TRENDS IN DYNAMICS OF FOREST UPPER BOUNDARY IN HIGH MOUNTAINS OF NORTHERN BAIKAL AREA
V. I. Voronin, V. A. Oskolkov, V. A. Buyantuev, A. P. Sizykh
Siberian Institute of Plants Physiology and Biochemistry, Russian Academy of Sciences, Siberian Branch, Lermontov str., 132, Irkutsk, 664033 Russian Federation
Keywords: экотон верхней границы леса, лиственница даурская, лесовозобновление, радиальный прирост, Северное Прибайкалье, ecotone of the forest upper boundary, Daurian larch, forest regeneration, radial increment, northern Baikal area
Abstract
Studies of spatial-temporal variability of the upper boundary of the forest on the north-western coast of Lake Baikal (Baikal and Upper Angara Ridges) are performed on the base of the analysis of forests renewal processes and of the dynamics of larch radial increment in the ecotone of the forest upper boundary and out of it. The presence of a large amount of well-developed uplands and circuses with considerable heights drops in the structure of mountain system favours formation of interrupted boundary between forest and subgoltsy belt. The timber stand of the upper forest boundary in the studied area is represented by Daurian larch. Three tree-ring chronologies of larch are obtained. The longest chronology is obtained for mountain taiga belt of Baikal Ridge and is as long as 460 years. Since 1980ies, a sustainable trend of increase of radial trees growth is observed. It is observed the most distinctly in trees of the upper forest boundary on the Baikal Ridge. There is advancing of trees species into subgoltsy belt and into mountain tundra, which depends, respectively, on slopes heights, exposition and tilting, on sites of growth of concrete cenoses. Modern peculiarity of the vegetation of the studied area is presence of abundant viable larch undergrowth (from 2-3 to 25 y.o.) and fir in the ecotone of upper forest boundary and in subgoltsy belt, as well as appearing of single specimens of spruce. Main undergrowth mass (2/3) is presented by trees aged in average 15-25 y.o., i.e., they appeared in late 1980ies. Due to increase of snow cover thickness in winter, the trees young growth obtained great protection from freezing resulting in the increase of ability of young growth to live up to elder age.
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