基于生态最优理论和基于过程的总初级生产力模型的比较

A Comparative Study of Ecological Optimality Theory-Based and Process-Based Gross Primary Productivity Models

基于植被生态最优理论的P-model,因其输入参数少、结构简单的特点,已成为模拟总初级生产力(Gross Primary Productivity,GPP)的重要模型。同样,基于植被生理生态过程的BEPS(Biosphere-atmosphere Exchange Process Simulator)模型也被广泛应用于GPP的估算。然而,以往的研究缺少对2种模型的比较分析。结合通量塔实测值,对考虑水分限制前后的P-model及BEPS进行模拟,分析和比较二者的模拟差异。结果表明:1)未考虑水分限制的P-model会显著高估GPP,加入水分限制后能够有效减少模拟误差;2)当前P-model使用的水分限制表达式LE/Rn存在校正问题,需要进一步考虑如何在模型中更恰当地表达水分对GPP的限制;3)尽管BEPS整体模拟精度较高,能更准确地反映GPP的季节变化特征,但P-model具有输入参数少、易于实现的显著优点。目前,P-model在水分条件对GPP的限制,以及阴阳叶光利用效率的区分上仍然有较大的改进空间。

The P-model based on the theory of ecological optimization of vegetation has become an important model for simulating gross primary productivity(GPP)due to its few input parameters and simple structure.Similarly,the BEPS(Biosphere-atmosphere Exchange Process Simulator)model,which is based on the physiological and ecological processes of vegetation,has been widely used for the estimation of GPP.However,a comparative analysis study of the two models is lacking in the current study.In this study,we combined the measured values of flux towers with simulations using the P-model before and after considering moisture limitation as well as BEPS,and analyzed and compared the simulation differences between the two.The results show that,1)the P-model without considering moisture limitation significantly overestimates GPP,and the inclusion of moisture limitation can effectively reduce the simulation error.2)The current moisture limitation expression LE/Rn used in the P-model suffers from an over-correction problem,and further consideration needs to be given to how to more appropriately express the limitation of moisture on GPP in the model.3)Although the overall simulation accuracy of BEPS is higher,it can more accurately reflect the seasonal variation characteristics of GPP,P-model has the significant advantages of fewer input parameters and easier implementation.At present,there is still much room for improvement in P-model in terms of the limitation of moisture conditions on GPP and the distinction between light utilization efficiency of sunlit and shaded leaves.