The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests

We present the results from a litter translocation experiment along a 2800-m elevation gradient in Peruvian tropical forests. The understanding of the environmental factors controlling litter decomposition is important in the description of the carbon and nutrient cycles of tropical ecosystems, and in predicting their response to long-term increases in temperature. Samples of litter from 15 species were transplanted across all five sites in the study, and decomposition was tracked over 448 d. Species' type had a large influence on the decomposition rate (k), most probably through its influence on leaf quality and morphology. When samples were pooled across species and elevations, soil temperature explained 95% of the variation in the decomposition rate, but no direct relationship was observed with either soil moisture or rainfall. The sensitivity of the decay rate to temperature (kappa(T)) varied seven-fold across species, between 0.024 and 0.169 degrees C-1, with a mean value of 0.118 +/- 0.009 degrees C-1 (SE). This is equivalent to a temperature sensitivity parameter (Q(10)) for litter decay of 3.06 +/- 0.28, higher than that frequently assumed for heterotrophic processes. Our results suggest that the warming of approx. 0.9 degrees C experienced in the region in recent decades may have increased decomposition and nutrient mineralization rates by c. 10%.