Arthropods and nutrient mineralization in green litter decomposition in a simulated hurricane experiment.

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Hurricanes generate disturbances in forests such as canopy opening, fallen trees and leaves which in turn alter physicochemical characteristics of the 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 habitats will result in changes in these factors. Our objective is to evaluate the effects of hurricane driven changes to forests on decomposition, decomposer communities and nutrient mineralization. Specifically, we will study the effect of a hurricane in green litter decomposition, decomposer fauna and nutrient mineralization. This study is part of the Canopy Trimming Experiment 2 performed by the Luquillo LTER at El Verde Field Station. For this, three blocks (A, B and C) were selected, each with two plots of 20m x 20m, one plot was used for control and the other Canopy opening (Trim). 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. Preliminary results suggest significant differences in abundance of decomposer fauna and in available nutrient concentration between trim and control plots, and among litterbags. 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. These results suggest that when all decomposer arthropods are present, available nutrients are higher. These results will be further analyzed, and interpreted in the context of food web dynamics.