Features of the Horizontal Structure of Forests of Spruce Formations in the European Taiga of Russia

Abstract

The article highlights the issues of studying the structure of indigenous forests of different ages as a model of sustainable forest formations. The research purpose is to study the patterns of horizontal structure formation of indigenous virgin spruce forests of the northern, middle and southern taiga subzones of European Russia. We consider the nature of the horizontal structure as one of the most important signs of sustainability of forest communities developed over the evolution. Indigenous virgin spruce forests in each of the taiga subzones of European Russia were adopted as research objects: spruce forests of the Severodvinsk forestry of the Arkhangelsk region in the northern taiga subzone; spruce forests of the Vepsky forest reserve in the middle taiga subzone; spruce forests of the Central Forest Nature Reserve in the southern taiga subzone. Sample plots were laid out in biogeocenoses, where we studied the age, horizontal, and pathological characteristics of spruce forests. Continuous tree drilling was carried out to determine the age of trees and their infestation by wood-destroying fungi of the biotrophic complex. The mosaics of age generations were identified on the plans of sample plots; the area of each of them, the volume of trees in the mosaics and the homogeneity by age, and the amount of natural regeneration were determined. Indigenous spruce fir forests of the taiga of European Russia have a different age structure with a different number of age generations in the age series and various dynamic indicators of biogeocenoses. All of them have a mosaic arrangement of trees grouped by different age generations, growing in different sized areas and distinguished by an unequal degree of homogeneity in terms of age. This defines a complex age horizontal and vertical structure of biogeocenoses; the most important condition for sustainability of forest communities. Accounting of spruce natural regeneration showed significant differences in the number of undergrowth in spruce forests of different taiga subzones, which refers to a variety of horizontal structures of such forests. The ratio of the number of spruce undergrowth growing on decaying trunks of woody debris and on the ground is as follows: the number of 0.5 m high undergrowth in both growing conditions is almost equal, the number of over 3 m high undergrowth on deadwood trunks is less compared to the number of undergrowth of this height category on the ground.