Аннотация:Norway spruce (Picea abies (L.) H. Karst.) is a primary forest-forming species in theEuropean part of Russia, both in terms of its distribution and economic importance. Anumber of studies indicate that one of the reasons for the disturbance of spruce forests islinked to rising temperatures, particularly the detrimental effects of extreme droughts. Theaim of our research is to identify changes in the structural and functional organization ofmature spruce forests at the center of the East European Plain. The study was conducted inintact spruce forests using resurveyed vegetation relevés within the Smolensk–MoscowUpland, with relevés repeated after 40 years (in 1985 and 2025). Changes in structuraland functional parameters of spruce communities were analyzed. The results showed thatsignificant disturbances of the tree layer led to changes in the vegetation of subordinatelayers, as well as the successional dynamics of spruce forests. It was found that followingthe collapse of old-growth spruce stands, two types of secondary succession developed:(1) with the renewal of spruce and (2) with active development of shrubs (hazel and rowan)and undergrowth of broadleaved species. It was also demonstrated that the typologicaldiversity of the studied communities changed over 40 years not only due to the loss ofthe tree layer and the formation of new “non-forest” types but also because several mixedspruce-broadleaved communities transitioned into broadleaved ones, and pine–sprucecommunities of boreal origin shifted to nemoral types. An analysis of the complete speciescomposition of spruce forests based on Ellenberg’s scales scoring revealed changes inhabitat conditions over the 40-year period. A noticeable trend was an increase in theproportion of thermophilic and alkaliphilic species, indicating a shift toward a nemoralvegetation spectrum. It is expected that under the current forest management regime, thenext 40 to 60 years will see a decline in the proportion of spruce within mixed stands,potentially culminating in the complete collapse of monospecific spruce forests in the centerof the East European Plain.