中文摘要：

采用涡动相关法对青藏高原唐古拉地区高寒草甸生态系统在2007年CO2通量及活动层水热动态进行了连续观测。结果表明,各月CO2通量日变化均呈单峰型,日通量峰值一般出现在中午,最大排放峰值出现在5月,为0.29 g·m-2·h-1;最大吸收峰值出现在8月,为-0.25 g·m-2·h-1,除7月和8月CO2通量日变化表现出吸收特征外,其余各月均表现为排放特征。与青藏高原连续多年冻土周边地区相比,唐古拉地区CO2通量日变化峰值明显偏小。CO2通量季节变化呈双峰型,表现为春、秋季强排放、夏季弱吸收和冬季弱排放。5月为CO2通量全年最大排放月,排放量为132.4 g·m-2;8月为CO2通量全年最大吸收月,吸收量为-37.7 g·m-2。春、秋季,CO2通量与5 cm土壤温度和未冻水含量变化呈显著的正相关关系,而夏季与5 cm土壤温度变化呈显著的负相关关系,CO2通量对光合有效辐射变化基本没有响应。

英文摘要：

Diurnal and seasonal variations of CO2 flux was measured with a open-path eddy covariance system for Tanggula apline meadow ecosystem in 2007 in order to assess carbon for apline meadow ecosystems in the Qinghai-Xizang Plateau.The results showed that the CO2 flux was distinct in the processes of daily and seasonal changes.During the freezing season,from September to June,CO2 flux showed small fluctuation with the largest net CO2 flux of 0.29 g m-2 h-1 in May.The diurnal CO2 flux was close to zero during most time of the day,but it showed a small net CO2 flux from 11：00 to 20：00.The thawing season,from July to August,the system exhibited net CO2 peak value from 11：00 to 20：00,but the net CO2 emission is from 20：00 to 11：00.Maximum CO2 peak value appeared from 12：00 to 14：00.The CO2 flux also had obviously seasonal variation.Remarkable peak value occurred in March,and relatively big release happed in May and September.The maximum daily net CO2 flux appeared in July and August,and CO2 flux was close to zero during winter.CO2 flux showed a linearily increase relations with 5 cm depth soil temperature and soil moisture content during spring and autumn,and a linearily regression relation appeared during summer.