The paper describes the methodology for processing remote sensing data to indicate pyrogenic effects on natural geosystems. Autumn season space images (from the end of the firedangerous period to the beginning of the formation of the snow cover – the end of September to the beginning of October) with a less than 20 % cloud level were preferred. The area affected by fires within Priolhonye in the period since 2013 to 2015 years are analyzed. According to the obtained data it has made more than 200 km2. Pyrogene impact on Priolkhonye geosystems considerably amplifies amidst transforming environmental factors (climate warming, decrease in water level of the Lake Baikal and all that) and anthropogenic impacts, that is lead to change in the structure and rate of physiographic processes. In the conditions of the changing environment of geodynamic active area this impact on Priolhonye geosystems can be disastrous and lead to their irreversible transformation. In particular, disturbed geosystems of cedar forests by fire will could change to pine-larch forests through the birch series. In particular, the destructive effect of the pyrogenic factor on steep slopes with pine-larch rarefied groups of facies leads to the destruction of its invariant structure and replacement by steppe small-graingrassy lithophilic ones.