REPLACEMENT OF DOMINANTS OF FOREST FORMING SPECIES IN PRE-BAIKALIAN AND TRNAS-BAIKALIAN FORESTS (The Baikal Region)

Found out the structural-dynamic organization and trends in light-coniferous forests development under different physical-geographic conditions in some areas of the Baikal Region. In light-coniferous forests consisting of larch (Larix sibirica) and pine (Pinus sylvestris) with inclusion of birch (Betula platyphylla) and aspen (Populus tremula) of different typology in subordinate synfolia there are such dark-coniferous species as cedar (Pinus sibirica), sometimes spruce (Picea obovata). Cedar dominance in the undergrowth was revealed everywhere, while occurrence of modern forest-forming species such as pine and larch counts only several specimens. Cedar is often considerably represented on the places of burnings and cuttings, which took place in different years, where a timber stand of small-leaf trees species (birch, aspen) formed together with their underwood. Due to this fact, we can suppose that the probability of replacement of dominant from light-coniferous species to dark-coniferous component in the light-coniferous forests of the studied area is rather high. Presence in the soil cover of plants species characteristic for mixed light-coniferous – dark-coniferous forests can confirm the existence of potential for the developments of dark-coniferous taiga on the background of probable decrease of pyrogenic factors and of cuttings of different form and intensity in the region. By many factors, the forests in the studied area where forest-forming trees species are replaced are indicators of modern changes in the forests structural-dynamic organization on the background of dynamics of natural-climatic factors in the Baikal Region. It is found out that in the subordinate synfolia of light-coniferous forests in South-Eastern Pre-Baikal and South-Western Trans-Baikal, initial stage of dark-coniferous taiga is found out.