Wetlands store one third of global soil organic carbon(SOC)and are strongly affected by artificial drainage.The impact of drainage-induced water-table decline on carbon cycling in different wetlands,particularly microbial transformation processes,remains unclear.To address this knowledge gap,we collected soil samples from two typical wetlands of China(a nutrient-poor bog located in Dajiuhu and a nutrient-rich fen in Hongyuan)and conducted an incubation experiment with the addition of 13C-labeled glucose to analyze the effects of short-and long-term drainage on SOC decomposition,extracellular enzyme activity,microbial carbon use efficiency(CUE),and microbial carbon accumulation efficiency(CAE).The results showed that both short-and long-term drainage significantly increased SOC decomposition rates in both wetlands(from 1.47 pg C·g-1·h-1 in submerged soils to 2.47 μg C·g-1·h-1 in drained soils),microbial biomass carbon derived from glucose(from 0.21 mg C·g-1 to 1.00 mg C·g-1)and CAE(from 0.29 to 0.73),but did not alter CUE(ranging from 0.34 to 0.86).Long-term drainage increased α-glucosidase activity in the Dajiuhu wetland and decreased β-glucosidase and phenol oxidase activities in the Hongyuan wetland.In conclusion,drainage enhanced the'microbial carbon pump'and its effi-ciency in wetlands mainly via increasing microbial intracellular metabolism(including respiration),but also acce-lerated SOC decomposition.
microbial carbon use efficiencymicrobial carbon accumulation efficiencysoil organic carbon cyc-lingwetlanddrainage
维普
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