DAMAGE AND RESPONSIVENESS OF JAMAICAN MONTANE TREE SPECIES AFTER DISTURBANCE BY A HURRICANE

A severe hurricane affected Jamaican montane rain forests in 1988. We made local and widespread measurements of tree condition in three periods: prehurricane 1974-1984 (preh.); hurricane 1984-1989 (h.); and post-hurricane 1989-1992 (post-h.). In the h. period, 7.22% of stems and 4.72% of the total basal area died; crown loss was the most frequent cause of mortality. Among individual tree species, the hurricane caused a large range in mortality (0-26%) and non-fatal damage. Post-h. mortality was greater than mortality in the h. period, and varied among species. Post-h. stem growth rates (all species combined) were more than double the prehurricane rates, but species showed a considerable range from no significant increase to eight times greater. We classified 20 common tree species using damage scores (normalized h. mortality, plus normalized change in mortality from preh. to post-h., plus normalized complete crown loss in h.) and response scores (normalized change, preh. to post-h., in recruitment to the greater than or equal to 3 cm dbh size class, plus normalized change in growth rate from preh. to post-h., plus normalized frequency of sprouts). Species were assigned to one of four groups: resistant (11 species), with low damage and low response; susceptible (5 species), with high damage and low response; resilient(1 species), with high damage and high response; and usurpers (3 species), with low damage and high responsiveness. The grouping of species was broadly related to their regeneration requirements. Most species with seedlings usually found under closed canopy were resistant; three of the four species with seedlings usually found on landslides were also resistant. Species with seedlings most frequently found in gaps included resilient, susceptible, and usurper species, but were not usually resistant. It is likely that the three species classified as usurpers will increase their relative abundance in the forest in the next decades and that Cyathea pubescens, which was very susceptible, will decrease in relative abundance of adults. Most of the other species are likely to have small changes in their relative abundances. Thus, at present, hurricanes have few long-term effects on the forests, although a change in the disturbance regime may alter this.