetation and woody regeneration became established. During this period, 75 to 92 percent of the nutrient uptake was retain ed in the aboveground vegetation and there was a relatively low rate o f aboveground carbon accumulation per mole of nutrient cycled. This in itial period of canopy development was followed by a peak in abovegrou nd productivity that occurred as early successional species entered th e sapling and pole stages. This period was followed by the establishme nt of the litterfall nutrient cycle and an increase in the net product ivity per mole of nutrient cycled. During this 5 yr period, the Bisley Forest had some of the lowest within-stand nutrient-use-efficiencies and some of the highest levels of aboveground productivity ever observ ed in the LEE The study demonstrates char high levels of productivity and rapid rates of aboveground reorganization can be achieved with rap id within-system cycling and inefficient within-stand nutrient use.