Response of soil microbial functional traits to annually hydrological changes in Lake Poyang wetlands

湿地自然水文节律的改变影响着湿地生态系统的稳定与安全.为探究湿地水文变化对土壤微生物活性的影响，以鄱阳湖洲滩湿地3种典型植被狗牙根（Cynodon dactylon）、南荻（Triarrhena lutarioriparia）和苔草（Carex cinerascens）下表层土壤（0~20 cm）为研究对象，对湿地土壤微生物呼吸、微生物生物量和水解酶等土壤活性特征进行连续3年的实验监测，分析年际水位变化对不同植被湿地土壤微生物活性的影响.结果表明：丰水年显著提高土壤中养分的可利用性（有机质、总磷、速效磷），提高土壤微生物生物量、微生物熵、水解酶活性，表明丰水年有利于湿地生态系统的物质循环转化.水文条件也能通过影响湿地植被生长改变土壤养分状况，进而对植被下土壤微生物活性产生显著影响.诸多土壤理化因子中，可溶性有机碳是驱动微生物活性变化最关键的因子.进一步分析表明，由植被类型所代表的长期水文累积效应对湿地土壤理化及微生物活性的调节作用大于单纯的年际水文变化.;The change of hydrological rhythm will affect the stability and security of wetland ecosystems. In order to explore the influence of annually hydrology variation on the soil microbial functional traits, we selected the surface soils (0-20 cm) under three different vegetation types-Cynodon dactylon, Triarrhena lutarioriparia and Carex cinerascens as study objects from the Lake Poyang wetlands. The soil activity characteristics of microbial respiration, microbial biomass and soil enzymes in wetland soils were tested in three consecutive years. The effects of annually water level changes on soil microbial activities in different vegetation wetlands were analyzed. The results showed that:The contents of soil available nutrient sources (including organic matter, total phosphorus, and available phosphorus) was enhanced in high flow years, as well as soil microbial biomass, microbial entropy and hydrolase activities, which were beneficial to material circulation and transformation of the wetland ecosystem. Hydrological conditions affected the state of soil nutrients by affecting the growth of wetland vegetation, and further affected the soil microbial functional traits. Among various soil physicochemical factors, dissolved organic carbon was the most critical factor driving the change of microbial functional traits. Further analysis showed that the long-term historical hydrological cumulative effects represented by different vegetations had greater impact on the soil physicochemical properties and microbial functional traits than the pure hydrological changes annually.