北亚热带次生栎林生态系统非生长季CO_2通量特征

CO_2 Flux Characteristics of an Secondary Oak Forest Ecosystem in Non-growing Seasons in Northern Subtropics,China

森林与大气之间CO2通量的观测有助于理解森林生态系统的碳循环及其控制机理,研究非生长季森林与大气间的CO2通量特征,对准确地估算森林生态系统CO2平衡具有重要的意义。以北亚热带次生栎林生态系统为研究对象,采用开路式涡度相关技术,于2011年12月1日至2012年2月29日对其CO2通量特征和环境因子进行连续观测。结果表明:非生长季该生态系统CO2通量具有较明显的日际变化特征,在白天表现为碳吸收,CO2通量在12:30—13:30达到吸收峰值,夜间表现为碳释放,昼夜通量变动范围为-0.37～0.23 mg.m-2.s-1;日平均气温维持在-3.36～11.67℃时,光合有效辐射与该生态系统CO2通量呈直线相关;5 cm处土壤温度与夜间CO2通量呈指数相关,但与土壤含水率之间相关性并不明显。

CO2 flux between the forest and the atmosphere is useful for the research on carbon cycle in forest ecosystem and its controlling mechanism.It is important to accurately estimate forest system CO2 balance for the CO2 flux characteristic between the forest and the atmosphere in non-growing season.We chose the secondary oak forest ecosystem as the sample site in non-growing season in northern subtropics areas,and measured the forest ecosystem CO2 flux and environmental factors by the open-path eddy covariance system from December 1,2011 to February 29,2012.The ecosystem CO2 flux changes obviously at the scale of day.It assimilates CO2 in daytime and releases CO2 in night and reaches the uptake peak during 12：30 and 13：30.The CO2 flux ranges from-0.37 to 0.23 mg·m-2·s-1 during the day.When the average daily temperature maintains between-3.36 ℃ and 11.67 ℃,it shows the linear correlation between the photosynthetically active radiation and the CO2 flux.The soil temperature in 5 cm depth and the night CO2 flux have the relationship of exponential correlation,but the correlation is not significant between the CO2 flux and the soil moisture.