Interaction Between Decomposing Litter And Soil Fauna Of The Betula Ermanii Forest Floor Of The Changbai Mountains, China

Litter decomposition is one of the most important pathways in energy transformation andmaterial cycles of the terrestrial ecosystem, especially for alpine forest ecosystems. Soil faunaplay a key role in the process of litter decomposition as they breakdown, consume, and digestlitter, as well as stimulate microbial activities. We conducted a24month experiment of litterdecomposition on Betula ermanii forest floor of the Changbai Mountains, China, using threemesh sized bags (4mm,2mm and0.01mm) with6litter treatments. There were threetreatments of single species litterbags of B. ermanii (BE), Rhododendron aureum (RA) andParasenecio komarovianus (PK). The other three treatments were an equal amount mixture ofthe three species: BE+RA, BE+PK, and BE+RA+PK.ANOVA, principal components analysis(PCA) and canonical correspondence analysis (CCA) were used to determine differences inlitter mass loss and nutrient release between the treatment means. We explored interactionbetween decomposing litter and soil fauna of B. ermanii forest floor of the ChangbaiMountains, China. The main results were summarized as follows:（1）R. aureum has the lowest mass loss while P. komarovianus has the highest mass lossover the24months of incubation time. After24months of the experiment, mass loss of P.komarovianus in4mm,2mm and0.01mm mesh size were77.13%,80.73%and67.44%,respectively. While mass loss of R. aureum in4mm,2mm and0.01mm mesh size were41.44%,40.40%and38.36%, respectively. Mass loss were higher at the first12months thanthat between12and24months. Mass loss of BE+RA and BE+RA+PK were higher than thatR. aureum. Mass loss of BE+PK and BE+RA+PK were lower than that R. aureum.（2）During the experiment, overall, C release was found in all litter treatments. Naccumulation was found with all litter treatments at the6and8th month of the experiment. Paccumulation (immobilization) was found with all litter treatments at the20and22th monthof the experiment. Ca changes were different in all litter treatments. Mg accumulation(immobilization) was found in B. ermanii in4mm and2mm mesh size at the6th month ofthe experiment and R. aureum in2mm and0.01mm mesh size at the12th month of theexperiment. Mn accumulation (immobilization) was found in P. komarovianus in4mm and2mm mesh size at the18th month of the experiment. During the experiment, mixed-specieslitter treatments can limited or promoted litter nutrient release than single-species littertreatments depend on litter heterogeneity and mesh size.（3）Thirty five groups of soil fauna were obtained in litterbags during the the24monthsof incubation time. The most dominant groups were Isotomidae, Oribatida and Enchytraeidae.Common groups were Pseudachorutidae, Mesostigmata, Sminthuridae, Diptera larva, Neanuridae, Prostigmata, Tomoceridae, Hypogastruridae and Juliformia. Abundance andShannon-Wiener index of soil fauna in BE+RA and BE+RA+PK were higher than that B.ermanii and R. aureum at the8th month of the experiment. Abundance and Richness of soilfauna in BE+PK and BE+RA+PK were higher than that B. ermanii and P. komarovianus. Thepromoting effect of litter mixing on the soil faunal community composition is only short termand is dependent on substrate quality.（4）In our study, the impact of soil fauna on mass loss of both mixed and single specieslitterbags changed from limited to significantly positive as the mass loss advances. After12months of the experiment, faunal effect on mass loss of R. aureum was29.09%. Faunal effecton C, N, P, Ca, Mg and Mn remaining were limited and positive. Stepwise multiple regressionshowed that abundance of soil fauna was affected by Mn remaining, richness of soil faunawas affected by C, Mg and Mn remaining, Shannon-Wiener index of soil fauna was affectedby litter mass loss, Mg and Ca remaining. Canonical correspondence analysis (CCA) revealedrelationships between soil faunal community and nutrient remaining. Soil faunal communityof R. aureum was affected by C remaining in4mm mesh size between18and24months ofthe experiment. Soil faunal community of R. aureum was affected by C/N ratio in2mm meshsize at8,10,18,22and24th month of the experiment. Interaction between decomposing litterand soil fauna is closely related to soil faunal food web, litter mixture composition and litterquality.