Xian Hai-Ying, Xiao Bo, Yao Xiao-Meng, Dou Wei-Qiang
College of Land Science and Technology, China Agricultural University/Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2025 Jan 18;36(1):132-140. doi: 10.13287/j.1001-9332.202501.012.
The intensification of global climate change may increase temperature and precipitation in drylands. Biocrust is one of the important surface covers in drylands. The responses of soil organic carbon (SOC) fractions and their stability in biocrusts-covered soil to climate warming and wetting remain unclear. We investigated the response of SOC fractions and stability under moss-dominated biocrusts in the Loess Plateau to two years warming (approximately 3 ℃ increase) crossed with 10%, 30% and 50% increases in precipitation. The results showed that: 1)The contents of SOC and its fractions in the surface layer covered by moss biocrusts were significantly increased by both warming and warming combined with wetting, whereas SOC stability was decreased. Both warming and warming combined with wetting increased the contents of SOC, labile organic carbon (LOC, including microbial biomass carbon, dissolved organic carbon and easily oxidized organic carbon) and recalcitrant organic carbon (ROC) by 28%, 51% and 24% on average, respectively. They also increased the labile index of organic carbon (LIC) by an average of 28%. In contrast to only warming, the treatments that combined warming and wetting resulted in average increases in SOC, LOC and ROC of 25%, 30% and 22%, together with a 15% rise in LIC. 2) There were significant and positive correlations between the contents of SOC, LOC and ROC and biocrust cover, moss biomass, moss density, and ammonium and nitrate contents under simulated warming and wetting. Furthermore, annual precipita-tion accounted for an average of 88% of the variation in SOC components. In conclusion, the warming and wetting climate changed the carbon conversion strategies of biocrusts, increased the content and activity of SOC components and decreased SOC stability. Therefore, in future intensified warming and wetting scenarios, SOC content in moss-dominated biocrust-covered soils in the Loess Plateau region may increase, with more pronounced dynamic changes in soil carbon pools.
全球气候变化加剧可能会使干旱地区的温度升高、降水增加。生物结皮是干旱地区重要的地表覆盖物之一。生物结皮覆盖土壤中土壤有机碳（SOC）组分及其稳定性对气候变暖和湿润的响应仍不清楚。我们研究了黄土高原以苔藓为主的生物结皮覆盖下的土壤有机碳组分及其稳定性对两年增温（约升高3℃）与降水分别增加10%、30%和50%的响应。结果表明：1）苔藓生物结皮覆盖的表层土壤中，增温以及增温与湿润相结合均显著增加了土壤有机碳及其组分的含量，但土壤有机碳稳定性降低。增温以及增温与湿润相结合平均分别使土壤有机碳、活性有机碳（LOC，包括微生物生物量碳、溶解有机碳和易氧化有机碳）和难分解有机碳（ROC）的含量增加了28%、51%和24%。它们还使有机碳的活性指数（LIC）平均增加了28%。与仅增温相比，增温与湿润相结合的处理使土壤有机碳、活性有机碳和难分解有机碳平均分别增加了25%、30%和22%，活性指数增加了15%。2）在模拟的增温和湿润条件下，土壤有机碳、活性有机碳和难分解有机碳的含量与生物结皮盖度、苔藓生物量、苔藓密度以及铵态氮和硝态氮含量之间存在显著正相关。此外，年降水量平均解释了土壤有机碳组分变异的88%。总之，气候变暖和湿润改变了生物结皮的碳转化策略，增加了土壤有机碳组分的含量和活性，降低了土壤有机碳稳定性。因此，在未来气候变暖和湿润加剧的情景下，黄土高原地区以苔藓为主的生物结皮覆盖土壤中的土壤有机碳含量可能增加，土壤碳库的动态变化将更加显著。
