Age structure of the birch stands in the Left-Bank Forest-Steppe of Ukraine

The aim of this work was to define the features of the age structure of the silver birch stands in the Left-Bank Forest-Steppe considering forest site conditions, origin, site index and proportion of this species in the forest composition. Survival of silver birch in almost all age classes was the lowest in the relatively poor forest site conditions. The mean weighted age classes of silver birch are IV.8 in vegetative stands and IV.6 – in artificial seed stands. For all origins, the mean weighted age classes are V.1 for Sumy Region and IV.6 – for Kharkiv and Poltava Regions. The stands of the lower productivity have the least longevity. Survival of pure and almost pure stands (silver birch make 90 % of all the trees) is the lowest. At that, it is the highest in Sumy Region.