摘要:多年冻土区土壤碳库对水热变化的响应是气候预测中的主要不确定性因素。国内外关于浅层土壤（0-30 cm）有机碳储量及潜在排放量的研究已取得一系列突破成果，然而深层土壤对气候变暖作何响应仍需进一步探讨。利用钻孔技术采集大兴安岭北部多年冻土区0-6 m（含活动层和多年冻土层）土壤样品，探究土壤碳、氮、磷等理化指标的剖面分布特征，设置三种温度（5、10和15℃）及水分（30%、45%和60%）梯度的室内培养实验，明确多年冻土区不同深度土壤有机碳矿化对气候变化的响应特征。结果表明，土壤pH、总有机碳、溶解性有机碳、总氮、硝态氮、铵态氮含量均与土壤深度呈显著正相关，多年冻土层中的平均储量高于活动层。培养60天后，各深度土壤有机碳累积矿化量的变化范围为0.20-4.86 mg C。整体来看，土壤有机碳累积矿化量随温度的升高而增加，但其对水分变化的响应较为复杂，表现出先减小（幅度较大）后增大（幅度较小）的趋势。分析不同深度土壤有机碳累积矿化量，发现多年冻土层平均值显著高于活动层。三因素方差分析结果表明，温度、水分和深度及交互作用对累积矿化量影响显著（P<0.001）。活动层Q₁₀平均值为2.46，多年冻土层顶部出现极低值，多年冻土层Q₁₀平均值为1.91，两者的差值随着水分增大而减小。土壤性状及有机质的垂直分异是多年冻土区土壤有机碳累积矿化量及其温度敏感性在深度上显现差异的主要原因。



Abstract:The response of soil carbon to hydrothermal dynamic in permafrost regions is a major uncertainty factor in projections of climate. A series of breakthroughs have been made on organic carbon storage and potential emission in shallow soil (0-30 cm) in China and abroad, however, the response of deep soil to climate warming in future merit more consideration. This study used soil cores from 0-6 m (including active layer and permafrost layer), which were drilled in the northern slope of the Great Hing'an Mountains, to explore the profile characteristics of soil carbon, nitrogen and phosphorus contents. Three temperature (T, 5℃, 10℃ and 15℃) and moisture (W, 30%, 45% and 60%) treatment were set to clarify the feedback of soil organic carbon mineralization at different depths in permafrost regions to climate change. The results showed that the values of pH, soil organic carbon, dissolved organic carbon, total nitrogen, nitrate nitrogen, and ammonium nitrogen were positively correlated with soil depth, and the average reserves in permafrost layer were higher than that in active layer. After 60 days of incubation experiment, the total carbon mineralization ranged from 0.20 to 4.86 mg C under the treatments for all samples. On the whole, the increase in temperature promoted the accumulative mineralization of soil organic carbon. The influence mechanism of soil moisture on soil organic carbon was complex, and the mineralization showed a trend of decreasing first and then increasing with the increase of soil moisture. By analyzing the mineralization of soil organic carbon at different depths, we found that the average value in the deep permafrost layer was significantly higher than that in active layer. Three-way ANOVA showed that depth, temperature, moisture and interaction had significant effects on the mineralization of soil organic carbon (P<0.001). The average value of Q₁₀ of active layer and permafrost layer were 2.46 and 1.91 respectively, which showed the lowest values at the top layer of the permafrost soil. The difference between active layer and permafrost layer was smaller with the increase of moisture. Due to the vertical differentiation of soil properties and organic matter, the total carbon mineralization and Q₁₀ values varied with depth in permafrost regions.





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