Shared responsibility of earthworms and microbes in leaf litter decomposition in temperate forest soil

초록

Earthworms substantially influence soil C and N cycling, yet their net effects on litter decomposition and nutrient redistribution remain uncertain, particularly for epi-endogeic Amynthas spp., which dominate many temperate forests. Further, their interactions with microbial communities during early stage litter decay remain poorly understood. Therefore, we aimed to investigate how Amynthas spp. affect litter-derived C and N mineralization, their vertical redistribution in soil, and microbial biomass and enzymatic C-N acquisition strategies. An 80-day microcosm experiment was conducted using two treatments: soil + litter (SL*) and soil + litter + earthworms (SL*E). Dual-labeled (13C, 15N) Quercus serrata leaf litter enabled tracing of litter-derived C and N in CO2 efflux, soil layers, and earthworm biomass. Microbial biomass and extracellular enzyme activities were quantified to assess functional responses. Earthworms increased cumulative soil CO2 efflux 2.5-fold, increased litter-derived C and N incorporation into the 0-10 cm layer by 27% and 48%, respectively, while contributing little to deeper translocation. They enhanced N mobilization, as evidenced by elevated inorganic and dissolved organic N. Microbial enzyme activities shifted toward cellulose- and chitin-degrading pathways (higher cellobiohydrolase and beta-N-acetylglucosaminidase, lower leucine aminopeptidase), whereas microbial C/N acquisition remained stoichiometrically balanced. Overall, our findings highlight that Amynthas spp. accelerate early stage litter decomposition, enhance nutrient mobilization, and restructure microbial enzymatic strategies in temperate forest soils.

키워드