川西亚高山针叶林土壤呼吸速率与不同土层温度的关系

采用密闭气室红外CO2分析法（IRGA），在野外连续定位测定了川西亚高山冷杉原始林的土壤呼吸，并对其不同土层（0、5、10、15和20cm）的温度进行了同步测定．在此基础上，分析了土壤呼吸的日、季节动态变化，及其与不同土层温度的关系和土壤呼吸Q10值变化．结果表明：冷杉原始林土壤呼吸呈现明显的日变化和季节变化．土壤呼吸的日最高值出现在12：00-14：00，最低值出现在8：00—10：00，与土壤表面温度的日变化一致；土壤呼吸的季节变化表明：7—8月的土壤呼吸高于9-11月，与不同土层温度季节变化规律一致；土壤呼吸与不同土层温度呈显著的指数增长关系，土壤呼吸速率与土壤15cm深处温度的相关性明显高于其它土层；利用Q10模型计算0～20cm各土层的Q10值分别为2．36、4．75、4．90、6．27和5．46，表明海拔高、温度低的环境条件下，土壤呼吸的Q10值偏高．

The relationship between soil respiration and the temperature at different soil depths in subalpine coniferous forest of western Sichuan Province

By using closed chamber IRGA technique, a continuous measurement of soil respiration rate was conducted in the subalpine natural coniferous forest mainly composed of Abies faxoniana in the eastern edge of Qinghai-Tibet Plateau, with the temperature at different soil depths (0, 5, 10, 15 and 20 cm) measured simultaneously. Base on the measurements, the quantitative relationships between soil respiration rate and the temperature at different soil depths were explored, and the results showed that the soil respiration rate in the forest had remarkable diurnal and seasonal changes, being the highest at 12:00-14:00 and in August, and the lowest at 8:00-10:00 and in November, which were accorded with the dynamics of soil temperature. Soil respiration rate had a significant exponential correlation with the temperature at different soil depths, and the highest correlation occurred at the soil depth of 15 cm (R2=0.82, P<0.01). The Q10 value at soil depths of 0, 5, 10, 15 and 20 cm was 2.36, 4.75, 4.90, 6.27 and 5.46, respectively, indicating that the Q10 value of soil respiration tended to be larger at high elevation with low temperature.