【摘要】 青藏高原是我国重要的生态安全屏障，也是我国重大工程建设密集区，重大工程建设（如隧道建设）形成的裸露工程创面改变了土壤结构，可能进一步影响土壤碳素循环，但目前隧道工程创面如何影响土壤有机碳（SOC）尚不清楚.以青藏高原藏东南某隧道工程创面影响区为研究对象，以原生生态系统为对照，从土壤理化性质、SOC组分、团聚体稳定性及土壤酶活性等层面，基于相关性分析和结构方程模型探究隧道工程创面对SOC的影响机制.结果表明，与原生土壤相比，工程创面土壤的SOC、易氧化有机碳、可溶性有机碳、微生物生物量碳及团聚体有机碳分别下降了52.08、25.50、0.05、3.56、10.47 g/kg(P <0.05).工程创面土壤的含水率、营养元素含量、pH值、土壤酶活性以及团聚体稳定性也均呈现下降趋势.结构方程模型分析表明隧道建设通过直接降低土壤团聚体稳定性、土壤酶活性并改变土壤理化性质（有效氮、有效磷、含水率）而降低SOC含量，其中土壤理化性质不仅能直接影响SOC含量，还能通过影响土壤酶活性和团聚体稳定性间接影响SOC含量.综上所述，隧道建设产生的工程创面降低了SOC含量，研究结果为青藏高原隧道建设对SOC影响及制定合理生态保护措施提供了重要理论依据.（图6表5参63）更多还原

【Abstract】 The Qinghai-Xizang Plateau is a vital ecological security barrier in China and a key site for engineering projects, such as tunnel construction. However, these projects can create exposed areas, disrupt the soil structure, and alter the soil carbon cycle. Nevertheless, the effects of tunnel construction on soil organic carbon(SOC) content and the mechanisms involved remain largely unexplored. This study used the original tunnel ecosystem as a control and investigated the influence of tunnel construction on SOC through correlation analysis and structural equation modeling(SEM), focusing on various soil physical and chemical properties.Our findings revealed significant differences between native soil and soil disturbed by construction. Specifically,SOC, easily oxidized organic carbon, dissolved organic carbon, microbial biomass carbon, and aggregate organic carbon in the disturbed soils decreased by 52.08, 25.50, 0.05, 3.56, and 10.47 g/kg, respectively(P <0.05). In addition, tunnel construction reduced the soil moisture, nutrient content, pH, soil enzyme activity, and aggregate stability. SEM analysis revealed that tunnel construction directly impacts soil aggregate stability and soil enzyme activity and alters soil physical and chemical properties, such as available nitrogen, phosphorus,and water content, leading to a decrease in SOC. Additionally, these soil physical and chemical properties not only directly influence SOC content but also indirectly affect soil enzyme activity, further impacting SOC. This study offers crucial insights into the effects of tunnel construction on SOC in the Qinghai-Xizang Plateau and provides a solid foundation for developing effective ecological protection strategies.更多还原