Capacity and regeneration of subtundra forest stands in the Komi Republic

The paper highlights the evaluation results of the productivity and regeneration of stands in the Pechora forestry of the Komi Republic. At the research sites, the stands are mixed by composition and simple to complex by shape (with one or two stories). They are dominated by sphagnum spruce stands of Va - Vb quality classes. The total standing volume of stands varies from 44 to 161 m3/ha whereas the average volume increment varies from 0.49 to 1.46 m3/ha per year. The dependence of standing volume on the absolute and relative forest density is a closely correlated value being reliable at a high level of significance. Young spruce trees grow at 87 % and young birch trees - at 73 % of sample plots. 1/3 of the sample plots is characterized by the density of large spruce new growth exceeding 1.2 thousand units/ha. In this case, we can recommend natural reforestation by young growth conservation and care for it. At the other areas, the forest density varies from 0.25 to 0.8 thousand units/ha. Here, we also think that natural reforestation is an appropriate forest regeneration method but on condition of soil mineralization and with leaving seed trees. The relationship between the density of spruce or birch regrowth and the total stand stock can be expressed by the parabola equations. The maximum density of large spruce regrowth (1.75 thousand units/ha), calculated by these equations, corresponds to the stand stock of 84 m3/ha and relative stand density of 0.93. The maximum density of large birch regrowth (0.95 thousand units/ha) corresponds to the stand stock of 88 m3/ha and relative stand density of 0.98. Along with decreasing or increasing the stand stock value providing for the maximum regrowth density, the regrowth density values decrease. We explain the identified dependency as follows. In the given conditions, the maximum density of large regrowth that can further become a stand, can be achieved on condition of the optimal density and stock of stands that provide favorable conditions for regeneration and growth of young trees. Any decrease or increase in the density and stock of stands from the values being optimal for regeneration and growth of young trees weakens the protective role of maternal stand or, vice versa, increases its negative impact on the younger generation and, as a result, decreases the regrowth density under the canopy. The above mechanisms should be taken into account when conducting selective cuttings and cleaning cuttings under these conditions.