Warming promotes soil carbon sequestration in the Tianshan Mountains

Alpine ecosystems are critical components of the global carbon cycle, not only because they store substantial organic carbon, but also due to their high sensitivity to climate change, which has garnered considerable scientific interest. However, under ongoing climate warming, the dynamics and underlying mechanisms of alpine soil organic carbon (SOC) are not yet quantified, thereby introducing uncertainties in predictions of carbon–climate feedbacks. To elucidate the response mechanisms of soil carbon dynamics in alpine ecosystems, this study focuses on the Tianshan Mountains—a representative alpine system in the arid region of Central Asia—through an integrated approach combining field surveys and published data. The results showed that SOC content exhibited a clear altitude-dependent pattern across different vegetation types, and that climate warming generally promoted SOC sequestration in alpine soils. Linear mixed-effects analysis indicated that SOC sequestration may be enhanced via two key mechanisms: (1) warming promotes the accumulation of plant-derived microbial-transformed carbon; and (2) warming promotes carbon stabilization through soil weathering processes. These findings advance our mechanistic understanding of altitudinal SOC dynamics under climate change and provide quantitative evidence that alpine ecosystems act as persistent carbon sinks, which has significant potential for global climate regulation.