土壤CO₂是岩溶碳循环的核心驱动因子之一。以广西桂林丫吉岩溶试验场土壤剖面为例，利用高分辨率监测技术对不同土壤深度的温度、水分和CO₂进行监测，解析土壤剖面中CO₂含量的动态变化机理及其影响因素。季节尺度上，土壤温度是影响土壤CO₂含量的主要因素。土壤温度与大气温度变化趋势一致，表层土壤有明显的昼夜变化，而深层土壤则表现出多日连续性变化。在长时间尺度下，土壤温度越高，土壤CO₂含量也越高。短时间尺度上，土壤水分则是影响土壤CO₂含量的主要因素。降水前，土壤水分较低，降水后会刺激土壤CO₂以脉冲形式释放；而土壤水分较高时，降水则会降低土壤CO₂含量。特别是在干旱条件下，降水能够显著提高土壤CO₂含量，称为“桦木效应”。降水情景下，不同降水强度对土壤CO₂含量的影响不同。短时强降水后，土下10 cm处的CO₂含量（CO₂-10）迅速升高，土下40、90 cm处的CO₂含量（CO₂-40、CO₂-90）变化较小。持续性降水则会导致表层CO₂-10先升高后降低，CO₂-90逐渐减少。土壤CO₂含量的变化还受到土壤分层特性的影响。表层土壤植物根系密集，CO₂含量较高；而深层土壤孔隙度小、扩散性低，CO₂含量随深度增加而升高。本研究结果可为全球岩溶碳循环研究提供科学指导。

Soil CO₂ is a key driving factor in the karst carbon cycle. The soil profile of Yaji karst test site in Guilin, Guangxi Province was selected as a case study. High-resolution monitoring technology was employed to measure temperature, moisture, and CO₂ levels at various soil depths. The analysis focused on the dynamic mechanisms and influencing factors of CO₂ content within the soil profile. At the seasonal scale, soil temperature is the primary factor influencing soil CO₂ concentration. Soil temperature corresponded with atmospheric temperature, exhibiting pronounced diurnal variations at the surface level, while deeper soil layers displayed continuous changes over multiple days. On long time scales, higher soil temperatures correspond to increased soil CO₂ concentrations. Conversely, on shorter time scales, soil moisture is the primary factor affecting soil CO₂ levels. Prior to precipitation, soil moisture levels are low. Following precipitation, soil CO₂ is released in pulses. Conversely, when soil moisture is high, precipitation results in a decrease in soil CO₂ content. Notably, under drought conditions, precipitation can substantially elevate soil CO₂ levels, a phenomenon known as the "birch effect". Under varying precipitation scenarios, different precipitation intensities exert distinct effects on soil CO₂ content. Following a brief period of heavy rainfall, CO₂-10 levels increased rapidly, while CO₂-40 and CO₂-90 exhibited minimal changes. Prolonged precipitation resulted in an initial rise in CO₂-10, followed by a decline, whereas CO₂-90 gradually decreased. Changes in soil CO₂ content are influenced by the characteristics of soil stratification. The root systems of plants in the topsoil are dense, resulting in elevated CO₂ levels. Conversely, deep soils exhibit low porosity and diffusion rates, leading to an increase in CO₂ content with depth. The findings provide scientific guidance for understanding the global karst carbon cycle.