基于改进的CASA模型模拟草原综合顺序分类体系各类的最大光能利用率

Use improved CASA model to estimate the maximum light use efficiency of of class in grassland comprehensive and sequential classification system

植被最大光能利用率是净初级生产力(NPP)估算的一个重要参数,对它的大小一直存在争议。利用遥感数据、气象数据和中国区域NPP实测资料,依据基于草原综合顺序分类(CSCS)改进的CASA模型,采用改进的最小二乘法对中国41类草地的最大光能利用率(εmax)进行了模拟,并通过与他人估算的光能利用率(ε)进行比较来验证εmax的可靠性和准确性。结果表明:此次研究的ε值略高于其他的研究结果。其主要原因有:ε最大值和最小值之间的跨度较大,从而使得平均值较高;由于缺乏实测数据,个别草地类型的ε估算值较高,导致了本研究ε值偏高;各研究采用的分类体系不同,模型和数据来源不同,从而导致结果存在差异。本研究中的εmax根据实测数据模拟得到,今后需进一步收集实测数据,对参数εmax的合理取值进行调整。

The maximum light-use efficiency（ max）is one of the most important factors for vegetation net primary production,but its value has been controversial. In this study,least square method was used to estimate the max values of 41 grassland classes by Comprehensive and Sequential Classification System（CSCS）in China with the improved Carnegie-Ames-Stanford Approach（CASA）model,and then these values were compared with the results estimated by other researchers. The results showed that the max values in the study were higher than the other results. The reason for this may be that mum value was high,resulting in the average of was land classes was high owning to the absence of field hig ob （1） h,（2 the span between the maximum value and the mini ） the estimation value of max of some certain grass served data, or （3） the classification system, models, and data sources in different studies were different. Thus, further research should be done to investigate the most suitable max values using more field observed data.