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Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem

机译:陆地生态系统冠层尺度的光合蒸腾耦合模型

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At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO_2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R~2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO_2 m~(-2) s~(-1); the slope, R~2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60 mmol H_2O m~(-2) s~(-1), respectively (n = 752). The relationship between canopy photosynthesis, transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum.
机译:以大叶为假说,建立了由单叶到冠层的比例缩放SMPT-SB模型,建立了一个生态系统的光合-蒸腾耦合循环模型,并讨论了模型参数化方法。通过模拟冠层光的分布,可以利用单个内部电导率与光合光子通量密度之间的关系将冠层内部的电导率积分到冠层,从而将冠层内部对CO_2的电导率从单个叶片缩放到整个冠层。利用ChinaFLUX的长白山地区通过涡度协方差法观测的数据,检验了该模型在冠层尺度上的应用。在无水胁迫下,模拟的生态系统净光合速率与实测数据拟合得很好,实测值和模拟值的线性回归方程的斜率和R〜2分别为0.7977和0.8892(n = 752),且平均值绝对误差为3.78μmolCO_2 m〜(-2)s〜(-1);蒸腾速率的斜率,R〜2和平均绝对误差分别为0.7314、0.4355和1.60 mmol H_2O m〜(-2)s〜(-1)(n = 752)。通过对冠层整体进行处理,忽略冠层内部的综合反馈机制,讨论了冠层光合作用,蒸腾作用与外界环境条件之间的关系,并指出降水过程严重影响了蒸腾速率的模拟。与基于生态生理过程的模型相比,SMPT-SB模型简单易用。可作为土壤-植物-大气连续体的基本碳水耦合模型。

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