VEGETATION RESISTANCE OF GEOSYSTEMS IN THE DEPRESSIONS OF NORTHEASTERN CISBAIKALIA TO THE PYROGENIC FACTOR
A.P. Sofronov1, I.N. Vladimirov1, V.I. Voronin2, E.V. Sofronova1
1V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
2Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: vegetation resistance to pyrogenic factor, geobotanical mapping, Northern Baikal and Upper Angara depressions, forest fires
Abstract
The study of vegetation stability remains an important and poorly developed issue of geobotany. Results from studying of resistance to the pyrogenic factor of plant communities of vegetation cover of the North Baikal and Upper Angara depressions are presented. In recent years, fires have become catastrophic in Siberia as well as on the territory of the country as a whole; therefore, the pyrogenic impact came to be one of the main negative anthropogenic factors. We suggest an original technique for determining the parameters of vegetation resistance to the pyrogenic factor, based on assessing the ignitability. The susceptibility to fire of both individual plant species and plant layers of cenoses, and also the degree of damage by fires have been comprehensively studied, with due regard for the mesoclimatic conditions and areal distribution throughout the territory. It was established that the resistance of the communities can vary according to on their hierarchical rank. As a result of the research, a legend and a medium-scale map of the vegetation resistance in the region to the pyrogenic factor have been generated. It was revealed that the most stable communities are sparse alpine tundras, alpine meadows and meadow-swamp communities of the Upper Angara floodplain and wet forests of mountain valleys. The medium-stable cenoses include tundra watersheds and sloping summits with well-developed shrub-lichen cover, sparse communities of Pinus pumila, small-leaved forests, steppe slopes and forest communities of the floodplain. The smallest degree of stability is typical for closed P. pumila thickets, subgoletz dark coniferous-larch forests, mountain taiga dark coniferous forests, as well as for pine forests of the submontane-depression belt. An important characteristic of the stability of the communities is the duration of recovery of the primary (conventionally primary) state. It is shown that the accessibility of natural communities to humans significantly affects the resistance of vegetation to the pyrogenic factor, because this greatly increases the likelihood of fire in any of the cenoses considered.
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