基于137Cs的青藏高原高寒草甸土壤侵蚀及碳流失估算

[目的] 定量分析青藏高原高寒草甸土壤侵蚀状况及其伴随的碳流失，为全面评估土壤侵蚀影响，实施有效水土保持措施提供参考。[方法] 结合¹³⁷Cs示踪技术与前人研究，对青藏高原高寒草甸土壤的整体侵蚀水平及其土壤有机碳流失进行了估算。[结果] 未受人为扰动的高寒草甸土壤自上而下表现出3个层次(A，B和C层)的理化性质特征，其¹³⁷Cs分布遵循显著指数递减模式。目前，高原草甸土壤年均侵蚀模数约为77~230 t/km²，推测其每年直接导致的土壤有机碳损失量平均不低于4.86 t/km²。[结论] 青藏高原高寒草甸土壤侵蚀水平整体较弱，但因土壤侵蚀流失的有机碳不容忽视。在未来气候变化背景下，升温导致的土壤湿度下降对植被生长的限制，以及人类活动的影响，较大可能成为诱使青藏高原草甸土壤退化和有机碳流失的潜在因素。

137Cs-based Estimation of Soil Erosion and Organic Carbon Loss in Alpine Meadow Soil on Tibetan Plateau

[Objective] Soil erosion and its associated carbon loss in an alpine meadow on the Tibetan Plateau were quantitatively analyzed in order to provide a reference for comprehensively evaluating the impact of soil erosion and for implementing effective soil and water conservation measures.[Methods] We used ¹³⁷Cs tracing technology combined with the results of previous research studies to determine erosion rate and consequent carbon loss for an undisturbed alpine meadow soil on the Tibetan Plateau.[Results] The undisturbed meadow soil exhibited three distinct layers (A, B, and C) of physiochemical properties, and the distribution of ¹³⁷Cs declined exponentially with increasing soil depth. The recent erosion rate of the alpine meadow soil was about 77-230 t/(km²·yr), and was estimated to result in an average annual soil organic carbon loss of not less than 4.86 t/km².[Conclusion] Even though the overall soil erosion rate of the alpine meadow on the Tibetan Plateau was low, it''s organic carbon loss due to erosion cannot be underestimated. Both increased human activities and reduced meadow growth due to decreased soil moisture under future global warming are likely to result in further soil degradation and soil organic carbon loss in alpine meadows.