半干旱草地净第一性生产力遥感模型研究

Research on a Remote Sensing-based Net Primary Productivity Model for Semi-arid Grasslands

采用MODIS遥感数据,针对内蒙古半干旱草场生态环境特征,以光能利用率模型为基础与生态模型相结合,研究区域尺度下半干旱草地净第一性生产力遥感模型;利用草场植物生长过程中从光合和呼吸作用出发的NPP遥感模型与从植物生物量和衰败量变化出发的GNPP模型的估算值之间构建代价函数,有效地对模型参数进行估算和校正;模型考虑了气温和植物水胁迫的影响,以及时空尺度的差异,并充分利用遥感反演的参数来驱动.模型经内蒙古草场MODIS数据、实测数据、相关模型的验证,结果表明,模型参数校正能提高模型估算的精度,且NPP估算精度满足实际应用需要,此遥感模型合理可行.

This paper presents a regional net primary productivity （NPP） model parameterized with remote sensing information of MODIS, and tests it in areas of Inner Mongolia semi-arid grassland. The model uses the concept of light use efficiency （LUE）, while change of air temperature, plant-water deficits and respiration reduce the efficiency of light usage, and the model is modified to couple with the ecology model to better represent regional environmental characteristics of the semi-arid grasslands. In this study, the two different ways to simulate NPP in the process of vegetation growth were introduced to calibrate model parameters. The accuracy of model products was assessed by comparing them with field measurement and other models. The simulated NPP has good linear relation with the measured （R^2 = 0.948）. The promising results suggest this model could describe spatial and temporal distribution of net primary productivity for semi-arid grassland management.