基于涡度相关技术的农田生态系统碳收支评估

Evaluation of carbon budget for farmland ecosystem based on the eddy correlation technology

以涡度相关技术为主要观测手段,连续观测冬小麦和水稻生态系统主要生长季净生态系统CO_(2)交换(NEE)的变化规律,评估两种农田生态系统CO_(2)的源/汇功能.结果表明,整个观测期间,两种作物生态系统CO_(2)浓度的日变化曲线呈现白天低、晚上高的“一峰一谷”型,冬小麦生态系统变化较为平缓,而水稻生态系统变化则比较剧烈.冬小麦和水稻生态系统白天30 minCO_(2)通量的平均值分别为-13.4μmol·m^(-2)·s^(-1)和-12.9μmol·m^(-2)·s^(-1),通量最高值分别出现冬小麦的孕穗期与水稻的开花期.此外,两种作物生长季CO_(2)通量表现出“U”形曲线的日变化特点,白天以吸收CO_(2)为主,冬小麦和水稻生态系统分别于12:00和11:30达到吸收峰值;夜间CO_(2)通量变化较为稳定,表现为呼吸排放CO_(2).两种农田生态系统均表现为碳汇,冬小麦与水稻生态系统净碳交换分别为188.2g·m^(-2)与233.8g·m^(-2).

This study used eddy correlation technology to continuously observe the changes of net ecosystem CO_(2)exchange(NEE)during the main growing seasons of winter wheat and rice ecosystems,and evaluated the CO_(2)source/sink functions of the two farmland ecosystems.The results showed that:During the whole observation period,the diurnal variation curves of CO_(2)concentration for the two crops showed typical one⁃peak⁃one valley pattern,which was low during the day and high during the night.The diurnal variation curves of CO_(2)concentration for winter wheat was relatively flat,while that of rice is more severe.The mean values of 30⁃minute CO_(2)fluxes during the daytime for winter wheat and rice were-13.4μmol·m^(-2)·s^(-1)and-12.9μmol·m^(-2)·s^(-1),respectively.The highest fluxes occurred at the booting stage of winter wheat and the flowering stage of rice.In addition,CO_(2)fluxes of the two crops during the growing season showed a diurnal variation characteristic of a U⁃shaped curve.Two farmland ecosystems mainly absorbed CO_(2)during the daytime,and the absorption peaks of winter wheat and rice appeared at 12:00 and 11:30,respectively.The CO_(2)flux changes during the night were relatively stable,which manifested as the emissions of CO_(2)respiratory.Two farmland ecosystems were carbon sinks,and the net ecosystem carbon exchange were 188.2 g·m^(-2)for winter wheat and 233.8 g·m^(-2)for rice.