Wang Zhufeng, Wang Yugang, Feng Wenting
State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China; University of Chinese Academy of Sciences, Beijing 100049, China; Fukang Station of Desert Ecology, Chinese Academy of Sciences, Fukang, Xinjiang 831505, China.
Chemosphere. 2023 Jun;325:138319. doi: 10.1016/j.chemosphere.2023.138319. Epub 2023 Mar 8.
Soil inorganic carbon (SIC) accounts for 30-70% of the total soil C in global drylands. Despite the slow turnover rate, recent studies indicate that SIC could be altered by land-use change as soil organic C (SOC). Neglecting SIC change could contribute greatly to the uncertainty of soil C dynamics in drylands. However, due to the spatial-temporal variation in SIC, the direction and magnitude of SIC change (rate) induced by land-use change at a large spatial scale is understudied and poorly understood. Here, we used the space-for-time approach to test how the SIC change varied with the duration and type of land-use change and soil depth across China's drylands. We assessed the temporal and spatial variations in the SIC change rate and explored the influencing factors based on a regional dataset comprising 424 pairs of data across North China. We found that the SIC change rate of 0-200 cm after land-use change was 12.80 (5.47‒20.03) g C m yr (mean with 95% confidence interval), which was comparable to the SOC change rate (14.72, (5.27-24.15 g C m yr)). Increased SIC occurred only in deep soils (>30 cm) and in the conversion from deserts to croplands or woodlands. In addition, the SIC change rate decreased with the duration of land-use change, implying that quantifying the temporal pattern of SIC change is necessary to accurately estimate SIC dynamics. The SIC change was strongly related to changes in soil water content. The SIC change rate was weakly and negatively correlated with the SOC change rate, and this relationship varied with soil depth. Together, this study highlights that to improve the prediction of soil C dynamics following land-use change in drylands, we should quantify the temporal and vertical patterns of both soil inorganic and organic C changes in the region.
土壤无机碳（SIC）占全球旱地土壤总碳的30%-70%。尽管周转速率缓慢，但最近的研究表明，SIC可能会像土壤有机碳（SOC）一样因土地利用变化而改变。忽视SIC变化可能会极大地增加旱地土壤碳动态的不确定性。然而，由于SIC的时空变化，在大空间尺度上土地利用变化引起的SIC变化（速率）的方向和幅度尚未得到充分研究，人们对此了解甚少。在此，我们采用空间换时间的方法，来检验中国旱地SIC变化如何随土地利用变化的持续时间和类型以及土壤深度而变化。我们基于一个包含中国北方424对数据的区域数据集，评估了SIC变化速率的时空变化，并探究了影响因素。我们发现，土地利用变化后0-200厘米深度的SIC变化速率为12.80（5.47-20.03）克碳/平方米·年（均值及95%置信区间），这与SOC变化速率（14.72，（5.27-24.15）克碳/平方米·年）相当。SIC增加仅发生在深层土壤（>30厘米）以及从沙漠转变为农田或林地的过程中。此外，SIC变化速率随土地利用变化的持续时间而降低，这意味着量化SIC变化的时间模式对于准确估计SIC动态是必要的。SIC变化与土壤含水量的变化密切相关。SIC变化速率与SOC变化速率呈弱负相关，且这种关系随土壤深度而变化。总之，本研究强调，为了改进对旱地土地利用变化后土壤碳动态的预测，我们应该量化该区域土壤无机碳和有机碳变化的时间和垂直模式。
