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2011年11月—2012年10月,采用涡度相关法对北京市八达岭林场4年生针阔混交人工林的碳交换特征进行了连续观测.结果表明:观测期间,该森林生态系统在7、8月为碳汇,其余月份均为碳源,净碳释放量与吸收量分别在4月和7月达到最大.生态系统净生产力为(-256±21)g C·m-2·a-1,其中生态系统呼吸为(950±36)g C·m-2·a-1,总初级生产力为(694±17)g C·m-2·a-1.生态系统呼吸与10 cm深度土壤温度呈较好的指数关系,其温度敏感性系数(Q10)为2.2.在5—9月,白天生态系统净碳交换对光合有效辐射的响应符合直角双曲线方程,表观量子效率呈明显的季节变化(0.0219~0.0506μmol CO2·μmol-1),生态系统最大光合速率和白天平均生态系统呼吸强度与光合有效辐射和温度的季节变化趋势相似.此外,7、8月饱和水汽压差与土壤含水量对白天生态系统净碳交换有显著的影响.
From November 2011 to October 2012, the carbon exchange characteristics of 4-year-old coniferous and broad-leaved plantation mixed forest in Badaling Forest Farm in Beijing were observed continuously by using the eddy covariance method.The results showed that during the observation period, The monthly carbon sequestration, the rest of the month as a carbon source, net carbon emissions and absorption reached the maximum in April and July respectively.The net ecosystem productivity was (-256 ± 21) g C · m-2 · a-1 (950 ± 36) g C · m-2 · a-1 and total primary productivity (694 ± 17) g C · m-2 · a-1, respectively. Ecosystem respiration and soil depth of 10 cm The temperature had a good exponential relationship and the temperature sensitivity coefficient (Q10) was 2.2. From May to September, the response of net carbon exchange to photosynthetically active radiation in daytime was in accordance with the rectangular hyperbolic equation, and the apparent quantum yield was significant The seasonal variation (0.0219 ~ 0.0506μmol CO 2 · μmol-1), the maximum photosynthetic rate of the ecosystem and the mean daily respiratory intensity of the ecosystem were similar to those of photosynthetically active radiation and temperature. In addition, Water content has a significant effect on net carbon exchange during the daytime.