Impact of changes in rainfall amounts predicted by climate-change models on decomposition in a deciduous forest

Climate-change models predict a more intense hydrological cycle, with both increased and decreased amounts of rainfall in areas covered with temperate deciduous forests. These changes could alter rates of litter decomposition, with consequences for rates of nutrient cycling in the forest ecosystem. To examine impacts of predicted changes in precipitation on the rate of decay of canopy leaves, we placed litterbags in replicated, fenced 14 m² low-rainfall and high-rainfall plots located under individual rainout shelters. Unfenced, open plots served as an ambient treatment. Litter in the high-rainfall and ambient plots decayed 50% and 78% faster, respectively, than litter in the low-rainfall plots. Litter in the ambient plots disappeared 20% faster than in the high-rainfall treatment, perhaps via greater leaching during heavy rainfall events. Ambient rainfall during the experiment was similar in total amount to the high-rainfall treatment, but was more variable in intensity and timing. We used litterbags of different mesh sizes to examine whether changes in rainfall might alter the impacts of major categories of the fauna on litter decay. However, we found no consistent evidence that excluding arthropods of different sizes affected litter decay rate within any of the three rainfall treatments. This research reveals that changes in rainfall predicted to occur with global climate change will likely strongly alter rates of litter decay in deciduous forests.