Current state and evolution history of vegetation cover in Krasnoufimsk forest-steppe

The biodiversity of current flora in forest-steppe of the Cis-Uralian area in Sverdlovsk Region (Krasnoufimsk forest-steppe) according to many years of research is revealed. Steppe flora is represented 960 species of vascular plants, which belong to 105 families and 403 genera. The analysis of flora is made using an electronic database. It can be related to the Mediterranean Fabaceae-type by the spectrum of basic families. The analysis of life forms revealed that the prevailing in the flora is the grassy one (90.3%). A significant part of the cenosis spectrum are weeds and eurytopic species (25.5%) because of the anthropogenic impact on the area. Visible mesophyte dominance in the flora (49%) determines the character of the forest-steppe. The location determines peculiarities of the formation of flora in Krasnoufimsk forest-steppe. This area is the arena of collision and inter-penetration of different floras. There are many species of the Eurasian (36.3%), Holarctic (17.7%) and Europe (170%) geoelements. Currently, the foundation of flora is represented by the boreal floristic complexes involving forest-steppe and steppe species. The local nucleus of the flora is 9.7% of the total number of species. It includes a significant number of endemic and relict species of different historical time. We need to note that although the nature of the forest-steppe flora is preserved, its trend is boreal by the current ecological spectrum and the relation of cenosis groups. The structure of vegetation cover and its change over time (17th-20th centuries) using the geo-botanical maps, including archive ones, is shown in the article. The historical depth of transformation into forest-steppe is determined by three centuries that had an appropriate environmental impact. Now natural ecosystems in forest-steppe cover only 25% of the territory, including: forests - 14%, meadows - 7%, steppes - 4%. A retrospective analysis of phytodiversity of the area takes into account the paleobotanical data from other works on the topic. The family of woody-shrub vegetation type (Betulaceae, Salicaceae) dominated in the pre-boreal period. Currently the families Asteraceae, Poaceae and Fabaceae are represented by the largest number of species. Consequently, there was a change of the tundra-shrub landscape to mesophilic forest-steppe. The studied area of Krasnoufimsk forest-steppe can be regarded as an independent phytochorion at the rate of a district belonging to the Eastern European steppe province of the Eurasian steppe region by the nature of its flora and vegetation.

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