青海湖高寒湿地生态系统夏季CO2通量日变化及其影响因子研究

利用涡度相关技术对青海湖高寒湿地生态系统夏季CO２通量日变化特征进行分析，并且结合气象观测数据对CO２通量日变化的影响因子进行探讨。结果表明，青海湖高寒湿地生态系统夏季CO２通量日变化呈“U”字型，白天8：00—20：00 CO２通量值为负，其他时间为正，最低值出现在12：30，为-15.34 μmol·m-2·s-1。CO２通量日平均值为-3.65 μmol·m-2·s-1（约-13.87 g·m-2·d-1），表现为明显的CO２吸收，是重要的碳汇。CO２通量与净辐射、气温和表层土壤温度的相关性分析表明，净辐射是影响青海湖高寒湿地生态系统夏季CO２通量日变化的主要因子，气温次之，表层土壤温度对CO２通量的影响最小。采用多元回归分析得出CO２通量与各个影响因子之间的关系符合三元一次线性回归方程，R2=0.689，且达到极显著水平（P〈0.01）。

Diurnal Variation of CO2 Flux from Qinghai Lake Alpine Wetland Ecosystems in Summer and Its Affecting Factors

Diurnal variation of CO2 flux from the Qinghai Lake alpine wetland ecosystem in summer was analyzed with the continuous eddy covariance technology,and factors affecting the variation were explored by taking into account meteorological observation data. Results show that： the CO2 flux from the Qinghai Lake alpine wetland ecosystem varied in a U shape during a day in summer. During the time period from 8：00-20：00, CO2 flux lingered below zero and during the remaining time period, it stayed above zero. Its lowest value appeared at 12：30, being -15.34μmol·m-2·s-1 and its daily mean value was -3.65μmol·m-2·s-1 （about-13.87 g·m-2·d-1）, which indicates that the ecosystem is apparently an important carbon sink, absorbing CO2. Correlation analysis of CO2 flux with net radiation, air temperature and surface soil temperature shows that net radiation is the main factor affecting diurnal variation of CO2 flux from the ecosystem in summer, and followed by air temperature and soil temperature. Multivariate regression analysis shows that the relationships of CO2 flux with its affecting factors fit with the multiple linear regression equation, R2=0.689,and even reach a significant level（P〈0.01）.