黑河流域山区牧坡草地土壤呼吸的时间变化及水热因子影响

采用LI6400-09土壤呼吸室和LI-6400便携式光合作用测量系统，在生长季节对黑河流域山区牧坡草地土壤呼吸速率进行了连续观测，研究不同环境条件下土壤CO2释放速率及其对气候和土地利用变化的反馈作用.结果表明,牧坡草地土壤呼吸速率的日变化规律为夜间土壤呼吸速率较低，最低值在5～10月份，分别出现在7:00、6:30、5:30、5:00、6:00和 7:00，此后开始升高，达到最大值的时间分别为15:00、14:30、14:30、13:30、14:00和15:00，在16:00～18:30又逐渐下降，整个过程呈单峰曲线；土壤呼吸速率日均值介于0.31～6.98 μmol·m^-2·s^-1.土壤呼吸速率7、8月份最高，5月与9月份次之，4月与10月份基本一致，整个过程的变化趋势呈单峰曲线形式.土壤呼吸速率与温度呈显著指数关系，与土壤含水量呈显著乘幂关系.

Temporal variation of soil respiration on sloping pasture of Heihe River basin and effects of temperature and soil moisture on it

Employing LiCor 6400 gas exchange analyzer and soil respiration chamber attachment (LiCor Inc., Lincoln, NE, USA), this paper continuously measured the soil surface CO2 effluxes on the sloping pasture of Heihe River basin from early April to late October 2003 to investigate the soil CO2 efflux rate and its feedback to the changes of climate and land use. The results showed that from May to October, the diurnal variation of soil respiration was low at night, the lowest at 7:00, 6:30, 5:30, 6:00 and 7:00, raised rapidly at 7:00 - 8:30, and then descended at 16:00 - 18:30. The maximum soil CO2 efflux appeared at 15:00, 14:30, 14:30, 13:30, 14:00 and 15:00. The mean daily soil respiration rate was 0.31 - 6.98 micromol m(-2) s(-1), with the maximum in July and August, the second in May and September, and nearly consistent in April and October. Soil respiration rate had an exponential and power correlation with temperature and soil moisture, respectively.