Scientific publications

The dynamics of valuation characteristics and formation of a herb-sphagnum spruce stand during 30 years after site drainage and a clearcut with understory and polewood retention were studied. Growing stock increment was the highest (9,3 m³/ha per year) in the third decade, which is typical of a bilberry spruce stand of quality class I growing on mineral soils in Karelia. Thirty years after the harvest the stand’s total growing stock was fully regenerated. The shares of largeand medium-size timber increased by 30% compared to their stock before the harvest. Drainage and thinning improved the conditions for understory growth and its more intensive recruitment in the commercial stock. The number of spruce trunks increased 2,3-fold 30 years after the harvest, now being more than 1000 per ha, which is sufficiently high for a high-productivity spruce stand to form on drained land. During the first three years after thinning, die-back in spruce stands on peat soils accelerated (106 trees per 1 ha). After that, as the plants grew adapted to the new situation, die-back steadied out at the level typical of undisturbed forest. Conversion cuts in birch-spruce stands have doubled their productivity, and all of the added max current increment (8,8 m³/ha per year) was in the most valuable spruce component of the stand. By the end of the 30-year period the stock has fully regenerated, and rose to 205% of the pre-harvest size. Up to 53% of total stock accrual happens owing to the understory. The rate of understory recruitment is higher than the rate of die-back, proving the drained spruce and birch-spruce stands are resilient against thinning.