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Journal of Desert Research ›› 2022, Vol. 42 ›› Issue (5): 36-43.DOI: 10.7522/j.issn.1000-694X.2022.00010

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Soil particle organic carbon isotope decomposition characteristics of ecological restoration grassland and woodland in alpine region

Guangzhao Han1,2,3(), Guangchao Cao1,2,4(), Shengkui Cao1,2,3, Wenqian Ye1,2,3   

  1. 1.Key Laboratory of Ministry of Education of Earth Surface Process and Ecosystem Conservation in Qinghai-Tibet Plateau /, Qinghai Normal University,Xining 810008,China
    2.Qinghai Provincial Key Laboratory of Physical Geography and Environment Process /, Qinghai Normal University,Xining 810008,China
    3.School of Geographical Sciences, Qinghai Normal University,Xining 810008,China
    4.Academy of Plateau Science and Sustainability (APSS),People's Government of Qinghai Province & Beijing Normal University,Xining 810008,China
  • Received:2022-01-04 Revised:2022-02-03 Online:2022-09-20 Published:2022-09-22
  • Contact: Guangchao Cao

Abstract:

In order to investigate the decomposition characteristics of soil particulate organic carbon in alpine ecological restoration land, the restoration grassland and woodland on the southern slope of Qilian Mountain were studied in this study. The soil was divided into sand (2 000-50 μm), silt (2-50 μm) and clay (<2 μm) using centrifugation, and the content of soil particulate organic carbon (POC), distribution of soil POC and stable isotopic composition (δ13C) of POC were analyzed. The results showed that both types of restoration land could increase the content of POC, sand organic carbon was the main part of the newly increased POC in the restoration grassland, and silt and clay organic carbon was the main part in the restoration woodland. With the decrease of soil particle size, the δ13C values increased gradually, the regression slope (K) of δ13C value and LOG (POC) decreased with decreasing particle size. The fractionation range of δ13C value of leaf and topsoil in restoration woodland was higher than that in restoration grassland, while the fractionation range of δ13C value of root and topsoil organic carbon was lower than that in restoration grassland. The average turnover time of sand, silt and clay organic carbon in the restored grassland was 9 a, 20 and 34 a, and that in the restored forest land was 20 a, 29 a and 94 a, respectively. The turnover time of three kinds of particulate organic carbon in the two restoration lands increased with the increase of restoration years. In conclusion, the decomposition degree and turnover rate of soil POC increased with the decrease of particle size. In the process of conversion from leaves to clay organic carbon, the turnover rate of restored forest was faster, and in the process of conversion from root to clay organic carbon, the restoration of grassland was faster.

Key words: organic carbon isotopes, ecological restoration, particulate organic carbon turnover

CLC Number: