Long-Term Response of Caribbean Palm Forests to Hurricanes
Ariel E. Lugo1,* and Jorge L. Frangi2
1International Institute of Tropical Forestry, Calle Ceiba 1201, Jardín Botánico Sur, Río Piedras, PR 00926-1119, USA. 2LISEA, Facultad de Ciencias Naturales y Museo-Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de la Plata, 1900 La Plata, Argentina. *Corresponding author.
Caribbean Naturalist, Special Issue No. 1 (2016)
We studied the response of Prestoea montana (Sierra Palm, herefter Palm) brakes and a Palm floodplain forest to hurricanes in the Luquillo Experimental Forest in Puerto Rico. Over a span of 78 years, 3 hurricanes passed over the study sites for which we have 64 years of measurements for Palm brakes and 20 years for the Palm floodplain forest. For each stand, species composition, species density, basal area, tree density, rates of tree ingrowth and mortality, and importance value of tree species were assessed. We also estimated stand and Palm population aboveground biomass for the Palm floodplain forest. We found that different forest attributes such as basal area and tree density exhibited different temporal response patterns to hurricanes. The passing of 2 hurricanes in less than 10 years shifted the forest-response pattern of Palm brakes into a different trajectory with wider oscillations than before the 1989 hurricane. Neither Palm forest type reached steady state during the period of observation. Palm brakes spent about 50 of 64 years of the study in a transition state, and during the last 14 of those years, Cecropia schreberiana (Yagrumo) displaced the Palms as the species with the highest importance value, likely due to hurricane effects. The Palm floodplain forest remained in a transition mode over the 20-year span of the study. The results of the study showed that stands located on the leeward of hurricanes experienced less structural and species-composition changes and had more time to recover from hurricane effects than those exposed to the windward path of the hurricane. Caribbean Palm forests are dynamic systems whose structure, species composition, species density, and processes are finely coupled to frequency and intensity of hurricanes. Because Palm forest dynamics are closely tied to hurricanes, it is possible to anticipate that any future change in the frequency or intensity of hurricanes is likely to influence these forest attributes, including species ranking by importance value.