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THE EFFECT OF ALTERNATIVE THINNING REGIMES ON GROWTH AND STABILITY OF SCOTS PINE PLANTATIONS IN SOUTHERN FOREST-STEPPE IN UKRAINE
Authors: Oksana Tarnopilska, Sergiy Musienko, Oleksandr Lyalin, Ludmila Tkach, and Vira Babenko
Number of views: 408
The effect of selective and combination (row + selective) thinning of varying intensities on
mensuration characteristics, differentiation, and productivity of middle-aged plantations of Scots
pine was studied in southern Forest-Steppe in Ukraine. The experiment on thinning by combination
method in planted Scots pine (Pinus sylvestris L.) stands was established in 1967 in
16-year-old pine plantations. The plantations were created in 1950 by one-year seedlings with 1.5
× 0.7 m spacing. The initial density of the stands was 9.5 thousand stems per ha. The experiment
included five variants of different thinning regimes: selective thinning of moderate intensity; combination
thinning with removal of every 4th row; combination thinning with removal of every 3rd row;
combination thinning with removal of every 2nd row; combination thinning with removal of every 4th
row at 16 years followed by combination thinning of middle rows at the age of 23. Thereafter, up
to 40 years of age, the plantations were thinned twice using selective thinning from below of low
and moderate intensity – 24 % by the growing stock volume. During the thinning, the plantations
were kept to a specified density. 64-years-old planted Scots pine stands with a density of about
650 stems∙ha-1, in which thinning was carried out by selective method of moderate intensity and
by combination (row+ select thinning) method of moderate and high intensities (with complete removal
of trees in every 2nd, or 3rd, or 4th row) at the age of 17 and the subsequent selective thinning
of moderate intensity, are scarcely different in mensuration characteristics. The best method was
the combination thinning with the removal of each 3rd or 4th row; the method can be recommended
for practice, given the high mensuration characteristics, productivity, and resistance of the thinned
stands against a physical load.