BEPS模型在华北平原冬小麦估产中的应用

粮食是一切生产和生活的根本，准确地估计冬小麦的产量，对国家制定粮食政策至关重要。该文利用北部生态系统生产力模拟（BEPS，boreal ecosystem productivity simulator）模型能够模拟森林植被净第一性生产力的特点，分析了BEPS模型在冬小麦估产中的适用性和局限性。针对冬小麦和森林植被冠层的不同生长特点，假设冬小麦冠层具有水平均一、垂直分层的结构，利用辐射传输方程，将原BEPS模型中的两片大叶模型改造为多层-两片大叶模型；同时，利用前人提出的收获指数（HI，harvest index）的概念，将冬小麦的净第一性生产力转化为经济产量，从而实现利用遥感机理模型对冬小麦产量的估算。将改进后的模型用于华北平原冬小麦估产中，并利用国家级农业气象站点的实测产量资料对模拟结果进行验证，复相关系数达到0.817，说明改进后的BEPS模型可以用于华北平原冬小麦的估产研究。

Application of BEPS model in estimating winter wheat yield in North China Plain

Food is the foundation for any production and subsistence. It is important for making national grain policy to estimate yield of winter wheat accurately. In this paper, with the character of BEPS (boreal ecosystem productivity simulator) in simulating vegetation net primary productivity, its applicability and limitation were analyzed in estimating yield of winter wheat. According to the characteristics of winter wheat and forest canopy, a hypothesis about horizontal homogeneous, vertical layered was made. Based on the radiative transfer equation, two-big-leaf model in BEPS model is modified into multilayer-two-big-leaf model. Meanwhile, net primary productivity of winter wheat was converted into yield using harvest index. So the modified BEPS was applied to estimate yield of winter wheat in North China Plain. The simulated yield agrees well with observations from agro-meteorological stations and the R2 reaches to 0.817. This study demonstrates that modified BEPS can be used to estimate yield of winter wheat in North China Plain if remotely sensed imageries are available.