Dynamics of spruce and birch populations as a base for stability of north-taiga old-growth spruce forests

Basing on analysis of size and age structure and observation during 9 years within the two permanent plots in Arkhangelsk Region (Pinega district), dynamics of spruce (Picea obovata Ledeb.) and birch (Betula pubescens Ehrh.) populations was described in old-growth spruce forests. Because of rare tree layer, light regime in both communities is favorable: it enhances tolerance of spruce plants to strong soil moisture and reduces mortality in populations. But a lack of drained surfaces restricts recruitment of these populations.