凋落物输入变化对森林土壤CH4吸收的影响OA北大核心CSTPCD

Methane(CH4)is the second important anthropogenic greenhouse gas after carbon dioxide(CO2).For-est soils are a sink for atmospheric CH4 and play an important role in modulating global CH4 budget.Litter is impor-tant carbon and nutrient sources for forest soils.Litter decomposition could increase soil carbon and nutrient concen-trations and reduce oxygen concentration beneath the soil surface as well as the oxidation and diffusion of soil CH4.However,it remains unclear whether litter input changes CH4 uptake in forest soils.In this study,a microcosm experiment was conducted in a subtropical forest,and soil CH4 flux under the conditions with and without litter input was monitored monthly by chambers in a Chinese fir(Cunninghamia lanceolata)plantation over one year.We found that litter removal significantly increased soil CH4 uptake in Chinese fir plantation.We further analyzed the changes in soil CH4 flux after litter removal(leaf and root)and double litter input at six forest sites in other cli-matic zones.We found that litter removal significantly increased soil CH4 uptake in broadleaved forests by 16.5％.On the contrary,double litter input decreased soil CH4 uptake by 11.1％and 20.0％in broadleaved and coniferous forests,respectively,suggesting that the function of CH4 sink in forest soils decreased with additional litter input.Our results suggest that litter input is an important factor affecting CH4 flux uptake in forest soils,and that litter layers may reduce atmospheric CH4 uptake by forest soils through reducing the oxygen concentration beneath soil surface.