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Effects of land-use change on soil organic carbon and nitrogen in density fractions and soil δ13C and δ 15N in semiarid grasslands
- Qiu, Liping, Wei, Xiaorong, Ma, Tiane, Wei, Yanchun, Horton, Robert, Zhang, Xingchang, Cheng, Jimin
- Plant and soil 2015 v.390 no.1-2 pp. 419-430
- afforestation, cropland, grasslands, land use change, nitrogen, nitrogen content, semiarid zones, shrublands, soil density, soil organic carbon, soil texture, China
- AIMS: The objectives of this study were to determine the response of soil organic carbon (SOC) and nitrogen (N) in different density fractions and the response of δ¹³C and δ¹⁵N signatures of soil to land-use change in a semiarid grassland. METHODS: We measured soil δ¹³C and δ¹⁵N and the concentrations of SOC and N in whole soil and in the light and heavy fractions in adjacent tracts of native grassland, cropland, and shrubland in a semiarid region of China. The cropland and shrubland were established on existing grassland 27 years ago. RESULTS: The conversion of grassland to cropland or to shrubland significantly decreased SOC and N concentrations and stocks in both whole soil and density fractions in the 0–80 cm soil layer. The decreases in SOC and N stocks associated with the heavy fraction accounted for >90 % of the total decrease in the 0–80 cm soil layer after grassland cultivation or afforestation. The conversion of grassland to cropland or to shrubland significantly enriched soil δ¹³C but depleted δ¹⁵N. CONCLUSIONS: Our results suggested that the losses of SOC and N in whole soil after land-use changes in this semiarid grassland were primarily due to losses of SOC and N associated with the heavy fraction.