As a result of field studies on meridional transects (58.1° - 67.0°N, Republic of Karelia, Murmansk, Vologda, Arkhangelsk, Leningrad, Novgorod, Tver regions), distributions of vegetation indicators by latitude were obtained: the number of vascular plant species in the ground cover, the number of shrub species, the share of index of power of dwarf shrubs, bog dwarf shrubs, boreal and nemoral herbs in the total index of power of species of grass-shrub layer, average height, projective cover and stock of tree stands. Based on the analysis of these distributions, conclusions are drawn about shift in the northern direction (regarding the boundaries adopted in the XX century): the boundaries of the northern and middle taiga, the middle and southern taiga by 0.5-1° (40-130 km). Taking into account the established changes in climatic parameters over the past 30 years, the shift of the boundaries of the taiga subzones and the taiga zone as a whole in the western part of European Russia to the north is due to a significant increase in the heat supply of the territory in recent decades.
Based on the data of the monitoring observations in Leningrad region, the dynamics of oak (Quercus robur) undergrowth for the period 2006-2020 was analyzed. Studies confirm the distribution of oak over the past 20 years in the main types of landscape sites of the southern taiga of the North-West of the European Russia, which indicates the expansion of oak beyond the most favorable sites in which oak grew in the southern taiga in the XX century. This expansion, along with the oak moving northward 70-150 km from the northern limit of its areal, is caused by climate warming over the past decades.