Study of the vegetation of the Southern Prebaikalia and central part of the Eastern coast of Lake Baikal (Barguzin valley) have been done. For vegetation of the Lake Baikal’ basin were obtained dates about current structure an dynamics tendencies of plant communities which forming on the contact of the azonal (extrazonal) steppe and zonal forest, inside of the zonal forest – steppe as well. Some dates about the processes of the steppe areas afforestation for last time period were obtained too. The vegetation of the model territories can serve as a succession system reflecting all possible states of communities at actual endoecogenesis and exoecogenesis of vegetation of concrete territories.