VARIATION IN FORESTS FLAMMABILITY AND FORMATION OF FIRE RESISTANT STANDS IN BAIKAL REGION

The article presents data on variations in flammability of the main forest types and associated vegetation complexes in all altitudinal zones in the Baikal region. Potentially high fire hazard of forests in the region is due to the prevalence of softwood forest stands in their composition and a specific climate pattern with long spring-summer dry periods. In especially dry years, the fires quickly engulfed entire landscapes, forest-steppe with softwood taiga. Experimental data were obtained characterising the flammability of different forest types by altitudinal zones: the rate of fire maturation, the duration of the fire hazard state under different meteorological conditions during different seasons, etc. A 2-year long aerial monitoring of the Baikal forests’ flammability was conducted. Despite the generally high flammability of the local forests, the main factors of their fire maturation (atmospheric precipitation and composition of stands) vary widely. In this regard, it should be noted that deciduous stands, including aspen on the southern coast of Lake Baikal, are almost incombustible. The predominant background of coniferous forests is formed by larch stands Within them, ground fires are the main ones occurring, and crown fires are possible only in dry types of young forests. These data should be used in the selection and formation of fire-resistant areas (barriers, belts) in forest areas in order to form, in combination with other fire barriers, a closed systemof forest stands resistant to the pyrogenic factor. With regard to especially valuable and visited forests it is proposed to devise an appropriate scheme of fire-prevention arrangement and modernisation of forestry measures, including regeneration cuts and reformation of stands. Regional technologies for the construction of fire barriers from fire-resistant stands have been developed. Fire barriers 250—300 m wide are recommended to be formed on both sides of main roads passing through stands of pine, cedar, spruce and fir. These barriers are intended to reliably stop the front of external crown fires. The barriers are bordered by clearings along which mineralized strips 3—4 m wide are laid. In places where the barrier passes through monoconiferous forest stands, it is necessary to arrange longitudinal corridors with mineralized strips every 20—30 m. Fire-resistant edges 80—100 m wide or less are advisable to form along separate secondary roads to divide the forest massif into second-order blocks. Further differentiation of the developed territory into third-order blocks is carried out by laying mineralised strips using other kinds of existing fire obstructions, which must be necessarily interconnected into a closed network, allowing for the immediate elimination of possible fires in the very beginning.