美国黑核桃实生苗生态生理过程对环境因素响应的数值模拟(Ⅲ)：植株冠层光合作用数理模型

Mathematically Modeling of Ecophysiological Process Response to Environmental Factors for American Black Walnut Seedlings(Ⅲ):The Mathematical Models of the Canopy Photosynthesis

以1～2年生北加州黑核桃为试材,建立了具有较高分辨能力的植株群体结构、光分布模型和冠层光合作用模型．将植株冠层按叶面积指数划分为若干层次,上下层之间水平面上太阳辐照度按Monsi&Saekj所提出的指数递减规律分布．冠层内太阳散射光的消光系数由冠层结构决定,而直射光的消光系数则决定于冠层结构与太阳在天空的位置．在同一层次,将叶片的叶倾角划分为6个等级,将叶片的水平位置划分为8个方位．设同一层次中水平面上的太阳辐照度相同,某一方位角和叶倾角的叶面的直接辐射由太阳视运动方程决定．以此为基础,分别计算“光斑区”和“遮荫区”内叶片的光合速率,并通过数值积分计算整个冠层的光合速率及光合日总量．用田间实测资料验证了冠层内太阳辐射分布模型和冠层光合作用模型．敏感性试验分析表明,模型对环境因子和生物学因素有良好的响应．

The mathematical models are set up for the structure, sunlight distribution and photosynthesis in the canopies of hindsi L.＇s seedlings of 1 or 2 years old. The canopies are divided into several layers by unit leaf area index （LAI）. Solar radiation on horizontal plane in every layer is calculated by Monsi-Saeki exponential model. The extinction coefficient for diffused radiation is only given by the canopy architecture. However, the extinction coefficient for direct radiation is decided by both canopy architecture and solar position in the sky. Meanwhile, the leaves in the same layer are divided into 6 ranks in vertical direction and 8 ranks in horizontal direction. The intensities of direct radiation on leaf surface with different orientation and declination are determined by solar orbit equations. On this account, the photosynthetic rates of leaves in irradiated and shaded area are calculated, and the photosynthetic rates and the diurnal total photosynthesis for whole canopy are obtained by integral. The light distribution model and leaf photosynthesis model are validated by the run of it in the field. The models respond well to inputted environmental and biological factors.