三江平原4种典型湿地土壤碳氮分布差异和微生物特征

选择三江平原洪河湿地保护区4种典型湿地类型：小叶章+沼柳湿地、小叶章湿地、毛苔草湿地和芦苇湿地作为研究对象，分析了不同湿地土壤有机碳(SOC)、全氮(TN)含量和微生物活性指标(土壤蔗糖酶、纤维素酶、过氧化氢酶、微生物生物量碳MBC、微生物生物量氮MBN、微生物呼吸速率MBR、微生物商q_MB和代谢商q CO₂)的变化及其相互关系.结果表明： SOC和TN含量均随土层深度增加而减少，不同湿地类型之间具有极显著性差异(P<0.01).各湿地土壤酶活性(除过氧化氢酶)、MBC、MBN含量和MBR均以表层(0～10 cm)最高，并随着土层深度的增加而降低.在0～30 cm土层内，小叶章+沼柳湿地和小叶章湿地SOC、TN含量、土壤酶活性、MBC、MBN含量、MBR、q_MB和qCO₂均高于淹水区的毛苔草湿地和芦苇湿地.统计分析表明，SOC、TN与微生物活性指标(qCO₂除外)均存在极显著正相关关系(P<0.01).表明研究区土壤微生物特征对SOC、TN的变化具有重要的影响和指示作用.

Carbon and nitrogen distributions and microbial characteristics in the soils of four types of wetlands in Sanjiang Plain,Northeast China.

Four typical wetlands in the Honghe Wetland Reserve of Sanjiang Plain (i.e. wetlands with the following dominant plant species: Calamagrostis angustifolia+Salix brachypoda, Calamagrostis angustifolia, Carex lasiocarpa, and Phragmites australis) were selected to analyze the changes of soil organic carbon (SOC) and total nitrogen (TN) contents and various indices of microbial characteristics including soil sucrose, catalase, cellulase, microbial biomass carbon/nitrogen (MBC/MBN), microbial respiration (MBR), microbial quotient (q_MB), and metabolic quotient (qCO₂), as well as the correlations among them. The results showed that SOC and TN contents decreased with increasing the soil depth, and varied significantly (P<0.01) in the different wetland types. Soil enzyme activities (except catalase), MBC, MBN and MBR also decreased significantly with increasing the soil depth in the wetlands with the greatest activities being detected in surface soil (0-10 cm). In soil layer of 0-30 cm, several parameters (including SOC, TN, soil enzyme activities, MBC, MBN, MBR, q_MB and qCO₂) were higher in the wetlands dominated by C. angustifolia+S. brachypoda and C. angustifolia, compared with those with C. lasiocarpa and P. australis as dominant plant species. Statistical analyses revealed significant correlations (P<0.01) between major microbial indicators (except qCO₂) with SOC and TN contents in the soils. It demonstrated that the microbial characteristics were the major indicators, and played an important role in the changes of SOC and TN in wetland soils.