Search

The results of studies of the Late Pleistocene and Holocene spore–pollen spectra and the microtheriofauna of loose deposits of four cave localities located in the Shchuger and Kozhym river basins within the territory of the Yugyd-Va National Park on the western slope of the Subpolar Urals are discussed. Assessment of the age of sediments from the karst cavities was based on the data of AMS radiocarbon dating of mammalian bones. The speleogenic formations of the localities studied contain layers assigned to the final stage of the degradation of the Polar Ural (Late Valdai) glaciation (Middle to Late Dryas) and to the Preboreal, Boreal, and Subatlantic periods of the Holocene. Cryoxerophilous tundra species predominated (88.3%) in the fossil microtheriofauna assemblage identified for the Allerod. The Middle Dryas and Allerod, the cold and warm periods of the Late Glacial, respectively, were reflected by the spore–pollen spectra. The microtheriofauna on the western slope of the Subpolar Urals remained quite cryophilous by the end of the Late Dryas. The broad distribution of yernik thickets and goosefoot–gramineous–mixed herb assemblages during that time has been established. The vegetation of the western foothills of the Subpolar Urals consisted of grass–shrub tundra with sparse spruce trees during the Late Preboreal cooling period. The microtheriofauna community also had a tundra-like composition. The presence of dark coniferous taiga forests in the south of the Subpolar Urals and sparse spruce–birch forests with pine and dwarf birch in the undergrowth in the north of the area during the Boreal period has been established. The rodent fauna acquired a forest-like character by that time. Northern taiga dark coniferous forests of spruce with a significant admixture of pine developed on the western slope of the Subpolar Urals by the middle of the Subatlantic period, and the content of tundra elements in the stands increased by the end of this period. The microtheriofauna of the studied region had a typical forest appearance characteristic of all Late Holocene taiga communities in northeastern Europe.

The results of studies on small mammal bone assemblages from seven cave-type sites on the Shchugor and Kozhim rivers are presented. Four stages in the development of small mammal fauna in the Nether-Polar Urals are described, which correspond to the Allerod, Younger Dryas, Early Holocene, and Subatlantic periods. The moderately cryohydrophilic fauna of the Allerod was replaced by an atypically "mild" xerophylic community in the Younger Dryas. In the Early Holocene, its structure still included considerable proportions of tundra species, which, along with forest species, were also found in the subfossil assemblage from the Subatlantic. It is shown that the transformation of the small mammal fauna in the above sites had a specific pattern, compared to that in other regions of northeastern Europe and to the dynamics of the natural environment and climate.