Characterization of degradation of wetland plant communities on floodplain in typical steppe region of Inner Mongolia Plateau, China

Abstract

Aims River floodplain meadow is biologically highly productive, but excessive grazing has degraded most of it. Our objective was to analyze changes of vegetation in a Xilin River Basin (Inner Mongolia) wetland meadow to provide information for the restoration and management of degraded wetland. Methods We compared fenced (non-grazed) and grazed sites within the wetland for vegetation and soil charac-teristics: plant community composition, aboveground biomass, plant height, internode length, leaf length and width of major species, plant community root biomass and distribution, soil moisture, soil bulk density, soil microbial biomass and soil carbon and nitrogen content. Important findings Grazing affects plant dominant species, gradually replacing original wetland plants with more drought-resistant ones. It also significantly reduces the aboveground and belowground biomass. Plants in degraded wetland meadow are smaller, thus resulting in the decline in community productivity; Grazing also causes a decrease in soil moisture. In the low flood plain, soil moisture and root biomass both increase with increasing soil depth; however, in the high flood plain, soil moisture does not change with soil depth and is similar to that of the typical steppe. Soil bulk density increases as soil is compacted by animal grazing and trampling. In high and low floodplain wetlands, the changes of soil microbial biomass carbon and nitrogen between ungrazed and grazed sites are varied. In low floodplain wetlands, grazed areas have increased microbial biomass, while in high floodplain wetlands, grazed areas have significant less microbial biomass, carbon and ni-trogen.