Litterfall and Decomposition related data sets

PROJECT DESCRIPTION: Understanding the long-term impact of deforestation on ecosystem structure and function of tropical forests may aid in designing future conservation programs to preserve biodiversity and sustain ecosystem productivity. We examine forest structure, tree species composition, litterfall (fine and coarse) due to Hurricane Hugo and subsequent fine annual litterfall inputs, litterfall rate, and leaf litter decomposition.

The decomposition experiment was originally designed to examine short-term disappearance of folliage from three important mantane species: Prestoea montana (R. Grah. ) Nichols, Dacryodes excelsa (Vahl. ), and Cyrilla racemiflora. Hurricane Hugo (August, 1989) provided a unique opportunity to study effects of this type of natural disturbance on decomposition. With some modifications study was repeated in 1990 with some changes in the design which allowed for comparisons of short -term foliar litter biomass and nitrogen dynamics: (1) among the three species, (between the colorado and tabonuco forest types, (3) between riparian and upland sites, and (4) between pre- and post-hurricane environments.

History of litterfall and decomposition studies (MRCE experiment) at the Luquillo Experimental Forest (LEF)

The Minority Research Centers of Excellence (MRCE) experiment was designed originally to determine whether forest productivity was limited by nutrient availability, genetic constraints or climatic variables along a steep environmental gradient in the Luquillo Mountains of Puerto Rico. Comparisons were made between dwarf forest at 500 m elev. and tabonuco forest from 300-400 m elev. There were two main experiments in the original design: 1) forest fertilization (complete versus none); 2) transplant experiments using common gardens at high and low elevation, with and without wind protection at high elevation. In addition, phenology of leaves was studied in the dwarf forest to determine the longevity of leaves in the canopy. The occurrence of Hurricane Hugo in September 1989, just as the forest plot fertilization experiments were to begin, neccesitated the addition of a hurricane debris-removal treatment as a second type of control in the lower elevation tabonuco forest. The hurricane also changed the nature of the study into one of looking at changes in forest composition and the recovery of forest productivity in response to fertilization and hurricane debris-removal. Seedling, sapling, herbaceous plant, and fern responses, as well as measurements of light availability and canopy closure were added to the originally planned measurements of tree diameter growth, leaf litter production, and fine root production and turnover. Another hurricane in 1998 (Hurricane Georges) presented an opportunity to look at the effects of removing only the woody debris (in new plots) versus removing all hurricane debris.

Funding for continued studies of the MRCE plots ended in 1998, but they were of such great value as a long-term experiment that they were incorporated into the LTER program.