Linking soil nutrient cycling and microbial community with vegetation cover in riparian zone

Abstract

The riparian zone is a spatially fluctuating ecotone between terrestrial and aquatic ecosystems and has key ecological functions, due to specific geographic conditions and seasonal environmental changes. The comprehensive functions of vegetation cover and microbial community in riparian zones might generate positive consequences for nutrient cycling. In this study, four different vegetation-covered soils in a riparian zone on the Yangtze River was selected. Soil nutrient concentration and microbial properties, including nitrogen (N) and phosphorus (P) cycling and microbial community structure, were analyzed, and the relationships among soil nutrient concentrations, microbial properties and vegetation covers were also linked. Vegetation covers increased soil NH4+-N supply by enhancing N mineralization and positively affected available N retention through inhibition of soil nitrification. Plant species outweighed plant biomass in determining soil microbial properties related to P mineralization, including phosphatase activities and functional gene abundances. Vegetation covers significantly increased Acidobacteria and Mortierellomycota relative abundances. Soil bacterial and fungal communities had opposing responses to the impacts of plant species richness and biomass. In the riparian zone, plant species outweighed plant biomass in promoting soil N and P mineralization, and vegetation covers, regardless of plant species, improved available nutrient supplies and retentions and shaped soil microbial community.