Abstract:The experiment was carried out in an experimental field at Ecological Experiment Station of Mire Wetland in the Sanjiang Plain, the Chinese Academy of Sciences (latitude 47°35′N; longitude 133°31′E), located in the northeast of Heilongjiang Province in China. Calamagrostis angutifolia wetland is a main wetland type in Sanjiang Plain, which accounts for 34% of the total area of wetlands. The marsh wetland (seasonal flooding) and meadow wetland (no flooding) are two typical C. angustifolia wetlands in Sanjiang Plain, which soils are predominantly humus marsh soil and meadow marsh soil, respectively. The two type wetlands of C. angustifolia are located with different water gradients, which are sensitive to the changes of water conditions. To elucidate the soil microbial activities and assess the soil quality, soil organic carbon (SOC), microbial biomass carbon (MBC), basal respiration (BR), potential respiration (PR), microbial quotient (qMB) and metabolic quotient (qCO2) in the soil profiles of marsh and meadow wetlands of C. angustifolia were investigated. The result showed that the SOC, MBC, BR, PR, and qMB decreased markedly with depth increased in 0-40cm soil profiles of marsh and meadow wetlands of C. angustifolia,while qCO2 increased obviously with depth rising. However, the SOC, MBC, BR, PR, qMB and qCO2 remained more or less unchanged in 50-100cm soil profiles for both studied soils. The soil microbial activities in soil profiles of marsh wetland were lower than those in meadow wetland, especially in 0-40cm layer of soil profiles. The content of MBC, BR, PR, and qMB in 0-10cm layer of marsh wetland were 54%, 59%, 52%, and 70% of those in meadow wetland, respectively. The notable positive correlations were found at P<0.01among MBC, BR, PR and qMB in the soil profiles of marsh wetland, and the highest correlations were between MBC with BR, PR and qMB, their coefficients were 0.999, 0.998 and 0.971, respectively. The same relationships were also found in the meadow wetland, the coefficients between MBC with BR, PR and qMB were 0.999, 0.995 and 0.930 in the soil profiles of meadow. There were negative correlations between qCO2 with MBC, BR, PR and qMB in the meadow soil profiles, and their coefficients were 0.812, 0.819, 0.829 and 0909, respectively. The same correction was found between qCO2 with MBC, BR, PR and qMB in marsh type and their coefficients were 0.685, 0.668, 0.701 and 0.803. There were prominent positive relationships at P<0.01 in the soil profiles of marsh and meadow wetland between MBC, BR, PR, and qMB with soil organic carbon, total nitrogen, total phosphorus, available nitrogen, available phosphorus and available potassium, respectively. Negative significant was found between the metabolic quotient with soil organic carbon, total nitrogen, total phosphorus and available nitrogen in both type soil profiles, whereas, there was insignificant in the relationships between the metabolic quotient with available potassium for both studies soil profiles. As the different microbial activity indicators were close correlations with each other, at the same time, the soil microbial activities were strong correlations with soil measured chemical properties. The microbial activity indicators show that the soil quality in the soil profiles of marsh of C. angustifolia wetland is better than that in meadow wetland.