腾格里沙漠东南缘人工固沙植被区表层土壤有机碳矿化对凋落物添加的响应

土壤有机碳矿化是调控土壤碳库时空格局、土壤碳收支平衡和植物养分供应的重要过程，植物残体和凋落物分解释放CO₂直接影响着土壤有机碳矿化。研究了不同类型凋落物对腾格里沙漠东南缘建植于1956年的人工固沙植被区土壤有机碳矿化过程及其对水分和温度的响应特征。结果表明：凋落物添加显著促进了有机碳矿化，添加柠条锦鸡儿（Caragana korshinskii）、油蒿（Artemisia ordosica）、小画眉草（Eragrostis minor）凋落物后，CO₂-C最大矿化速率分别增大了6.94、5.17、3.46倍，0~5 cm层土壤是5~10 cm层土壤的1.09、1.55、1.22倍；CO₂-C累积释放量分别增加了3.73、3.38、2.34倍，0~5 cm层土壤是5~10 cm层土壤的1.17、1.30、1.57倍。凋落物对有机碳矿化的促进作用与温度和水分密切相关，25℃时，CO₂-C平均释放速率、最大释放速率、累积碳释放量分别是10℃的2.21、3.60、2.21倍，而含水量10%时，CO₂-C平均释放速率、最大释放速率和累积碳释放量分别是含水量5%时的1.25、1.20、1.25倍。相关性分析表明，凋落物碳氮含量、碳氮比、木质素比氮和土壤有机碳以及全氮是影响有机碳矿化的主要因子。凋落添加土壤后潜在可矿化碳表现为柠条锦鸡儿>油蒿>小画眉草>对照。凋落物添加显著促进了有机碳矿化过程及碳周转，植被恢复过程中草本植物凋落物的输入更有利于土壤碳固存，凋落物对土壤碳库的调控作用受土壤理化性质和水热等环境因子的共同作用影响。

Response of Topsoil Organic Carbon Mineralization to Litter Addition in the Revegetation Area in the Southeastern Fringe of the Tengger Desert

The mineralization of soil organic carbon is an important process that regulates the spatial and temporal pattern of soil carbon pool, balance of soil carbon budget, and nutrient availability for soil biota and plants, decomposition of plant residues and litter and releases CO₂ directly affects soil organic carbon mineralization (SOCM). SOCM process and its response to soil water content (SWC) and soil temperature (T_s) in the revegetation area of established in 1956 in the southeastern margin of the Tengger Desert were studied by different types of litter addition. The results showed that the addition of litter significantly promoted SOCM. After adding Caragana korshinskii, Artemisia ordosica litter and Eragrostis minor litter, the maximum rate of SOCM increased by 6.94, 5.17 times and 3.46 times respectively, the soil of 0-5 cm layer is 1.09, 1.55 and 1.22 times of the soil of 5-10 cm layer; the cumulative carbon release (CCR) increased by 3.73, 3.38 times and 2.34 times, and the soil of 0-5 cm layer is 1.17, 1.30 and 1.57 times of the soil of 5-10 cm layer. The effect of litter on SOCM was closely related to SWC and T_s. The average and maximum SOCM rate and CCR in 25℃ incubation were 2.21 times, 3.60 times and 2.21 times than great than those soil in 10℃, respectively. The average and maximum SOCM rate and CCR with 10% of SWC were 1.25 times, 1.20 times and 1.25 times than those with 5%. Litter organic carbon, litter nitrogen, Litter carbon to nitrogen ratio, Litter lignin to nitrogen ratio and soil organic carbon and nitrogen are the main factors affecting SOCM. The soil potential mineralizable carbon in different types litter addition was expressed as Caragana korshinskii > Artemisia ordosica > Eragrostis minor > Control. The addition of litter significantly promoted the process of SOCM and soil carbon turnover. The input of herbaceous litter during vegetation restoration was more conducive to soil carbon sequestration, and the regulation by litter on soil carbon pool attributes in combination with soil physicochemical properties and SWC and T_s.