Applicability of the microbial inoculation method in the study on litter decomposition

The decomposition of litter is one of the core links of the material cycling of ecosystem, studying this process is helpful for understanding the indirect effects of environmental alterations on the stability of ecosystems. In the traditional method litter is placed into litterbags which are placed outdoor on or in soil. Since under these conditions it is very difficult to analyze the parameters involved in litter decomposition separately, these experiments are also done indoor under controlled conditions. Inoculating the litter with soil or phyllo sphere microorganisms and preventing any other interaction of the litter samples with the surrounding soil is an emerging method in the indoor investigation of plant litter decomposition, in order to experimentally minimize the impacts of invading soil constituents on litter decomposition parameters. However, few parallel-experiments were conducted to compare this inoculation method with the traditional litterbag method. Hence, it is unclear whether the inoculation method, when compared to the litterbag method, would cause artifacts with respect to the decomposition rate and microbial communities under controlled indoor conditions. In the present study, litters of Pinus tabuliformis, Salix babylonica and mixed litter from a Robinia pseudoacacia forest, representing litters with different decomposabilities, were chosen for a comparative experiment. Each type of litter was incubated under controlled indoor conditions for six months using the litterbag method and soil microorganism inoculation method. The decomposition rates and the litter fungal communities of the same litters were compared. Using microbial inoculation method, the decomposition rates exhibited no significant differences relative to those observed in the litterbag method. More importantly, the disturbance by biotic and abiotic factors from external soil on the fungal community in the samples could be excluded.