The response of microbial composition and enzyme activities to hydrological gradients in a riparian wetland

Abstract

Hydrological condition is one of the important factors impacting microbial structure in riparian wetlands. However, how these microbial communities respond to different hydrological gradients through environmental factors remains uncertain. The main objective of this research was to identify soil microbial community structure under various water levels in a wetland and provide instructive information for assessing wetland function. Soil samples were collected from sampling plots under different hydrological conditions. Soil parameters, including total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), soil organic carbon (SOC), and dissolved organic carbon (DOC), were utilized to identify the effect of different hydrological conditions on soil properties. The quantity and abundance of phospholipid fatty acid (PLFA) and enzyme activities (alkaline phosphatase, urease, and invertase) were utilized to evaluate variation of microbial community. The PLFA of bacteria, fungi, and actinomycetes accounted for 80.64–85.09%, 9.09–12.23%, and 5.06–6.02% of the total PLFA in wetland soil, respectively. Soil water content showed significant correlation with microbial PLFA and enzyme activities. Long-term inundation led to substantial alteration in the microbial biomass and structure. The redundancy analysis (RDA) identified that AN and AP were the critical factors impacting the structure of microbial community, and AP and SOC were principal factors to soil enzyme activities. Soil water content was the principal controlling factor in the formation of special environment for microbial community. The perennial flooded condition stimulated the increase of bacteria, fungi, and actinomycetes through changing AN and AP levels. Thus, the relation between microbial community and hydrological gradients was significantly impacted by soil nutrition.