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Floristic Interrelations of the Arctic and Alpine Tundras in Eastern Asia and Western North America

Qian Hong   

  • Received:1900-01-01 Revised:1900-01-01 Online:1993-01-10 Published:1993-01-10
  • Contact: Qian Hong

Abstract:

Tundra should be designated as the vegetation in the Arctic treeless
area beyond treeline latitudinally, and as the vegetation in alpine treeless areas
above treeline which are greatly similar to the Arctic one not only in environment
but also in floristic composition and phyto-community. Tundras are limited to the
Northern Hemisphere, and is mainly distributed in the circumpolar region (over
95% out of the total). Only a small part of tundra vegetations is scattered in the
alpine treeless areas in the middle latitudinal region of the Northern Hemisphere,
and is called the alpine tundra and/or mountain tundra. The alpine tundra is
greatly similar to the Arctic tundra not only in environment features and vegeta-
tion appearance, but in flora as well.  Actually,  nowaday alpine tundra is
directly developed from the remnant segments of the Arctic tundra which migrated
southwards to the middle latitudinal region of the Northern Hemisphere in the gla-
cial period of the last Ice-age in the Pleistocene, and later moved up to the alpine
areas in the Holocene. The alpine tundras of the Changbai Mountain and Rocky
Mountains (middle section)are located on the southern fringes of the tundras in
Eastern Asia and Western North America respectively.
    By means of comparative analyses of the vascular floras of the Chukotka (in
NE.  Asia)  Arctic  tundra  and Alaska (in  NW.  America) Arctic tundra
(transberingian comparison), the Changbai Mountain (in E. Asia) alpine tundra
and Rocky Mountains(in W.  North America)  alpine tundra( transpacific
comparison), and the alpine tundras and the arctic tundras in E. Asia and W.
North America, the results show as follows:
    (1) Because of the fact that Chukotka and Alaska not only share 411
species (making up 83% of the former total species and 72% of the latter total
species),  but  also  have many  endemic species with  a 'Chukotka-Alaska'
discontinuous distribution pattern, while there are only 268 species shared by the
Arctic tundras of Chukotka and East Siberia and 332 species shared by the Arctic
tundras of Alaska and Canada, it seems reasonable to consider the Arctic tundras
of Chukotka and Alaska as one floristic province-the Beringian Floristic
Province. The existence of the Beringian Floristic Province could at least be
traced back to 18,000 B. P. in the Pleistocene.
    (2) There is a close relationship between the alpine tundras of Eastern Asia
and Western North America. This relationship was built up by means of the
Bering Land Bridge in Ice-age.
     (3) In Eastern Asia, 42% species out of the total in the alpine tundra of
Changbai Mountains are shared with the Arctic tundra of Chukotka; and in
Western North America, 48.9% species out of the total in the alpine tundra of
Rocky Mountains (middle section) are shared with the Arctic tundra of Alaska.
Therefore, the floristic relationships of the alpine tundras and the Arctic tundras
(especially Beringian Arctic tundra) in Eastern Asia and Western North America
are very close.
     (4) The Bering Land  Bridge in the Pleistocene became an exchange
passageway of the floras between Eastern Asia and Western North America proba-
bly only for their Arctic tundra species, but not for the forest tree species nearby
the Arctic treeline.
Key words  Floristics; Arctic tundra; Alpine tundra; Chukotka; Alaska; Changbai Mountains; Rocky Mountains; Eastern Asia; Western North America

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