ИСТИНА

The Great Vasyugan Mire, situated in West Siberia, is the largest wetland system in the northern hemisphere and covers about 55 000 km². Mire extent from west to east is about 550 km, and from north to south with branches reaches 270 km. Such wide expanse results in a great diversity of mire environments. In this study, the land cover classification for the entire Great Vasyugan Mire based on Landsat 7 images was completed and used for the quantification of methane emissions from this area. Forests, wetlands and some other ecosystems were partly masked by normalized difference and green-red vegetation indexes. Forest and wetland differentiation by «summer» and «winter» images also showed good results. Mask and classified image errors were filtered out using original algorithms written in Matlab. A supervised classification of masked image was carried out using bands 4–5 and 3 of LandSat ETM. Thirteen land cover classes of aquatic and terrestrial environments were assigned by the classification approach. Total methane emission was further estimated on the base of data from 10 key sites subtaiga and south taiga zones. It was found that forested raised bogs with dwarf pine-shrub-sphagnum communities and patterned bogs are dominating (23.9 and 18.5% of whole area, respectively). Complex mineratrophic poor fens with Carex lasiocarpa follow covering 18.9% of the total area. The later are substantially typical for The Great Vasyugan Mire. Poor fens with domination of sedges or buckbean are wide spread covering 18.7% of the total area, too. Lesser areas are occupied by different types of forested fens (13.8%). The rest of the region is occupied by aquatic ecosystems (peat mat and ponds – 4.3%, lakes – 0.8%) and drained wetlands (1.1%).