[M-IS11] Biogeochemistry

[MIS11-06] Comparison of litter decomposition rates and dissolved organic carbon fluxes in soils across global climatic gradient

*Kazumichi Fujii¹, Chie Hayakawa², Yoshiyuki Inagaki¹, Shinya Funakawa³, Kosaki Kosaki⁴ (1.Forestry and Forest Products Research Institute, 2.Utsunomiya University, 3.Kyoto University, 4.Aichi University)

Keywords:litter decomposition, dissolved organic matter, climate change, soil

Temperature and soil moisture are crucial factors regulating microbial litter decomposition. And precipitation is a driver of leaching of dissolved organic carbon (DOC) into the mineral soil and groundwater. We compiled decomposition rates of different substrates (forest leaf litter, maize leaf litter, moss litter, lichen litter, and cellulose) and DOC fluxes in the soil profiles. Litter decomposition rates increase with increasing annual mean air temperature, but response to temperature rise differs between substrates. Cellulose and maize leaf litter display a strong dependency to temperature, while slopes of forest, lichen, and moss litter decomposition rates related to temperature rise are smaller than cellulose and maize leaf litter. Forest litter decomposition rates and manganese lignin peroxidase activities increase with increasing litter manganese concentration relative to lignin concentration. DOC fluxes from the organic horizon increase with annual precipitation or C inputs, respectively, but the proportions of DOC flux relative to C inputs are highly variable. The proportions of DOC flux relative to C inputs increase with decreasing soil pH or with increasing lignin peroxidase activities, respectively. The responses of litter decomposition rates and leaching of dissolved organic matter to climate are affected by litter recalcitrance and soil properties as well.