HURRICANE DAMAGE TO A FLOOD-PLAIN FOREST IN THE LUQUILLO MOUNTAINS OF PUERTO-RICO

Hurricane Hugo caused low to moderate damage to a flood plain forest that was partially protected by its topographic position. Treefalls and the location of damage suggested N to NW wind direction during the storm. Thirty percent of the trees, or 693 trees/ha, had some damage and 84 percent of the damage was to the canopy. Most of the damage to trees was caused by direct wind impact (83%) as opposed to secondary effects (16%). Over 80 percent of the snapped, leaning, and uprooted trees were dicotyledonous. Tree mortality was only 1 percent, and most of the damage to the sierra palm Prestoea montana (R. Grah.) Nichols was loss of leaves. Rapid refoliation, epicormic branching, adventitious root production, resprouting, and regeneration from seed in open areas were observed nine months after the event. Ten percent of the aboveground biomass and 12-16 percent of the nutrient stocks (N, P, K, Ca, Mg) were transferred to the forest floor, mostly in the form of woody biomass and nutrient-rich leaves. Palm leaves were the dominant leaf component of necromass. Instantaneous in situ fine and coarse necromass production was 10 and 9.2 Mg/ha, respectively. Net changes in aboveground mass, N, P, K, Ca, and Mg (in percent of prehurricane value) were 8, 3, 0, 3, 12, and 1, respectively, in spite of a high rate of loss by export. The source of additional mass and nutrients were holes from upland forests that fell into and remained inside the flood plain.