Effects of land use on soil water soluble organic C and microbial biomass C concentrations in the Sanjiang Plain in northeast China

摘要

Four land-use types were selected: Deyeuxia angustifolia wetland, upland forest, two farmlands (cultivated 1 and 9 years, respectively) of soils previously under Deyeuxia angustifolia wetland, and abandoned cultivated soil; and soil organic C, water soluble organic C, microbial biomass C, and hot-water extractable C were measured, to estimate the influence of changing land use and cultivation on organic C fractions, and the distribution of labile fraction organic C through soil profiles in the Sanjiang Plain of northeast China. Results indicated that long-term cultivation caused a significant decline in all examined parameters, while abandonment of cultivated wetlands resulted in an increase in examined parameters. The intact Deyeuxia angustifolia wetland soil had much higher labile fraction organic C concentrations in the topsoil when compared to upland forest, abandoned cultivated and cultivated soils. However, there were no significant subsoil differences at all sites, suggesting the effects of land use on labile fraction organic C occurred mainly in the topsoil (0-20 cm).