Hurricanes are disturbances that in forests result in canopy opening, fallen trees and leaves which accumulate on the ground and in turn alter physicochemical characteristics of this habitat, as well as, decomposer activity and nutrient fluxes. Litter decomposition depends primarily on the interaction among climate, litter quality and biota, as a consequence any change in habitat may produce micro variations in these factors which in turn affect decomposition. Our objective is to evaluate the effects that hurricane driven changes in forests produce on green litter decomposition, decomposer communities and nutrient mineralization. This study is part of the Canopy Trimming Experiment 2 performed by the Luquillo LTER at El Verde Field Station, Puerto Rico. For this, three blocks (A, B and C) were selected, in each block two 20m x 20m plots were located, one plot was control and one Canopy opening + debris deposition (Trim+Debris). Each plot was subdivided into 16 sub-plots, from which three sub-plots (5m x 5m) were randomly selected. In each subplot, litterbags with different mesh sizes were placed. This experimental design represents 3 blocks x 2 plots/block (1 trim/ 1 control) x 3 subplots x 3 litterbag mesh sizes x 4 collecting times, for a total of 216 litterbags. Each of these litterbags were used as the sampling unit. In each one, decomposer fauna and nutrients were measured. Decomposer fauna were retrieved using Berlese Funnels and mineralized nutrients were quantified using WesternAg PRS probes.
Results/Conclusions
Preliminary results suggest significant differences in abundance of decomposer fauna and in available nutrient concentration between trim and control plots, and among litterbags mesh sizes. For example nitrogen and phosphorous were significantly higher in trim plots and in large mesh litterbags. Also, decomposer arthropod abundance was higher in large mesh litterbags. There was a trend for higher arthropod abundance, higher nutrient availability and larger mass loss in large mesh litterbags, suggesting trophic dynamics mediated by decomposer microbes. These results will be further analyzed, and interpreted in the context of food web dynamics.