Calculations of the activity indices and species richness of belt-zonal elements of the flora of Baikal region forests have been done in order to reveal the presence of climatogenic changes. The results provided evidence for the weakening status of xerophilic species in the floristic composition of hemiboreal light coniferous forests (with dominance of Pinus sylvestris). On the contrary, no significant change has been observed in the floristic composition of mountain light coniferous boreal forests (with dominance of Larix gmelinii). Besides, it was found that there was an increase in activity of the species of the dark-coniferous belt-zonal group peculiar to dark-coniferous boreal forests (with dominance Abies sibirica and Pinus sibirica).