In desert ecosystems, afforestation with xerophytic shrubs has the potential to significantly increase soil nutrient levels by mitigating wind and soil erosion. Nevertheless, further investigation is required to elucidate the changes in soil organic carbon (SOC) fractions and stability on different soil depths with afforestation years. We collected soil samples from the 0–20, 20–60, and 60–100 cm depths of three xerophytic shrublands ages (3, 7, and 10 years), with a natural desert as the control, in a hyper‐arid desert region. We investigated the variations of SOC fractions (stable and active C) and stability (stability index and MAOC:POC ratios) after afforestation. The results showed that the rate of increase in SOC fractions and stability did not follow a linear trajectory with afforestation years. Instead, they accelerated around 7 years but then decreased after 10 years. The increase in SOC stability was primarily attributed to the greater increase in stable C within the total SOC pool. Afforestation increased the concentration of ROC from 0.26 to 0.89 g kg−1 and MAOC from 0.11 to 0.78 g kg−1. Afforestation increased SOC stability by 74.36%–231% compared to the CK in the 0–100 cm. SOC stability in the 60–100 cm was higher than that in the 0–20 cm layer, while SOC stability varied insignificantly across soil layers. The strongest direct positive impact on SOC stability was attributed to changes in soil physicochemical properties rather than soil microbial biomass or aggregate stability. These findings contribute to our understanding of the importance of afforestation in increasing SOC stability in desert ecosystems.

中文翻译：

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旱生灌木造林促进了荒漠超干旱环境中土壤有机碳的稳定性


在沙漠生态系统中，旱生灌木造林有可能通过减轻风和土壤侵蚀来显着提高土壤养分水平。然而，需要进一步研究以阐明不同土壤深度上土壤有机碳 （SOC） 组分和稳定性随造林年限的变化。我们从三个旱生灌木丛年龄（3、7 和 10 年）的 0-20、20-60 和 60-100 厘米深度收集土壤样本，以天然沙漠为对照，位于极度干旱的沙漠地区。我们研究了造林后 SOC 分数 （稳定和活性 C） 和稳定性 （稳定性指数和 MAOC：POC 比率） 的变化。结果表明，SOC 分数和稳定性的增加率不遵循造林年份的线性轨迹。相反，它们在 7 年左右加速，但在 10 年后下降。SOC 稳定性的增加主要归因于总 SOC 池中稳定 C 的更大增加。植树造林使 ROC 的浓度从 0.26 增加到 0.89 g kg-1，MAOC 的浓度从 0.11 增加到 0.78 g kg-1。与 CK 相比，造林使 0—100 cm 土壤有机碳稳定性提高了 74.36%–231%，60—100 cm 土层的土壤有机碳稳定性高于 0—20 cm 土层，而土壤有机碳稳定性在不同土层间差异不显著。对土壤有机碳稳定性的直接正影响最强的是土壤理化性质的变化，而不是土壤微生物量或团聚体稳定性的变化。这些发现有助于我们理解植树造林在提高沙漠生态系统 SOC 稳定性方面的重要性。