Controls over leaf litter decomposition in wet tropical forests.
Tropical forests play a substantial role in the global carbon (C) cycle and are projected to experience significant changes in climate, highlighting the importance of understanding the factors that control organic matter decomposition in this biome. In the tropics, high temperature and rainfall lead to some of the highest rates of litter decomposition on earth, and given the near-optimal abiotic conditions, litter quality likely exerts disproportionate control over litter decomposition. Yet interactions between litter quality and abiotic variables, most notably precipitation, remain poorly resolved, especially for the wetter end of the tropical forest biome. We assessed the importance of variation in litter chemistry and precipitation in a lowland tropical rain forest in southwest Costa Rica that receives >5000 mm of precipitation per year, using litter from 11 different canopy tree species in conjunction with a throughfall manipulation experiment. In general, despite the exceptionally high rainfall in this forest, simulated throughfall reductions consistently suppressed rates of litter decomposition. Overall, variation between species was greater than that induced by manipulating throughfall and was best explained by initial litter solubility and lignin:P ratios. Collectively, these results support a model of litter decomposition in which mass loss rates are positively correlated with rainfall up to very high rates of mean annual precipitation and highlight the importance of phosphorus availability in controlling microbial processes in many lowland tropical forests.
Wieder
William R
WR
Institute for Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, Colorado 80309, USA. will.wieder@colorado.edu
Cleveland
Cory C
CC
Townsend
Alan R
AR
D001673:Biodegradation, Environmental; D003364:Costa Rica; D009584:Nitrogen / Q000378:metabolism; D009930:Organic Chemicals / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D011891:Rain; D012987:Soil; D012995:Solubility; D014197:Trees / Q000378:metabolism; D014329:Tropical Climate
D009930:Organic Chemicals; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen