Decomposition in tropical forests: a pan-tropical study\ud of the effects of litter type, litter placement and\ud mesofaunal exclusion across a precipitation gradient

摘要

Decomposition of dead plant material is an important process by which carbon fixed during photosynthesis is returned to the atmosphere (Schlesinger 1977; Singh & Gupta 1977), and is critical for nutrient cycling (Swift et al. 1979, Sayer 2006). As a primarily biotic process, decomposition and concomitant CO2 release and nutrient mineralization depend upon a number of drivers that directly and indirectly affect decomposer activity.\udEmpirical studies, conducted largely in the temperate zone, have identified three key drivers of decomposition, in order of decreasing importance: climate, litter quality (e.g. chemical composition) and the decomposer community (e.g. bacteria, fungi and soil fauna (Meentemeyer 1978, 1984; Coûteaux et al. 1995). Despite the established importance of the decomposer community (Seastedt 1984; Bradford et al. 2002a), it is typically\udassumed that decomposition can be modelled using climate\udand litter chemistry data alone, with either no or very minimal information on the decomposer community (e.g. microbial biomass data; but see Moorhead & Sinsabaugh 2006; Wall et al. 2008). Models also typically assume that above- and below-ground decomposition are controlled by the same factors (Moorhead et al. 1999). Several lines of evidence suggest that these assumptions may not always hold, especially in tropical ecosystems