黄土塬区麦田CO2通量季节变化

利用涡度相关法对黄土塬区小麦地CO2通量季节变化进行了研究。结果表明：（1）小麦CO2通量日变化与生育期、光合有效辐射、土壤温度密切相关。（2）小麦各生育期CO2的平均日收支由大到小依次为拔节孕穗期〉返青期〉起身期〉抽穗期〉成熟期〉灌浆期〉出苗分蘖期〉越冬期。（3）白昼CO2通量与光合有效辐射在出苗分蘖期、起身期、成熟期几乎不相关，在灌浆期低度相关，在其他生育期内都达到了显著相关。CO2通量与夜间2cm土壤温度在越冬、起身、拔节孕穗期显著相关，其他5个生育期内为低度相关。（4）小麦收割后表现为碳源，各天具体状况与前一天是否降雨、当天的天气状况有关。

The seasonal variation of CO2 flux in a wheat field of the Loess Plateau

The seasonal variation of CO2 flux in a winter wheat field of the Loess Plateau was studied using an eddy covariance method. The following results were obtained. (1) Daily CO2 flux was closely related to growing stages, photosynthetically active radiation , and soil temperature. (2) The average daily CO2 flux at different growing stages followed the order of: jointing and booting >reviving >erecting >heading >ripening >grain-filling > seedling and tillering >wintering period. (3) There was little correlation between daytime CO2 flux and photosynthetically active radiation at the seedling-tillering, heading, and maturing stages; but there was weak correlation during grain filling, and strong correlation in the other stages. There was significant correlation between CO2 flux and nighttime soil temperatures at the 2-cm depth at the wintering, heading and jointing and booting stage, and low correlation at the other stages. (4) The wheat field became carbon source after harvest. The carbon budget of a given day was affected by the weather of the day as well as the rainfall condition in the previous day.