Simulated hurricane treatment reduces basidiomycete litter mat cover in subtropical wet forest

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The main effect of hurricanes, the transfer of leaves and branches from the canopy to the forest floor, was simulated by canopy trimming in 30 x 30 m plots in subtropical wet forest of Puerto Rico.  Comparisons were made between hurricane and control plots within each of three replicate blocks. Treatments were applied in a randomized complete block design. The extent of litter matted together by basidiomycete fungi (agaric mushrooms that produce white-rot by degrading lignin) was assessed along four 5-m transect lines within each of three 5 x 5 m subplots per plot before and after the trimming treatment.  Mean percent leaf mat cover was calculated per plot and treatments were compared within blocks using 2-sample 2-tailed t-tests. Leaf litter mat cover did not differ between the hurricane treatment and control plots before the trimming and debris addition. All three blocks showed a significant (P < 0.0001) difference between the hurricane treatment and control plot in March and May, 3-5 months after trimming. Percent cover by basidiomycete-bound litter mats was 25-43% in the control plots and 2-8% in the hurricane treatment plots after trimming. Leaf litterfall rates and leaf litter moisture were both lower in trimmed than in control plots, and contributed to the decline in agaric fungi. Loss of litter mat cover and changes in decomposer functional group dominance from basidiomycete fungi that degrade lignin (white-rot) to microfungi that cause other types of rot is expected to alter decay products and hence soil microbial communities and their enzymes and possibly soil carbon fractions in the simulated hurricane plots relative to the control plots.