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生态系统光能利用率(LUE)反映了植被通过光合作用利用光能吸收和固定大气中CO2的能力,是表征生态系统生产力的重要指标。选取长白山温带阔叶红松(Pinus koraiensis)林生态系统为研究对象,利用涡度相关通量观测数据,采用直角双曲线方程获取了生态系统光合作用的表观量子效率(ε);基于总生态系统初级生产力(GEP)与下垫面入射光合有效辐射(Q)的比值得到生态光能利用率(LUEeco)。研究表明:在季节尺度上,ε与LUEeco均表现出显著的单峰变化特征,并主要受到土壤温度和归一化植被指数(NDVI)的调控,同时,ε和LUEeco都受到GEP的显著影响,而与Q的相关性较弱或无显著相关关系,但散射辐射的增加在一定程度上有助于提高生态系统的LUE。ε与LUEeco存在显著的线性正相关关系,但ε明显高于LUEeco。2003–2005年,ε与LUEeco每年最大值的平均值分别为(0.087±0.003)和(0.040±0.002)μmol CO2·μmol photon–1,年际间变异度分别为4.17%和4.25%,而不同年份之间最大差异均达到8%或8%以上,从而对模型模拟结果产生明显影响。因此,在基于光能利用率模型的模拟研究中,最大LUE的年际变异需要在参数反演和优化中给予重要考虑。
Ecosystem utilization of light (LUE) reflects the ability of vegetation to absorb and fix atmospheric CO2 through photosynthesis, which is an important indicator of ecosystem productivity. Taking Pinus koraiensis forest ecosystem of Changbai Mountain as the research object, the apparent quantum yield (ε) of photosynthesis of the ecosystem was obtained by using the rectangular hyperbolic equation by using the eddy covariance observation data. The ratio of productivity (GEP) to incident solar radiation (Q) on the underlying surface yields the LUEeco. The results showed that both ε and LUEeco showed significant unimodal variation on the seasonal scale and were mainly controlled by soil temperature and normalized vegetation index (NDVI). Both ε and LUEeco were significantly affected by GEP, However, the correlation with Q is weak or no significant correlation, but the increase of scattered radiation contributes to some extent to improve the LUE of the ecosystem. There is a significant linear positive correlation between ε and LUEeco, but ε is significantly higher than that of LUEeco. From 2003 to 2005, the annual maximum values of ε and LUEeco were (0.087 ± 0.003) and (0.040 ± 0.002) μmol CO2 · μmol photon-1, respectively, with annual variations of 4.17% and 4.25% The biggest difference between the years reached 8% or more than 8%, which has a significant impact on the model simulation results. Therefore, in the simulation study based on the model of light energy utilization, the interannual variation of the maximum LUE needs to be given important consideration in parameter inversion and optimization.