Climatic Conditions of Steppe and Tundra Formations in the Altai Highland Depressions

Abstract

Data on the climate and vegetation of the Altai highland depressions are mapped in this paper. The Bertek depression (located 2200–2400 m above sea level) and the lake depression of Khindiktig-Khol’ (2300–2400 m a.s.l.) were chosen as study objects. The investigation is based on information about vegetation and microclimatic differences obtained during 2018 field research. Long-term observations of Bertek and Mugur-Aksy meteorological stations are applied to climate characteristics. Steppe vegetation is typical for the depressions. Tundra species also exist alongside steppe ones within the Khindiktig-Khol’ region, though in some cases a mosaic of tundra and steppe is found. Tundra communities are insignificant within the Bertek depression. Vegetation cover of the depressions develops under the conditions of a short-term vegetation period and undergoes the negative impact of low summer temperatures (mean July temperatures in Bertek are 9.3 °С; in Khindiktig-Khol’—10.8 °С). The data are significantly lower than the mean temperatures of the flat steppe zone. Taking into account the temperature data, the investigated areas are associated with the tundra zone. The climate humidification level is not enough to develop the continuous cover of tundra cenosis (Vysotskii-Ivanov’s precipitation- evaporation ratio of Khindiktig-Khol’ equals 0.74; in Bertek — 0.61). According to the fact above, the Khindiktig-Khol’ depression is more humid, and the tundra communities live together with the steppe vegetation. Microclimatic observations of the neighboring areas with different tundra and steppe cenoses show that the species composing tundra with the dwarf birch (Betula rotundifolia) have unique features that create favorable conditions for the existence of this community. In comparison with the steppe area, the air during the daytime heats up better not only above the tundra pattern, but also beneath it. Moreover, the dwarf birch (Betula rotundifolia) maintains snow cover, which results in better soil humidification. Consequently, the vegetation cover is more diverse in the Khindiktig-Khol’ depression, making it possible to figure out the appearance of its exclusive tundra and steppe mixture.