松嫩平原西部草地净初级生产力遥感估算与验证

Remote-sensing Estimation and Validation of Grassland Net Primary Productivity of Western Songnen Plain in Northeast China

在CASA模型基础上,根据松嫩平原西部自身特点对模型参数获取方法进行改进。以MODIS NDVI数据和气象数据为主要数据源,估算2000～2009年松嫩平原西部草地净初级生产力,并通过多种方法对估算结果进行精度验证。结果表明:利用气候经验模型估算的太阳总辐射及改进后的水分胁迫因子计算结果精度较高,所作改进在保留原始CASA模型生理生态学基础上简化了模型输入参数,对本研究区是可行的。通过与实测数据(实测值与估算值之间R2=0.64,P<0.05)、通量观测数据(估算精度为72%;相关系数R=0.9,P<0.05)、MODIS NPP产品(总体精度为81.41%)及他人估算结果对比发现,本研究估算的松嫩西部草地NPP结果精度较高。2000～2009年松嫩平原西部草地年NPP总量介于8.46～11.22Tg C之间,平均值为9.92Tg C。空间上,各年NPP均呈南低北高的分布格局;受气候因素和土壤条件影响,松嫩平原西部黑龙江省部分的草地NPP高于吉林省部分。过去10年间,松嫩西部草地NPP按降序排列依次为:2008>2005>2002>2007>2003>2004>2006>2009>2000>2001。

Based on the CASA model, the improvements for parameters have been made according to the characteristics of wetstern Songnen Plain in northeast China. Taking the MODIS NDVI and meteorological data as the main inputs, grassland net primary productivity （NPP） of western Songnen Plain was estimated from 2000 to 2009, and for validation, several methods were taken. The results showed that the accuracy of grassland NPP estimated by the improved model was relatively high. The improvements not only kept physiological and ecological basis of the original CASA model, but also simplified the parame- ters, so the improved model was feasible for wetstern Songnen Plain. Through comparison with observed NPP （R2=0.64,P〈0.05）, eddy observation data （accuracy was 72%; correlation coefficients was 0.9, P（0.05）, MODIS NPP （accuracy was 81.41%） and others research results, it was found that the esti- mated grassland NPP was reliable. Total NPP of grassland in western Songnen Plain was between 8.46 and 11.22 Tg C from 2000 to 2009, and average NPP for this ten years was 9.92 Tg C. Spatially, annual NPP increased from south to north totally. NPP of Heilongjiang province was higher than that of Jilin province located in wetstern Songnen Plain, which was mainly affected by the climate and soil conditions. During the past ten years, grassland NPP of western Songnen Plain ranked decreasingly as 2008, 2005, 2002, 2007, 2003, 2004, 2006, 2009, 2000, 2001.