Microbiota, fauna, and mesh size interactions in litter decomposition

Abstract

Plant litter decomposition is a key process in carbon and nutrient cycling. The critical role of soil‐faunal community composition in decomposition has been demonstrated using different mesh size litterbags to control exposure of litter to different faunal size classes. However, the faunal community surrounding the litterbags has not been manipulated despite potentially large indirect effects of their activity on biotic and abiotic processes that control litter decomposition at the habitat‐scale. We combined microcosm and litterbag techniques to facilitate a more comprehensive understanding of the role of direct and indirect effects of soil‐faunal community composition on litter decomposition. We placed litterbags of three mesh sizes across model grassland miniecosystems manipulated to enable communities containing 1) microfauna; 2) micro‐ and meso‐fauna; 3) micro‐, meso‐ and macro‐fauna. All communities contained bacteria and fungi. The approach permitted correction of mesh size artefacts inherent to field studies. Indirect effects have been divided into two separate terms, direct‐indirect effects and indirect effects. Decomposition in micromesh litterbags was significantly decreased by the indirect effects of meso‐ and macro‐fauna. In macrofauna communities, increased mesh size significantly increased decomposition through mesh size per se and faunal effects. Relative effects of manipulated faunal community composition on litter mass loss and C:N ratio were equivalent for green and senesced litter. The presence of meso‐ and macro‐fauna increased litter decomposition rate overall despite inhibiting decomposition by microfauna, bacteria and fungi through indirect effects.

Plant Litter Decomposition and Nutrient Release in Peatlands

“…The litter bag technique consists in confining fresh litter in mesh bags that are placed on the ground and periodically collected so as to measure the remaining litter mass and associated litter chemistry [Singh and Gupta, 1977]. This simple and cheap technique has been, however, criticized because (1) confined litter bags may create their own microenvironment different from surrounding bulk soil; (2) litter bags may exclude specific faunal groups in relation to the mesh size [Nieminen and Setala, 1997;Bradford et al, 2002]; and (3) litter bags are usually filled with litter from a single species [Gartner and Cardon, 2004]. Nevertheless, the litter bag technique is widely applied to monitor temporal mass loss in both terrestrial and aquatic environments.…”

Influence of habitat, litter type, and soil invertebrates on leaf-litter decomposition in a fragmented Amazonian landscape

“…This mesh size prevents the colonization of the litter by macroinvertebrates (ants, beetles, Diplopoda, etc. ), although some elements of the soil mesofauna, such as larger-bodied Acari and Collembola, may be excluded as well (Bradford et al 2002). Three 1-cm 2 perforations were made on each side of the control bags to facilitate the access of these invertebrates.…”

“…The rate at which litter is decomposed is in large part influenced by its chemical composition, by the activity and composition of soil organisms, and by the physical micro-environment (Meentemeyer 1978;Seastedt et al 1983;Finzi et al 2001;Gonza´lez and Seastedt 2001;Bradford et al 2002). All of these three factors are known or presumed to be altered in fragmented forests and in areas of secondary growth.…”

“…The drier microclimatic conditions along forest edges and in early successional forests can, potentially, inhibit the activity of soil macroinvertebrates. These organisms play a vital role in leaf-litter decomposition, by consuming litter and, by physically breaking up organic material, facilitating the activity of microbes (Petersen and Luxton 1982;Bradford et al 2002). Variations in the abundance, species richness, and composition of many groups of soil invertebrates are known to occur in response to edge effects or changes in vegetation cover (Lasebikan 1976;Belshaw and Bolton 1993;Eggleton et al 1995;Didham 1997;Carvalho and Vasconcelos 1999;Vasconcelos 1999).…”

Produção de serrapilheira e decomposição foliar em fragmentos florestais de diferentes fases sucessionais no Planalto Atlântico do estado de São Paulo, Brasil

“…Thus, litter production is expected to increase with forest development (Vidal et al 2007). The amount of litter input, in turn, influences the composition of the decomposer community and associated with the drier microclimate conditions, typical of early successional forest fragments, can reduce the activity of decomposers (Bradford et al 2002), resulting in a less efficient nutrient cycling.…”