Spectral Characteristics and Modified Vegetation Index of ihree Main Plants of Seriphidium transiliense Desert Grassland

【Objective】 Seriphidium transiliense desert grassland is an important part of grassland ecosystem in Xinjiang. The study of the main plant ground spectrum and vegetation index characteristics is the basis to realize species identification, which is of great significance to obtain the change of community species composition accurately and timely, and to improve the quality and effect of grassland monitoring. 【Methods】 In this study, SOC 710 VP imaging spectrometer was used,hyperspectral images of desert grassland community of Seriphidium transiliense desert grassland in April were collected,Seriphidium transiliense, Ceratocarpus arenarius and Petrosimonia sibirica were extracted respectively. The spectral discrimination was improved by the transformation of reflectivity (REF), absorptivity (ABS) and its first-order differential (GREF and GABS) and the sensitive band was analyzed and screened out. Then the NDVI’ undefined value and DVI’ undefined value were calculated by the combination of each band, and the maximum vegetation index was selected by taking the NDVI value and RVI value calculated by the whole band as a reference. 【Results】 (1) The spectral curves of the three main plants were similar, and the difference was mainly reflected in the spectral value. The reflectivity of the three main plants showed the characteristics of Ceratocarpus arenarius > Seriphidium transiliense > Petrosimonia sibirica > community in the visible light 400-780 nm and near infrared band 780-820 nm; (2) The spectral characteristics of the first order differential reflectivity GREF and the first order differential absorptivity GABS could be further expanded by the transformation of the reflectivity REF, absorptivity GREF and the first order differential absorptivity GABS. The relatively stable band had the blue light band 490-530 nm, green light band 510-560 nm, red light band 620-760 nm and near infrared band 780-820 nm. (3) The difference between the NDVI' and RVI' calculated by the combination of 490-530 nm and 780-820 nm bands under the GABS and ABS transformations was greater than the NDVI' and RVI' calculated in the full and other bands across the three major plants. 【Conclusion】 The first-order differential treatment of reflectivity and absorptivity in the sensitive band and the improvement of vegetation index can improve the recognition effect of three main plants in Seriphidium transiliense desert grassland.