【摘要】 研究对比了淹水和盐度升高对长江口滨海湿地本土植物芦苇(Phragmites australis)和入侵植物互花米草(Spartina alterniflora)土壤微生物生物量(生物量碳-MBC、生物量氮-MBN)及其占土壤有机碳(SOC)和总氮(TN)比例的影响。淹水条件下芦苇土壤MBC、MBN、MBC/SOC和MBN/TN显著降低(分别为26.0、46.7、16.5和42.2%)。而淹水条件下互花米草土壤微生物生物量指标变化均不显著。随盐度升高,芦苇土壤除MBC/SOC外,MBC、MBN和MBN/TN均显著降低(分别为26.4、36.2和30.2%),而互花米草土壤微生物生物量指标降低程度相对较低。淹水+盐度处理加剧了盐度对两种植物土壤微生物生物量指标的影响。然而,互花米草土壤微生物与土壤营养因子对水、盐变化的敏感性较低。因此,在未来海平面上升条件下,入侵种互花米草与本土种芦苇相比土壤微生物群落更能适应淹水延长和盐水入侵等环境变化,而且互花米草入侵可能将进一步加剧。更多还原

【Abstract】 In the soils of native Phragmites australis and exotic Spartina alterniflora(sampled from the coastal wetland in the Yangtze Estuary), the changes in microbial biomass carbon(MBC), microbial biomass nitrogen(MBN), MBC/MBN ratio and their proportion in soil organic carbon(SOC) and total nitrogen(TN) were investigated under waterlogging and increased salinity treatments. The results showed that the MBC, MBN, MBC/SOC, MBN/TN in P. australis soils under waterlogging treatment decreased significantly, by on average 26.0, 46.7, 16.5 and 42.2%, respectively, compared to non-waterlogging treatment. However, in S. alterniflora soil, the indices of soil microbial biomass(expect for MBN/TN) did not exhibit notable changes under waterlogging treatment. With increasing salinity, MBC, MBN and MBN/TN significantly decreased in P. australis, by on average 26.4, 36.2 and 30.2%, respectively. Relative to P. australis, the decrease degree of the soil microbial indices mentioned above in S. alterniflora soil was lower. There was no significant effect of salinity on MBC/MBN in soils of both two species. Under the combined waterlogging and increased salinity, the valley-values of MBC, MBN, MBC/SOC, and MBN/TN occurred, and the peak-values of MBC/MBN occurred in both P. australis and S.alterniflora soils. Relative to P. australis soil, the sensitivity of soil microbial biomass and nutrients in S. alterniflora soil to waterlogging and increased salinity was lower. The probable reason was that the growth(root biomass) of S. alterniflora showed a high tolerance to flooding and salinity stress, and the soil nutrient kept a relatively stable level. Compared to the native P. australis, the invaded S. alterniflora in the coastal wetlands may stabilize the associated soil microbial characteristics under conditions of rising sea level and simultaneous saltwater intrusion, and the invasion of S. alterniflora may be exacerbated.更多还原