干旱沙区典型人工植被群落下土壤剖面CO_2浓度变化特征及其驱动因子

Soil CO_2 Concentration under Different Types of Plant Communities and the Driving Factors in Arid Desert Area

对人工固沙植被区柠条（Caraganakorshinskii）群落和油蒿（Caraganakorshinskii）群落下不同深度的土壤气体采样，主要研究和讨论了不同类型人下植被区下土壤C02浓度的变化特征及土壤温度和土壤水分对其的影响。结果表明：柠条和油蒿群落0～80cm处的土壤空气C02浓度随着土壤深度的增加而增加，并且在O～40cm，油蒿群落下的土壤c02浓度值大于柠条，而在40cm以下则相反。其平均值分别为1229．3μmol·mol^-1和1242．7μmol·mol^-1，大于同一深度流沙下土壤CO2浓度值978．9μmol·mol^-1。土壤水分与二者的土壤CO2浓度变化趋势在年际尺度上具有一致性，浅层40CN内油蒿群落下的土壤CO2浓度和土壤水分含量的相关性明显大于柠条和流沙。而在40cm以下，则表现为柠条〉油蒿〉流沙。土壤温度对土壤CO2浓度的影响程度一般为流沙〉油蒿〉柠条，特别是流沙，在表层达到了极显著的水平，之后随着土壤深度的增加而降低。而土壤温度对油蒿和柠条样地土壤CO2浓度的影响较为复杂，呈现出先增加后减小的趋势。在年际尺度上，土壤水分含量是不同植被群落下土壤剖面CO2浓度的关键限制因子，而在日尺度上，土壤温度则为主要限制因子。据粗略估计，在0～80cm内，柠条和油蒿根系呼吸所占的比例约为30．7％0和33．3％。

Soil gas sample at different depths under different plant communities in the sand-fixing vegetation zones were obtained, and then the CO2 concentration in certain soil profiles and the impact of soil tempera- ture and soil moisture on CO2 concentration were analyzed. The results showed that, Soil CO2 concentration under the Caragana korshinskii and Artemisia ordosica communities in the 0--80 cm soil layer increased with depth, the average value was 1 229.3 μmol·mol^-1 and 1 242.7μmol·mol^-1, respectively, which was larger than that in the same depth of mobile sand dunes （978.9μmol·mol^-1 ）. The soil CO2 concentration un- der Artemisia ordosica community was more than the Caragana korshinskii community at 0--40 cm, but the direction was the opposite below 40 cm. Soil moisture and the soil CO2 concentration under different plant communities had consistency in the interannual timescale, soil CO2 concentration under the Artemisia ordosica plant community and the soil moisture content had the more significant relationship than the Cara- gana korshinskii community and sand at 0--40 cm soil depth, but under 40 cm, the order was Caragana korshinskii〉Artemisia ordosica 〉sand. The influence of soil temperature to soil CO2 concentration was generally sand〉Artemisia ordosica〉 Caragana korshinskii, especially in the surface layer, there was a significant correlation under the sand soil profile, and then decreased with soil depth. Soil temperature on soil CO2 concentration under the Caragana korshinskii and Artemisia ordosica communities was more complex, correlation analysis had showed that the correlation was smaller at 0--10 cm, and then rose at 10 --40cm, but began to decrease in the 40--80 cm. In annual time scales, the soil moisture content was the key limiting factor of soil profile CO2 concentrations under different vegetation types, but in the daily time scale, the soil temperature was the main limiting factor. Furthermore, the root respiratory proportion of Caragana korshinskii and Artemisia ordosica communities was approximately 30.7 % and 33.3 %, re- spectively, at 0--80 cm from our study.