Circumpolar Arctic Floristic Provinces - Beringian Group


West Siberia - East Siberia - Beringia - Canada - North Atlantic

Circumpolar Arctic Floristic Provinces - Beringian Group

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All of Arctic Alaska is within the Beringian group of floristic sectors. The term "Beringia" was coined by Eric Hultén to describe the vast region centered on the Bering Strait and extending from the Kolyma River in the west to the Mackenzie River in the Northwest Territories. During the Pleistocene glacial intervals, sea level was as much as 100 m lower than present because of large amounts of water locked up in continental glaciers. This resulted in the large land mass connecting North America with Asia shown in Fig. 1.

Hultén recognized that Beringia was the center of distribution of many plant species that evolved here while most of northern North America was covered with ice. Yurtsev (1994) described the Chukotka and Alaska provinces within in the Beringia region (which he calls the Beringian sector). The PAF project combines Yurtsev's Chukotka and Alaska provinces into a single Beringia floristic group as originally suggested by Hultén (1937).

Elvebakk et al. (1999) characterize the Beringia group: "This is a highly diverse and floristically rich group of four to six regions [sectors]…, the number depending on some decisions still to be made. The importance of the group is that it contains all the important areas assumed to have been unglaciated through all or large parts of Quaternary times, including the islands in the shelf areas now submerged. On the Asiatic side are two undisputed regions, West Chukotka along the East Siberian Sea, including Wrangel Island, and East Chukotka facing the Bering Strait and Sea, the latter region with the strongest Beringian elements on the Asiatic side. Yurtsev also proposes a South Chukotka region on both sides of the Anadyr Basin, based on a floristic element connecting it to the more southern mountains and the Koryak Coast. An alternative proposal is to unite this with West Chukotka as it is a small area with insufficient characterization. Another option is to split it into the oceanic and continental parts to be assigned to the West and East Chukotka correspondingly. On the North American side are recognized the Beringian Alaska region facing the Bering Strait and Sea, with the strongest Beringian elements on the American side, and the North Alaska region of the Brooks Range and the northern coast, also extending into Canada. The eastern delimitation of North Alaska is disputed. Yurtsev proposes to draw the line west of Mackenzie River whereas others argue for including parts of the coast east of Mackenzie and western parts of Banks Isl. and Victoria Isl. in the region. The reason is mainly that parts of these islands and the mainland have been unglaciated and have subendemic plants in common with Beringian regions. The decision will depend on how the remaining of the Canadian Arctic will be subdivided [see Canada group]. Yurtsev proposes a separate North Beringian Islands region, which includes Big Diomede Island (Russian), Little Diomede Island, St. Lawrence Island, and St. Matthew Island (all North American). This region is mainly negatively characterized, except for a very few Pacific oceanic species more frequent here than on the mainlands. The islands would have been a natural part of a larger region including Pribyloff Islands, the Aleutian Islands and the Commodore Islands, but we have decided to exclude these from the Arctic. The alternative proposal is to join the islands with the neighboring regions: Big Diomede with East Chukotka, the others with Beringian Alaska." (From Elvebakk et al. 1999).