为阐明库布齐沙漠植被恢复过程中土壤碳通量的时空动态特征及主控因子，明确土壤有机碳含量和储量的变化趋势，本研究以流动沙地、半固定沙地、藻结皮固定沙地和地衣苔藓混合结皮固定沙地为研究对象，运用静态暗箱–气相色谱法对风沙土壤碳通量及水热因子进行观测，并对土壤有机碳含量和密度进行测定和计算。结果表明，生长季内风沙土壤碳通量变异较大，季节动态与土壤温度基本一致，且随植被恢复碳通量呈递增趋势：混合结皮固定沙地（210.28 mg/（m²·h））>藻结皮固定沙地（177.45 mg/（m²·h））>半固定沙地（117.34 mg/（m²·h））>流动沙地（65.61 mg/（m²·h））；土壤碳通量与各层土壤温度均显著正相关，除流动沙地土壤碳通量与深层土壤含水量显著负相关外，其余样地碳通量均与表层土壤含水量显著负相关；风沙土壤有机碳含量和密度随植被恢复而递增：混合结皮固定沙地（1.32 g/kg，0.94 kg/m²）>藻结皮固定沙地（1.03 g/kg，0.74 kg/m²）>半固定沙地（0.45 g/kg，0.36 kg/m²）>流动沙地（0.27 g/kg，0.24 kg/m²），且均具有明显的随土层加深有机碳含量和密度逐渐降低的趋势；荒漠土壤表面CO₂年通量与0~10 cm和10~20 cm土层有机碳密度显著正相关（P< 0.05）。综上表明，人工建植促进植被恢复和沙地固定，增加风沙土壤碳排放通量，显著提高风沙土壤碳贮存能力和潜力，改变荒漠生态系统碳循环格局。

In order to investigate the spatio-temporal dynamic characteristics and the main controlling factors of soil CO₂ flux during the process of vegetation restoration in Hobq desert, and clarify the variation trend of soil organic carbon content and density, the mobile dune, semi-fixed sand, algal crust fixed sand and mixed crust fixed sand were taken as the object, and soil CO₂ flux, temperature and moisture were continuously measured using the static closed chamber-gas chromatography technique, and the content and density of soil organic carbon were measured and calculated. The results showed that in the growing season, the spatial and temporal variation of soil CO₂ flux was obvious and increased with vegetation restoration, CO₂ flux was in an order of mixed crust fixed sand (210.28 mg/(m²·h)) > algal crust fixed sand (177.45 mg/(m²·h)) > semi-fixed sand (117.34 mg/(m²·h)) mobile dune (65.61 mg/(m²·h)). Soil CO₂ flux of the four sites were significantly positively correlated with soil temperature. CO₂ flux of mobile dune was significantly negatively correlated with deep soil moisture, and were significantly negatively correlated with surface soil moisture in other sites. Soil organic carbon content density also increased with vegetation restoration:mixed crust fixed sand (1.32 g/kg, 0.94 kg/m²) algal crust fixed sand (1.03 g/kg, 0.74 kg/m²) > semi-fixed sand (0.45 g/kg, 0.36 kg/m²) > mobile dune (0.27 g/kg, 0.24 kg/m²). Both the content and density of organic carbon decreased with soil depth. Soil surface carbon flux was significantly positively correlated with organic carbon density at the depths of 0-10 cm and 10-20 cm. The above results demonstrated that artificial planting could promote vegetation restoration and sand fixation, which effectively improved carbon emission flux of sandy soil, moreover, significantly increased carbon storage capacity and potential, thus could alter carbon cycle pattern of desert ecosystems.

S157.2

蒙古国基础地理要素与土地利用/土地覆被调查项目（2017FY101301-4）资助。