The Arctic has a relatively consistent core ofplant species that occur throughout the circumpolar region, but there is also considerable east to west variation in regional floras, particularly in the southern bioclimate subzones. These differences are due to factors such as different histories related to glaciations, land bridges, and north-south trending mountain ranges that have influenced the exchange of species between parts of the Arctic. Floristic provinces are used to explain the east-west variation in species distribution in the Arctic. Alaska is included within the Beringian Floristic Province, and includes three of the 23 circumpolar Sub-Provinces: North Beringian Islands, Beringian Alaska, and Northern Alaska (Yurtsev 1994, Walker 2005).
Floristic provinces were mapped from the Panarctic Flora Initiative (Elvebakk et al. 1999), based largely on Yurtsev (1994). The boundaries were then adjusted to follow vegetation polygon boundaries. The vegetation polygons are drawn at a much finer resolution than the floristic province boundaries, so little information was lost in this process.
Elvebakk, A. 1999. Bioclimate delimitation and subdivisions of the Arctic. Pages 81-112 in I. Nordal and V. Y. Razzhivin, editors. The Species Concept in the High North - A Panarctic Flora Initiative. The Norwegian Academy of Science and Letters, Oslo.
Walker, D. A., M. K. Raynolds, F. J. A. Daniels, E. Einarsson, A. Elvebakk, W. A. Gould, A. E. Katenin, S. S. Kholod, C. J. Markon, E. S. Melnikov, N. G. Moskalenko, S. S. Talbot, B. A. Yurtsev, and CAVM Team. 2005. The Circumpolar Arctic Vegetation Map. Journal of Vegetation Science 16:267-282.
Yurtsev, B. A. 1994. Floristic divisions of the Arctic. Journal of Vegetation Science 5:765-776.