FORMATION OF SIBERIAN PINE FORESTS BY IMPROVEMENT FELLING ON FORMER AGRICULTURАL LANDS
On the base of the researches carried out on the permanent study area silvicultural effectiveness of improvement felling was analyzed in soft-leaved plantations formed on the former agricultural lands in Khanty-Mansi Autonomons Okrug - Yugra. It was experimentally found that among 25-30-year-old soft-leaved stands there is Siberian pine ( Pinus sibirica Du Tour); besides this, nominal undergrowth of this species can be found under the canopy. Improvement felling can provide an increase in the share of Siberian pine in the composition of the forming plantations and even its dominance in stands. It is recommended to carry out improvement felling by the strip method. On the first-stage the felling of soft-leaved species in strips of 10 m wide is carried out, while leaving strips of similar width without care. On the second stage in 10 years soft-leaved trees are cut down in those strips where care was not taken. Felling of all the accompanying Siberian pine trees in a single shot is inadmissible, since it leads to intensive growth of herbaceous vegetation, sodding and exclusion of the Siberian pine undergrowth as well as dramatically increases the fire danger in spring and autumn. In addition, at the indicated intensity, the specimens of Siberian pine left for cultivation are affected by Pineus cembrae (Cholodovsky, 1988).