Journal of Geographical Sciences ›› 2017, Vol. 27 ›› Issue (8): 999-1010.doi: 10.1007/s11442-017-1417-1

• Orginal Article • Previous Articles     Next Articles

Impact of land use conversion on soil organic carbon stocks in an agro-pastoral ecotone of
Inner Mongolia

Wei ZHAO1,2(), Zhongmin HU1, Shenggong LI1(), Qun GUO1, Hao YANG1, Tonghui ZHANG3   

  1. 1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
    3. Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, CAS, Lanzhou 730000, China
  • Received:2016-08-26 Accepted:2016-12-09 Online:2017-08-31 Published:2017-08-31
  • About author:

    Author: Zhao Wei (1982-), PhD Candidate, specialized in global carbon cycle and climate change. E-mail: zhaow.12b@igsnrr.ac.cn

    *Corresponding author: Li Shenggong, Professor, specialized in global carbon and water cycle. E-mail: lisg@igsnrr.ac.cn

  • Supported by:
    The Strategic Priority Research Program of CAS, No.XDA 05050201;The Funding for Talented Young Scientists of IGSNRR, No.2013 RC203;Youth Innovation Promotion Association of CAS, No.2015037

Abstract:

Soil organic carbon (SOC) stocks in terrestrial ecosystems vary considerably with land use types. Grassland, forest, and cropland coexist in the agro-pastoral ecotone of Inner Mongolia, China. Using SOC data compiled from literature and field investigations, this study compared SOC stocks and their vertical distributions among three types of ecosystems. The results indicate that grassland had the largest SOC stock, which was 1.5- and 1.8-folds more than stocks in forest and cropland, respectively. Relative to the stock in 0-100 cm depth, grassland held more than 40% of its SOC stock in the upper 20 cm soil layer; forest and cropland both held over 30% of their respective SOC stocks in the upper 20 cm soil layer. SOC stocks in grazed grasslands were remarkably promoted after ≥20 years of grazing exclusion. Conservational cultivation substantially increased the SOC stocks in cropland, especially in the 0-40 cm depth. Stand ages, tree species, and forest types did not have obvious impacts on forest SOC stocks in the study area likely due to the younger stand ages. Our study implies that soil carbon loss should be taken into account during the implementation of ecological projects, such as reclamation and afforestation, in the arid and semi-arid regions of China.

Key words: soil organic carbon, soil carbon profile, land use change, grazing, tillage, forest age