Xu Ren-Fei, Wang Lu, Deng Lei, Wang Wen-Ying, DU Sheng, Guan Jin-Hong
School of Life Science, Qinghai Normal University/Academy of Plateau Science and Sustainability, Xining 810008, China.
Key Laboratory of Biodiversity Formation Mechanism and Comprehensive Utilization of the Qinghai-Tibetan Plateau in Qinghai Province, Xining 810008, China.
Ying Yong Sheng Tai Xue Bao. 2024 Oct;35(10):2657-2666. doi: 10.13287/j.1001-9332.202410.002.
As the most effective way to remedy and reconstruct the degraded ecosystems, vegetation restoration could affect soil carbon and nitrogen cycles and water balance. We examined the responses of carbon, nitrogen, and water in 0-200 cm soil layer to vegetation restoration years by analyzing their distribution characteristics across a restoration chronosequence of plantation (5, 10, 15, 20, and 25 years) in alpine sandy region of the Qinghai-Tibetan Plateau. The results showed that the content and storage of soil organic carbon (SOC) and soil total nitrogen (STN) increased significantly, while that of soil inorganic carbon (SIC) decreased significantly with restoration years. SOC, SIC and STN content for the entire 200 cm soil layer were 0.41-1.24 g C·kg, 4.53-8.07 g C·kg, and 0.12-0.22 g N·kg, respectively. SOC, SIC, and STN storage for the entire 200 cm were 16.08-33.51 t C·hm, 187.12-241.02 t C·hm, and 4.27-6.66 t N·hm, respectively. After 25 years vegetation restoration, the storage of SOC and STN for the entire 200 cm soil layer were significantly increased by 68.1% and 39.6%, while the SIC storage was significantly decreased by 9.5% compared with the 5 years vegetation restoration. The storage of SOC, SIC and STN in the 100-200 cm soil layer were 1.3-1.4 times higher than those in the 0-100 cm layer. The storage of SIC within the 0-200 cm layer was 8.2 times of the SOC storage over the same layer. Compared with the 5 years restoration, SOC storage in the 0-200 cm soil layer of 10, 15, 20, and 25 restoration years increased by 13.3%-68.1%, which were 1.0-2.1 times of the STN storage, suggesting a decoupling of SOC and STN accumulation during restoration. After 15 years vegetation restoration, soil water content and storage peaked at 7.4% and 274.17 mm, respectively. Restoration years were significantly positively correlated with SOC and STN contents, but not related to water content. SOC, STN, and water storage were significantly and positively correlated with each other, resulting in a positive promoting effect between each pair. In conclusion, the inorganic carbon pool was a significant contributor to the total carbon pool in alpine sandy region of the Qinghai-Tibetan Pla-teau. Vegetation restoration year is a primary determinant of soil carbon, nitrogen, and water sequestration, with the contributions of deeper soil layers to regional levels being equally important and can not be ignored. This finding suggested that alpine sandy ecosystems required soil nitrogen input in the early vegetation restoration stages.
作为修复和重建退化生态系统的最有效方法，植被恢复会影响土壤碳氮循环和水平衡。我们通过分析青藏高原高寒沙地人工林（5年、10年、15年、20年和25年）恢复时间序列上土壤碳、氮和水在0 - 200厘米土层中的分布特征，研究了它们对植被恢复年限的响应。结果表明，随着恢复年限的增加，土壤有机碳（SOC）和土壤全氮（STN）的含量和储量显著增加，而土壤无机碳（SIC）的含量显著下降。整个200厘米土层的SOC、SIC和STN含量分别为0.41 - 1.24克碳·千克、4.53 - 8.07克碳·千克和0.12 - 0.22克氮·千克。整个200厘米土层的SOC、SIC和STN储量分别为16.08 - 33.51吨碳·公顷、187.12 - 241.02吨碳·公顷和4.27 - 6.66吨氮·公顷。植被恢复25年后，与5年植被恢复相比，整个200厘米土层的SOC和STN储量分别显著增加了68.1%和39.6%，而SIC储量显著下降了9.5%。100 - 200厘米土层的SOC、SIC和STN储量比0 - 100厘米土层高1.3 - 1.4倍。0 - 200厘米土层内SIC储量是同层SOC储量的8.2倍。与5年恢复相比，10年、15年、20年和25年恢复年限的0 - 200厘米土层SOC储量增加了13.3% - 68.1%，是STN储量的1.0 - 2.1倍，表明恢复过程中SOC和STN积累出现解耦。植被恢复15年后，土壤含水量和储量分别在7.4%和274.17毫米处达到峰值。恢复年限与SOC和STN含量显著正相关，但与含水量无关。SOC、STN和储水量之间显著正相关，两两之间产生正促进作用。总之，无机碳库是青藏高原高寒沙地总碳库的重要贡献者。植被恢复年限是土壤碳、氮和水分固存的主要决定因素，深层土壤层对区域水平的贡献同样重要且不可忽视。这一发现表明，高寒沙地生态系统在植被恢复早期需要输入土壤氮素。
