中国北方针叶林生长季碳交换及其调控机制

采用开路式涡动相关法对北方针叶林连续2个生长季节(2007和2008年)的碳交换及其影响因素进行分析.结果表明：北方针叶林生态系统总生产力(GEP)、生态系统呼吸(R_e)和净生态系统碳交换(NEE)在6月下旬到8月中旬的生长旺盛期达到最大值，但各峰值出现的日期并不一致.2007和2008年北方针叶林生长季的日均GEP、日均R_e、日均NEE分别为19.45、15.15、-1.45 g CO₂·m^-2·d^-1和17.67、14.11、-1.37 g CO₂·m^-2·d^-1，2007年碳交换明显大于2008年，这可能是生长季较高的平均温度及光合有效辐射引起(2007年为12.46 ℃和697 μmol·m^-2·s^-1，2008年为11,04 ℃和639 μmol·m^-2·s^-1).北方针叶林的GEP与温度和光合有效辐射具有很好的相关性，其中与气温的相关系数接近0.55(P<0.01)；R_e主要受温度调控，相关系数为0.66～0.72(P<0,01)；NEE与光合有效辐射相关性最大，相关系数为0.59～0.63 (P<0.01).

Carbon exchange of Chinese boreal forest during its growth season and related regulation mechanisms

Based on the two-year continuous observation on the carbon exchange of Chinese boreal forest during its growth seasons in 2007 and 2008 by the methodof open path eddy covariance, this paper analyzed the seasonal dynamics of the gross ecosystem productivity (GEP), ecosystem respiration (R_e), and net ecosystem carbon exchange (NEE) of the forest, with related regulation mechanisms approached. The GEP, R_e, and NEEof the forest reached to their maximum in the vigorous growth period from late June to mid August, but the dates of the maximum appeared differed. The mean daily GEP, R_e, and NEE were 19.45, 15.15, and -1.45 g CO₂·m^-2·d^-1 in 2007, and 17.67, 14.11, and -1.37 g CO₂·m^-2·d^-1in 2008, respectively. The intensity of the carbon exchange during growth season was obviouslystronger in 2007 than in 2008, possibly due to the higher mean air temperature (12.46 ℃ in 2007 vs. 11.04 ℃ in 2008) and the higher mean photosynthetically active radiation (PAR) (697 μmol·m^-2·s^-1 in 2007 vs. 639 μmol·m^-2·s^-1 in 2008). The GEP had close linear relationships with air temperature and PAR, and the correlation coefficient of GEP and air temperature was around 0.55(P<0.01). The R_e was mainly controlled by air temperature, with the correlation coefficient being 0.66-0.72 (P<0.01), and the NEE was mainly controlled by PAR, with the correlation coefficient being 0.59-0.63 (P<0.01).