Calculation of vegetation indices, especially Normalized Difference Vegetation Index (NDVI), has become one of the most successful, popular and traditional attempts in biogeographical research methods, because NDVI has certain advantages over other vegetation indices or band combinations. Producing vegetation indices has been done in this research using mathematic calculation of the channels: (NIR-VIS) / (NIR+VIS), or a ratio for channels: (Band4-Band3) / (Band4 +Band3). Monitoring spatial distribution, presence and health conditions of the vegetation is traditionally being performed using calculation of the NDVI. To model the NDVI I used Map Calculation tool in command line of the Raster Operations menu in ILWIS GIS, which enables to perform spatial analysis and modeling by combination of queries, arithmetic expressions and overlays of selected raster images. The resulting images shows distribution of the vegetation over the Bovanenkovo region within three (3) years: 1988, 2001 and 2011. The results for the year 2001 show that vegetation has very moderate overall index, reaching value 0,500 as a maximal. The maximal NDVI values in year 2011 are 0.49, while in 1988 it was 0.76, which shows the decrease in the biomass values during the past two decades. The satellite-based monitoring of the northern ecosystems is important tool for detection of the environmental changes, which has been demonstrated in this paper.