【摘要】 以黑河流域为研究区 ,探寻基于TM影像提取的植被指数 (VIs)与野外实测数据间叶面积指数 (LAI)的反演研究。结果表明 ,各植被指数与LAI均具有较高的相关性 ,整个研究区土壤调整植被指数 (SAVI)具有最高的LAI反演精度 ;把研究区分成绿洲区和山区 ,各种植被指数与LAI的相关系数和反演精度均有很大程度提高 ,同时得到绿洲区SAVI最适于反演LAI ,山区SR最适于反演LAI ,通过这种方式估算出黑河流域叶面积指数图。更多还原

【Abstract】 Leaf area index (LAI) is a parameter of the vegetation structure, and is important for quantitatively analyzing many physical and biological processes related to the dynamic change of vegetation and its effects on the change of the global environment and climate. In this paper, the LAI is estimated for the Heihe River watershed based on the correlations between the field-measured LAI andthe vegetation indexes with some environmental problems restricting the regional environment development in the watershed. After making the geometric, topographic and atmospheric corrections of a synchronous high-solution Landsat TM image,four vegetation indexes (NDVI, SAVI, SR and RSR) are derived, and their separate correlations with LAI are investigated. According to the elevation, the study area is divided into the oasis area and the mountainous region. The analyzed results of the linear and nonlinear relationships between these vegetation indexes and LAI are as follows: (1) The relationships between NDVI and SAVIversus LAI are essentially linear, they do not occur to be a saturation point at high LAI. As for SR and RSR versus LAI, the exponential relationship occurs to be more appropriate than the linear relationships, and it will saturate at high LAI point. (2) SAVI shows the best for LAIretrieval in the whole study area, when the study area is divided into the oasis area and the mountainous region, the correlations of these four VIs with LAI are evidently improved; in the oasis area, SAVI has the highest accuracy of LAI retrieval; whereas in the mountainous region, SR exhibits the best. And it also reveals that SR shows better for LAI retrieval than NDVI, RSR may be not suitable for LAI study in the Heihe River watershed. (3) If there are enough field-measured data for LAI study in the arid and semi-arid regions with complicated terrain, such as the Heihe River watershed, it will show better results when the study area is divided into the mountainous region and the oasis area. By dividing the study area into two different areas, LAI mapping for the Heihe River watershed has been obtained, and the results have been applied for the hydrological and ecological studies in the area.更多还原