Soil carbon is an important component of the global carbon cycle and consists of organic carbon (SOC) and inorganic carbon (SIC) pools. Although SIC has been recognized as a large pool, little is known about how it has been influenced by climate change and land degradation on a decadal timescale. Here, we evaluated the magnitude of the SIC stock and detected its changes under different land cover types across the Tibetan Plateau over the past decades based on repeated SIC measurements in the 1980s and 2020s at the same sites. In the soils of the Tibetan Plateau, SIC accounts for 45% and 49% of the total (organic plus inorganic) soil carbon at depths of 0–50 cm and 0–100 cm, with estimated SIC stocks of approximately 15.6 and 20.9 Pg C, and average SIC densities of 7.2 and 9.4 kg C m, respectively. Partial correlation and variation partitioning analyses revealed that the spatial distribution of SIC was predominantly influenced by soil properties (soil type, texture, and pH) and climate, explaining 12.1% and 7.5% of the SIC variance, respectively. Between the 1980s and the 2020s, an overall accumulation of SIC was observed for all land cover types, with an average increase of 2.3 and 2.0 g C kg for the topsoil (notably 0–20 cm) and subsoil (notably 20–50 cm), respectively. However, the response of SIC to a changing climate is more nuanced; increased precipitation may reduce SIC stock in arid areas by enhancing leaching, whereas warming temperatures may contribute to SIC accumulation in humid regions. Overall, these findings have important implications for understanding the role of SIC in the global carbon cycle under future climate change events.

中文翻译：

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1980-2020年代青藏高原土壤无机碳储量及其变化

土壤碳是全球碳循环的重要组成部分，由有机碳（SOC）和无机碳（SIC）库组成。尽管 SIC 被认为是一个大池，但人们对它在十年时间尺度上如何受到气候变化和土地退化的影响知之甚少。在这里，我们根据 1980 年代和 2020 年代在同一地点重复的 SIC 测量，评估了 SIC 库的大小，并检测了过去几十年青藏高原不同土地覆盖类型下 SIC 库的变化。在青藏高原土壤中，SIC 占 0-50 cm 和 0-100 cm 深度土壤总碳（有机加无机）的 45% 和 49%，估计 SIC 储量约为 15.6 和 20.9 Pg C ，平均 SIC 密度分别为 7.2 和 9.4 kg C m 。偏相关和变异划分分析表明，SIC 的空间分布主要受土壤性质（土壤类型、质地和 pH 值）和气候的影响，分别解释了 SIC 方差的 12.1% 和 7.5%。在 1980 年代至 2020 年代之间，所有土地覆盖类型都观察到 SIC 的总体积累，表土（尤其是 0-20 厘米）和底土（尤其是 20-50 厘米）平均增加了 2.3 和 2.0 g C kg ， 分别。然而，SIC 对气候变化的反应更加微妙；降水量增加可能会通过增强淋滤来减少干旱地区的碳化硅库存，而气温升高可能会导致潮湿地区碳化硅的积累。总体而言，这些发现对于理解未来气候变化事件下 SIC 在全球碳循环中的作用具有重要意义。