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水蚀风蚀交错带是黄土高原土壤侵蚀最严重地区,该地区立地条件复杂,土壤质地有较大的空间变异性,对生态系统碳循环过程产生重要影响。该文选取土壤质地为立地条件的主要参考因子,利用便携式CO2分析仪对黄土高原水蚀风蚀交错带不同立地条件下2种典型灌木(柠条和沙柳)土壤呼吸特征进行了连续2a的野外对比研究,分析不同立地条件下灌木林地土壤呼吸之间的差异,阐明土壤呼吸的动态变化及其对土壤温度的敏感性。结果表明:在不同立地条件下,柠条林地黄绵土土壤呼吸高于风沙土,相反,沙柳林地风沙土土壤呼吸高于黄绵土。每种灌木林地在不同立地条件下土壤呼吸呈现明显的季节性变化,土壤呼吸速率的高峰值出现在7、8月份。不同立地条件下土壤呼吸与土壤温度呈现显著指数函数关系,每种灌木林地黄绵土土壤呼吸的温度敏感性系数Q10高于风沙土,从而对土壤温度的响应更为敏感。
The water erosion and wind erosion ecotone is the most serious area of soil erosion in the Loess Plateau. The site conditions are complex and the soil texture has great spatial variability, which has an important impact on the ecosystem carbon cycle. In this paper, soil texture was chosen as the main reference condition for soil conditions. The soil CO2 respiration characteristics of two typical shrubs (Caragana korshinskii and Salix psammophila L.) were studied in a field experiment under different field conditions in a cross-ecotone between water and wind erosion in the Loess Plateau. The differences of soil respiration of shrub land under different site conditions were analyzed to clarify the dynamic changes of soil respiration and their sensitivity to soil temperature. The results showed that under different site conditions, soil respiration of loessial soil in Caragana korshinskii woodland was higher than that of aeolian sandy soil. On the contrary, the soil respiration of sandy aera in sandy forest was higher than that of loess soil. Soil respiration of each shrub land under different site conditions showed obvious seasonal changes. The peak of soil respiration rate appeared in July and August. The soil respiration and soil temperature showed a significant exponential function under different habitats. The temperature sensitivity coefficient of soil respiration of loessial soil in each shrub land was higher than that of aeolian sandy soil, and was more sensitive to soil temperature.