Salinization aggravates microbial nutrient limitation and decreases microbial carbon use efficiency in tidal wetland soils

Soil (salinity; pH; DOC, dissolved organic C; NH4+, ammonia; PO43−, phosphate; SOC, soil organic carbon; TN, total nitrogen; TP, total phosphorus; soil C:N, SOC:TN; soil C:P, SOC:TP; soil N:P, TN:TP), plant (aboveground biomass; belowground biomass; root C; root N; root P; root C:N; root C:P; root N:P), microbe (microbial biomass C; microbial biomass N; microbial biomass P; microbial biomass C:N; microbial biomass C:P; microbial biomass N:P; CUE, carbon use efficiency) and enzyme activity (BG, β-1,4-glucosidase; NAG, β-1,4-N-acetylglucosaminidase; AP, acid phosphatase; enzyme C:N, BG:NAG; enzyme C:P, BG:AP; enzyme N:P, NAG:AP) along the salinity gradient (Low: Low-salinity site; Mid: Middle-salinity site; High: High-salinity site) between seasons (growing season: green sheet; non-growing season: orange sheet). All stoichiometries (C:N, C:P, and N:P) of soils, roots, microbial biomass, and enzymes in the present study were expressed as molar ratios.