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

The data on 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.) are decided to be the study objects. The investigation is based on the information about vegetation and microclimatic differences received during the field research in 2018. Long-term observations of Bertek and Mugur-Aksy meteorological stations are applied to climate characteristics. The steppe vegetation is typical for the depressions. The tundra species also exist alongside the steppe ones within the Khindiktig-Khol’ region, though in some cases the intarsia of tundra and steppe is founded. Tundra communities are insignificant within the Bertek depression. Vegetation cover of the depressions develops under the conditions of short-term vegetation period and undergoes the negative impact of low summer temperatures (mean July temperatures in Bertek – +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, whereas in Bertek – 0,61). According to the fact above, Khindiktig-Khol’ depression is more humid, and the tundra communities live together with the steppe vegetation. Microclimatic observations of the neighboring areas with the different tundra and steppe cenoses show that the species, which are composing tundra with the dwarf birch (Betula rotundifolia), have unique features, thus creating favorable conditions for the existence of this community. Comparing to the steppe area, the air during the daylight heats better not only above the tundra pattern, but also beneath it. Moreover, the dwarf birch (Betula rotundifolia) keeps the snow cover, which results in a better soil humidification. Consequently, the vegetation cover is more diverse in Khindiktig-Khol’ depression and allows to figure out the appearance of exclusive tundra and steppe mixture.