Circumpolar Arctic Floristic Provinces - West Siberian Group
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Circumpolar Arctic Floristic Provinces - West Siberian Group.
Yurtsev (1994) states that this group " …covers the whole West Eurasian sector of the true Arctic (from 67° to 82° N); it is subdivided into [three] subprovinces, each corresponding to a major geomorphological unit. They form a natural swarm, its 'nucleus' being the mountain axis Ural-Pay Khoy-Novaya Zemlya, which runs through several vegetation zones from steppe into polar desert."
"The obvious negative features of the province are: the absence of (1) East Siberian, East Siberian-North American and North American species: (2) North Atlantic Hypoarctic and boreal species (and Arctic-alpine species such as Alchemilla alpina); (3) boreal and even boreal-nemoral taxa, e.g. Calluna vulgaris and Nardus stricta. There are few endemic and other differential taxa in the province or its subprovinces, i.a. Gastrolychnis angustiflora s.s., Papaver lapponicum ssp. Jugoricum, Pedicularis dasyantha, P. sudetica ssp. arcto-europea. The longitudinal floristic gradient is complicated by an 'inversion' in the Ural-Novaya Zemlya subprovince where the East Siberian species (and partly, the amphi-Atlantic) are better represented than in the adjacent lowland areas (Igoshina 1966). The presence of species of the genera Alchemilla, Euphrasia, Gnaphalium, Hieracium etc. is a distinctive feature of the Atlantic sector. The flora of this province was subjected to the destructive action of Quaternary marine transgressions and glaciations (Tolmachev 1970) as well as to the expansion of forest and shrub vegetation. Most favorable for the dispersal of Siberian and East Siberian continental elements was the cold and dry period of the Late Pleistocene, synchronous with the great sea regression." (From Yurtsev 1994.)
- Karnin-Pechora sector
"Here we find most northward extensions of boreal species (in particular European), even on the Kolguyev Islands. The Arctic and Arctic-alpine complex is impoverished, endemism is very poor and of a low rank (e.g. Gentiana arctica, Koeleria pohleana). Some oceanic species penetrate, e.g. Calluna vulgaris, Ligusticum scoticum and Primula farinosa into the western parts of the subprovince and of continental species, e.g. Astragalus umbellatus, Salix nummularia and Trifolium lupinaster, into the eastern parts (of the Ural). Few East Siberian species—absent in the West Siberian lowland and present in the Ural Mts.—occur sporadically, e.g. Crepis chrysantha and Silene paucifolia." (From Yurtsev 1994.)
- Polar Ural-Novaya Zemlya sector
"The mountainous relief and the diversity of rocks and the expansion of forest and shrub vegetation favoured the preservation of various, sometimes contrasting flora elements. The barrier function of this mountain chain between the Siberian and European floras was of less importance. The montane floras of the [sector] typically show the floristic features of the Nenetsk province: European and amphi-Atlantic oceanic on one hand, and Siberian (boreal, continental Arctic, Arctic-alpine and Hypoarctic species) on the other, coexist. This subprovince includes the western foothills of the Polar Ural Mts. east of the 'Ruprecht line' (Rebristaya 1977) and is characterized by the highest richness within the province. This is due to: (1) overlapping distribution areas of western and eastern species; (2) far southward extensions of Arctic and even High Arctic species; (3) a distinct longitudinal floristic gradient (differences between the European and Asian slopes of the mountain range) and a more gradual latitudinal gradient. Several endemics arose from hybridization between Siberian and European taxa, e.g. Trollius x apertus = T. europaeus x T. asiaticus. The level of endemism is slightly higher here than in the adjacent subprovinces. Endemics of East Siberian affinity are e.g. Astragalus gorodkovii, A. igoshinae and Taraxacum platylepium." (From Yurtsev 1994.)
- Yamal-Gydan sector
"This [sector] contrasts with the previous [sector] in terms of a low floristic richness in association with various negative features of its flora: the gap in the distribution areas of many montane, predominantly East Siberian species; the absence of scores of 'eastern' (trans-Yenisey) species along with western ones (European, amphi-Atlantic, etc.) reaching the Ural Mts. Many 'western' species are confined to the lower Ob drainage up to the Taz Peninsula, and are lacking in the Gydan Peninsula; some of them are also recorded outside the Arctic from the mountains on the right bank of the Yenisey River. Most of the western elements are restricted to the southernmost areas whereas the role of the eastern counterparts increases northwards. Endemism is almost totally lacking here." (From Yurtsev 1994.)