Abstract An understanding of the global terrestrial carbon cycle is crucial to predict future climate change. Deserts are an important part of the terrestrial ecosystem, but their role in the terrestrial carbon cycle has long been neglected. Recent studies have shown that deserts may sequester enormous volumes of CO2 and play a pivotal role as a carbon sink. As the world’s second-largest shifting desert, the Taklimakan Desert (TD) contributes substantially to the global desert carbon sink. However, the contributions of the internal processes of the TD to its carbon sink and the long-term trend of the carbon sink under climate change are still unclear. Based on an observational study, we determined that both the expansion/contraction of soil air containing CO2 caused by heat fluctuation in shifting sand and the salt/alkali chemistry control the release/absorption processes of soil respiration in shifting sand. Besides, the mutual offset of these processes indicates that the shifting sand in the TD acts as a stable carbon sink at present, with an annual average CO2 uptake rate of 7.11 g m−2. However, an increase in soil temperature difference will stimulate soil air expansion and release more CO2 into the atmosphere under climate change, gradually lessening the carbon sink rate of shifting sand in TD in the future. These processes will be accelerated by a positive feedback loop, where this effect triggered by climate change will enhance regional warming. Our results highlight the status of deserts in the global carbon cycle and provide crucial information regarding the world’s missing carbon sink.

中文翻译：

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土壤温度差异对沙漠碳汇的影响

摘要 了解全球陆地碳循环对于预测未来气候变化至关重要。沙漠是陆地生态系统的重要组成部分，但其在陆地碳循环中的作用长期被忽视。最近的研究表明，沙漠可能会封存大量的二氧化碳，并作为碳汇发挥关键作用。作为世界第二大流动沙漠，塔克拉玛干沙漠 (TD) 对全球沙漠碳汇做出了重大贡献。然而，TD内部过程对其碳汇的贡献以及气候变化下碳汇的长期趋势尚不清楚。根据一项观察性研究，我们确定流沙中热波动引起的含 CO2 土壤空气的膨胀/收缩和盐/碱化学控制了流沙中土壤呼吸的释放/吸收过程。此外，这些过程的相互抵消表明，目前TD流沙作为一个稳定的碳汇，年平均CO2吸收率为7.11 g m-2。然而，在气候变化下，土壤温差的增加会刺激土壤空气膨胀，释放更多的CO2到大气中，从而逐渐降低未来TD流沙的碳汇率。这些过程将通过正反馈循环加速，气候变化引发的这种效应将加剧区域变暖。