Factors Affecting Decomposition Rates in Temperate vs. Tropical Leaves

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Headwater streams in forested catchments mainly rely on allocthonous inputs as their primary energetic resource. Factors influencing leaf breakdown rates in forested headwaters have been thoroughly studied in tropical and temperate regions. Studies suggest that breakdown rates in tropical streams are faster compared to their temperate counterparts, which could be explained by resource quality and differences in colonizing communities. We examined leaf decomposition with and without a common temperate-zone shredder (Tallaperla maria) in a laboratory setting. Stonefly nymphs were raised on individual leaf-type diets using two temperate (Acer rubrum andQuercus prinus) and two tropical (Dacryodes excelsa and Cecropia schreberiana) leaf species. Percent leaf mass loss was determined after four intervals over a 56-d period and decomposition was estimated using an exponential decay model. In addition, to assess consumer responses to differences in resource, we quantified instantaneous growth rates for stoneflies. Decay rates (k) ranged from -0.0168 to -0.1224 with maple decomposing the fastest for both consumer treatments. As predicted, leaf decomposition rates were consistently faster for consumer treatments (with stonefly shredders).


Society for Freshwater Science Annual Meeting (SFS)


Louisville, KY