Abstract:

Based on the continuous observation data of carbon dioxide flux using eddy covariance technique (ECT) at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during 2007-2012, and combined meteorological observations, the variation characteristics of net ecosystem carbon exchange (NEE) and environment factors influencing NEE there were analyzed. Results are as follows:(1)The annual cumulative average NEE value at SACOL was -214.50±43 gC/m², thereinto, -171.58±41 gC/m² during growing season, and -42.92±5 gC/m² during non-growing season. (2)The diurnal variation curve of NEE at SACOL presented an asymmetrical U shape, and net radiation was the main influencing factor. The SACOL was an obvious sink of carbon with daily average NEE value of -1.15 gC/m² . (3)The variation of carbon dioxide flux showed significant seasonal and interannual differences. The amplitude of variation was bigger in growing season, which was affected by soil conditions.

Key words: Key words: semi-arid Loess Plateau, net ecosystem carbon exchange, net radiation, soil moisture

摘要：

利用涡动相关技术对黄土高原半干旱区SACOL站2007~2012年连续6 a的CO2通量进行观测，并结合气象观测数据，分析兰州大学半干旱气候与环境观测站（SACOL站）净生态系统碳交换量（NEE）的变化特征以及环境影响因子。结果表明：（1）黄土高原半干旱区SACOL站NEE年累积平均值为-214.50±43 gC/m² ，其中生长季节累积平均值为-171.58±41 gC/m² ，非生长季节累积平均值为-42.92±5 g C/m² ；（2）SACOL站NEE的日变化呈“U”型，净辐射是影响NEE日变化的主要因子。NEE日平均值为-1.15 gC/m²，表现为明显的CO2吸收，即黄土高原半干旱区是重要的碳汇区；（3）NEE值有明显的年际差异和季节变化特征，生长季节比非生长季节变化幅度大；NEE在生长季节主要受到土壤湿度的影响，而土壤温度会影响非生长季节NEE的变化。

关键词: 黄土高原半干旱区, 净生态系统碳交换, 净辐射, 土壤湿度