退化草地暗沃寒冻雏形土CO_2释放的日变化和季节动态

采用CI-301PS红外CO2分析仪，测定了退化草地暗沃寒冻雏形土CO2排放速率。研究结果表明：（1）CO2排放速率具有明显的日变化，日最大排放速率在12：00～14：00时出现，最低值出现于凌晨4：00～8：00。白天大于夜晚。（2）植物生长季，CO2释放速率有明显的季节变化和物候变化，日平均释放速率为（320.86±130.49）mg/m2·h，CO2释放速率的物候变异为草盛期＞草枯黄期＞草返青期。（3）CO2释放速率的日变化进程主要受气温和地表温度制约，而季节动态与气温及0～30cm地温均呈极显著正相关关系。（4）退化草地上CO2释放速率较低。

DIEL AND SEASONAL CHANGES OF CARBON DIOXIDE EMISSION FROM MOLLIC-CRYIC CAMBISOLS ON DEGRADED GRASSLAND

Diel and seasonal changes of carbon dioxide emission from Mollic-Cryic Cambisols on degraded grassland were studied. The results indicated that: (1) Diel maximum rate of CO2 efflux appeared at 1200～1600 and minimum at 400～800. Rate of CO2 efflux in the daylight was greater than that in the night. (2) There were significant seasonal dynamic and phenophase changes in rate of CO2 emission. Diel average rate of CO2 emission was 320.86±130.49mgm－2h－1. Phenophase variation was exuberance＞withering＞green up. (3) Diel change course of rate of CO2 emission was controlled by air temperature and soil surface temperature. However, the correlations between seasonal dynamic of rate of CO2 emission and air temperature, soil surface temperature, and temperature of each layer of soil (5cm, 10cm, 15cm, 20cm, 30cm) were very significant (P＜0.01). (4) The rate of CO2 emission from Mollic-Cryic Cambisols on the over grazing pasture is lower than that on the moderately grazing pasture.