Nitrogen addition and plant functional type mediate the mesofauna-driven litter element release of subtropical forest

PurposeSoil mesofauna-associated biogeochemical cycles could be mediated by nitrogen (N) deposition and plant functional types. However, N addition effects on the contribution of soil mesofauna to litter element release under different plant functional types remain unclear.MethodsA litterbag experiment with two mesh sizes (2 and 0.1 mm) examined the soil mesofauna's effect on litter carbon (C), N, and phosphorus (P) release of three functional types (evergreen broadleaf, deciduous broadleaf, and coniferous: 6 tree species for each group). Litterbags were exposed to varying N deposition levels (0, 20, and 40 kg N ha-1 yr-1) in a subtropical forest in southwest China.ResultsN addition and soil mesofauna promoted litter C, N, and P loss across three plant functional types. The soil mesofauna's effects on litter N loss were lower in deciduous broadleaf than in evergreen broadleaf and coniferous litter. However, the soil mesofauna's effects on litter P loss were greater in evergreen broadleaf than in deciduous broadleaf and coniferous litter. Further, N addition stimulated the soil mesofauna's effects on litter N release only in evergreen broadleaf. Soil mesofauna's contribution to C and P loss correlated with the initial litter C/P ratio across 18 species. N addition effects were greater under low-N than high-N treatments in 0.1 mm litter bags.ConclusionThe findings suggested N addition and plant functional types independently mediated mesofauna-driven litter element release, highlighting the importance of soil mesofauna and plant functional types for belowground biogeochemical cycles via litter pathways in subtropical regions experiencing pronounced N deposition.