为定量分析植物冠层结构与光分布及光合作用之间的关系,模拟实际环境中植物冠层的实时光合速率,为诸如作物模型中产量估测提供一种植物冠层尺度光合生产力计算方法,本文构建了基于L-系统的3D虚拟植物冠层光合作用模拟模型。模型主要分为...为定量分析植物冠层结构与光分布及光合作用之间的关系,模拟实际环境中植物冠层的实时光合速率,为诸如作物模型中产量估测提供一种植物冠层尺度光合生产力计算方法,本文构建了基于L-系统的3D虚拟植物冠层光合作用模拟模型。模型主要分为3部分:基于L-迭代文法系统与三维图形绘制技术构建3D虚拟植物冠层结构,利用正向光线跟踪及天空可见率算法模拟虚拟冠层内光辐射(Photosynthetically active radiation,PAR)传输,基于太阳几何参数、大气影响参数及地理位置等参数计算真实环境中虚拟冠层顶部实时PAR强度。利用此模型,直接输入或插值处理光合环境因子数值,采用单叶光合作用模型和相关呼吸作用模型,可计算冠层内净光合作用速率并进行周期内植物体生物量的积累估算。以实测的幼龄杉木为模拟对象,计算其冠层内净光合作用速率及周期内生物量积累,模拟结果表明,基于虚拟冠层的PAR分布模拟及其冠层光合作用速率计算,是一种对植株光合生产力估算的有效方法。展开更多
Transpiration and photosynthesis are two closely related and intercoupled processes that dominate the physiological activities and yield of crops. Therefore, there is a need to study water-carbon coupling modeling at ...Transpiration and photosynthesis are two closely related and intercoupled processes that dominate the physiological activities and yield of crops. Therefore, there is a need to study water-carbon coupling modeling at various scales to increase water use efficiency (WUE). Using a summer maize field in North China as an example, the variations in leaf and canopy photosynthesis and transpiration (or evapotranspiration) were analyzed. The synthetic model of photosynthesis-transpiration based on stomatal behavior (SMPT-SB) was then calibrated and validated at the two scales. The leaf photosynthesis and transpiration, as well as the canopy photosynthesis and evapotranspiration, have a consistent diurnal trend. However, the canopy evapotranspiration is affected more by topsoil moisture content. The regression coefficient between leaf photosynthesis, transpiration, and WUE estimated by the SMPT-SB and the measured values was found to approach 1, with a coefficient of determination of more than 0.74. The relative error between the two sets of values is less than 11%. Therefore, the SMPT-SB could express fairly well leaf photosynthesis, transpiration, and WUE. The estimated canopy-scale photosynthesis by the SMPT-SB is also in good agreement with the measured values. However, this model underestimates the canopy evapotranspiration when the topsoil has high moisture content and therefore overestimates, to a certain extent, the canopy WUE.展开更多
文摘为定量分析植物冠层结构与光分布及光合作用之间的关系,模拟实际环境中植物冠层的实时光合速率,为诸如作物模型中产量估测提供一种植物冠层尺度光合生产力计算方法,本文构建了基于L-系统的3D虚拟植物冠层光合作用模拟模型。模型主要分为3部分:基于L-迭代文法系统与三维图形绘制技术构建3D虚拟植物冠层结构,利用正向光线跟踪及天空可见率算法模拟虚拟冠层内光辐射(Photosynthetically active radiation,PAR)传输,基于太阳几何参数、大气影响参数及地理位置等参数计算真实环境中虚拟冠层顶部实时PAR强度。利用此模型,直接输入或插值处理光合环境因子数值,采用单叶光合作用模型和相关呼吸作用模型,可计算冠层内净光合作用速率并进行周期内植物体生物量的积累估算。以实测的幼龄杉木为模拟对象,计算其冠层内净光合作用速率及周期内生物量积累,模拟结果表明,基于虚拟冠层的PAR分布模拟及其冠层光合作用速率计算,是一种对植株光合生产力估算的有效方法。
基金supported by the National Natural Science Foundation of China (51009151,51109225 and 91125017)the National Basic Research Program of China (2006CB403405)the Special Scientific Fund sponsored by IWHR for Department of Irrigation and Drainage (1209)
文摘Transpiration and photosynthesis are two closely related and intercoupled processes that dominate the physiological activities and yield of crops. Therefore, there is a need to study water-carbon coupling modeling at various scales to increase water use efficiency (WUE). Using a summer maize field in North China as an example, the variations in leaf and canopy photosynthesis and transpiration (or evapotranspiration) were analyzed. The synthetic model of photosynthesis-transpiration based on stomatal behavior (SMPT-SB) was then calibrated and validated at the two scales. The leaf photosynthesis and transpiration, as well as the canopy photosynthesis and evapotranspiration, have a consistent diurnal trend. However, the canopy evapotranspiration is affected more by topsoil moisture content. The regression coefficient between leaf photosynthesis, transpiration, and WUE estimated by the SMPT-SB and the measured values was found to approach 1, with a coefficient of determination of more than 0.74. The relative error between the two sets of values is less than 11%. Therefore, the SMPT-SB could express fairly well leaf photosynthesis, transpiration, and WUE. The estimated canopy-scale photosynthesis by the SMPT-SB is also in good agreement with the measured values. However, this model underestimates the canopy evapotranspiration when the topsoil has high moisture content and therefore overestimates, to a certain extent, the canopy WUE.
