Abstract
Representations of Pleistocene cryophyte steppe periods as well as of the climate of modern Northeast Asia are associated with high continentality of climate. To what extent and in what way the distribution of steppe landscapes in the past and modern isolated steppe centers is associated with climate continentality has not been specifically studied yet. In this paper, the basins of the upper reaches of neighboring rivers, the Indigirka and Kolyma, are considered as a model. In the first basin steppe communities on the southern slopes of the valleys occupy an important place in the landscape, on a background of permafrost larch and Siberian dwarf pine communities. In the upper Kolyma River and further north, east and south, the area of steppe communities and diversity of steppe plants and invertebrates decreases sharply. A comparison of 28 characteristics of temperature regime, humidity and climate continentality indices revealed that the differences between the aforementioned regions are reliable and substantial only in winter. It cannot be excluded that the extensive distribution of steppe associations in the headwaters of the Indigirka is influenced by factors other than climate, such as the distinctive biogeochemical characteristics of the territory. The analysis of seasonal indicators of continentality may prove to be an important factor in the understanding of the climatic causes of past tundra-steppe dominance in the Northeast Asia.
