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The contribution of saline-alkali land to the terrestrial carbon stock balance
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  • Yuefen Li,
  • Lei Chang,
  • Tianhang Ju,
  • Jialin Zhang,
  • Xingyi Wang,
  • Jingfa Zhong,
  • Haoye Li,
  • Shuran Jia,
  • Keyi Zhang
Yuefen Li
Jilin University College of Earth Sciences

Corresponding Author:[email protected]

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Lei Chang
Jilin University College of Earth Sciences
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Tianhang Ju
Jilin University College of Earth Sciences
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Jialin Zhang
Jilin Agricultural University
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Xingyi Wang
Jilin University College of Earth Sciences
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Jingfa Zhong
Jilin University College of Earth Sciences
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Haoye Li
Jilin University College of Earth Sciences
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Shuran Jia
Jilin Agricultural University
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Keyi Zhang
Jilin University College of Earth Sciences
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Abstract

Saline-alkali land is an important component of terrestrial ecosystems and may serve as a carbon sink but its net contribution to the overall terrestrial carbon sink is unknown. Using methods recommended by the IPCC, this study evaluates the impacts of interconverting saline-alkali and non-saline-alkali land on terrestrial carbon stocks by measuring two major carbon pools (soil organic carbon and vegetation biocarbon) in the saline-alkali land of China’s Songnen Plain. Distinct phases in the evolution of the region’s terrestrial carbon stock were delineated, factors contributing to transitions between phases were identified, and effects of changes in the saline-alkali land carbon stock on the overall terrestrial carbon sink were estimated. Between 2005 and 2020, the region’s saline-alkali land carbon stock initially increased, then declined, and finally increased again. However, the overall terrestrial carbon stock decreased by 0.5 Tg (1 Tg=10 9 g), indicating that the increase in the saline-alkali land carbon stock was due primarily to expansion of the saline-alkali land area. The conversion of non-saline-alkali land to saline-alkali land was a carbon-emitting process; consequently, in areas undergoing saline-alkali land change, the lower carbon density bound was equal to the carbon density of unconverted saline-alkali land and the upper bound was equal to the carbon density of unconverted non-saline-alkali land. In general, changes in the carbon stock of saline-alkali land correlated negatively with changes in the overall terrestrial carbon stock. These findings may guide the development of policies for remediating and reclaiming saline-alkali land, especially those relating to land development and carbon sequestration.