The historical methods of forests research at fixed sites continue to be the most reliable way of collecting information about the processes of tree stand formation, differentiation, and the onset of various age stages. The article presents the results of 70 years of observations at a permanent sample plot located in waterside buffer forests at Lake Karasye in the Yemtsovsky Training and Experimental Forestry District of the Obozersky Forest Management Unit (Plesetsky District, Arkhangelsk Region). Baseline surveys were carried out and the permanent sample plot was established in 1952 under the guidance of Associate Professor V. I. Kalinin. Subsequently, measurements were repeated by students under the guidance of professors of the Northern (Arctic) Federal University (previously Arkhangelsk Forest Technology Institute and Arkhangelsk State Technical University). Long-term monitoring shows that, despite the old age, the stand continues to be highly productive. The stand evolves through tree-fall dynamics, with shadetolerant spruce regenerating successfully in the gaps forming after the fall of old pine and larch tree. Studies show that a spruce forest with an admixture of larch, pine and birch is replacing the mature pine-larch tree stand. The forest register data show the area occupied by larch stands in the Arkhangelsk Region is gradually declining. This may be due to the tendency to underestimate of the larch share during valuation inventories. The conservation measures such as excluding stands comprising 30 or more percent of larch from logging plans have proved ineffective. Monitoring in permanent sample plots shows that the stand’s growing stock composition will usually change from larch to spruce. To ensure larch restoration at the limit of its distribution range in the Arkhangelsk Region, actions to promote its regeneration and artificial planting are needed.