Dynamics of the Spruce Population Structure Under the Canopy of Birch in Coniferous-Deciduous and Southern Taiga Forests of European Russia

A comparative study of a restoration process is conducted in combinational forests of birch and spruce, as a population under the canopy, in the conditions of coniferousdeciduous or subboreal (Moscow region, Mozhayskiy district), and southern taiga or boreal forests (Yaroslavl region, Rybinskiy district) of European Russia. The relevance of investigations in this field is determined by the controversies over the outcomes from the natural course of successional processes in small-leaved forests with spruce growth under the canopy. The permanent trial plots, which were used for examinations, are characterized by the high-density birch forests of the oxalis-blueberry group with a first-class growth quality at the maturity stage, between 60 and 80 years old. The dynamics of age and vertical layers are investigated for the spruce under the canopy and the parcel structure of stand with ages within the 20-year period. It is determined that the main part of the spruce population under the canopy is represented by the generation, which was established in the birch forests until they reach the age of 30. The age composition of the spruce population, the arrangement of renewal periods, and the process of tree falling at the beginning and the end of the birch forests maturity stage are practically similar. In the zone of subboreal forests the vertical structure of the second layer of the spruce population develops earlier, compared to the boreal forests. In the boreal area, the formation of the under canopy second layer of spruce and its development to the first one begins at the aging stage, which is reached by birch trees around 90 years old. It was concluded that there are no fundamental differences in parcel structure of the stand or its fragmentation. In the mixed birch forests under the age of 60–80 years old the following properties are observed: an increase in the monoparcellarity of phytocenoses, in the areas with a closed second layer of spruce rises the occurrence of parcels, the amount of parcel plots declines, while their areas expand. If the birch forests are older than 90 years, monoparcellarity of the phytocenosis structure destroys, the number of parcels increases due to the appearance of gaps in the canopy, spruce renews in the areas the birche group-fall or after the snowfall and gusts of strong wind. For citation: Deryugin A.A., Rybakova N.A., Glazunov Y.B. Dynamics of the Spruce Population Structure Under the Canopy of Birch in Coniferous-Deciduous and Southern Taiga Forests of European Russia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 15–25. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-15-25