The term 'Palearctic' was first used in the 19th century, and is still in use as the basis for
zoogeographic classification.
History
In an 1858 paper for the Proceedings of the
Linnean Society, British zoologist
Philip Sclater first identified six terrestrial zoogeographic realms of the world: Palaearctic, Aethiopian/
Afrotropic,
Indian/
Indomalayan,
Australasian,
Nearctic, and
Neotropical. The six indicated general groupings of fauna, based on shared biogeography and large-scale geographic barriers to migration.[1]
Alfred Wallace adopted Sclater's scheme for his book The Geographical Distribution of Animals, published in 1876. This is the same scheme that persists today, with relatively minor revisions, and the addition of two more realms:
Oceania and the
Antarctic realm.
The boreal and temperate Euro-Siberian region is the Palearctic's largest
biogeographic region, which transitions from
tundra in the northern reaches of
Russia and
Scandinavia to the vast
taiga, the boreal coniferous forests which run across the continent. South of the taiga are a belt of
temperate broadleaf and mixed forests and
temperate coniferous forests. This vast Euro-Siberian region is characterized by many shared plant and animal species, and has many affinities with the temperate and boreal regions of the
Nearctic realm of
North America. Eurasia and North America were often connected by the
Bering land bridge, and have very similar
mammal and bird fauna, with many Eurasian species having moved into North America, and fewer North American species having moved into Eurasia. Many zoologists consider the Palearctic and Nearctic to be a single
Holarctic realm. The Palearctic and Nearctic also share many plant species, which botanists call the
Arcto-Tertiary Geoflora.
The lands bordering the
Mediterranean Sea in southern Europe, north Africa, and western Asia are home to the
Mediterranean Basin ecoregions, which together constitute the world's largest and most diverse
mediterranean climate region of the world, with generally mild, rainy winters and hot, dry summers. The Mediterranean basin's mosaic of
Mediterranean forests, woodlands, and scrub are home to 13,000
endemic species. The Mediterranean basin is also one of the world's most endangered biogeographic regions; only 4% of the region's original vegetation remains, and human activities, including
overgrazing,
deforestation, and conversion of lands for pasture, agriculture, and urbanization, have degraded much of the region. Formerly the region was mostly covered with forests and woodlands, but heavy human use has reduced much of the region to the
sclerophyll shrublands known as
chaparral,
matorral,
maquis, or
garrigue.
Conservation International has designated the Mediterranean basin as one of the world's
biodiversity hotspots.
Sahara and Arabian deserts
A great belt of deserts, including the
Atlantic coastal desert,
Sahara desert, and
Arabian desert, separates the Palearctic and
Afrotropic ecoregions. This scheme includes these desert ecoregions in the palearctic realm; other biogeographers identify the realm boundary as the transition zone between the desert ecoregions and the Mediterranean basin ecoregions to the north, which places the deserts in the Afrotropic, while others place the boundary through the middle of the desert.
Central Asia and the
Iranian plateau are home to dry
steppegrasslands and
desert basins, with montane forests, woodlands, and grasslands in the region's high mountains and plateaux. In southern Asia the boundary of the Palearctic is largely altitudinal. The middle altitude foothills of the
Himalaya between about 2,000–2,500 m (6,600–8,200 ft) form the boundary between the Palearctic and
Indomalaya ecoregions.
East Asia
China,
Korea and
Japan are more humid and temperate than adjacent
Siberia and Central Asia, and are home to rich temperate coniferous, broadleaf, and mixed forests, which are now mostly limited to mountainous areas, as the densely populated lowlands and river basins have been converted to intensive agricultural and urban use. East Asia was not much affected by glaciation in the
ice ages, and retained 96 percent of
Pliocene[citation needed] tree genera, while Europe retained only 27 percent. In the subtropical region of southern China and southern edge of the Himalayas, the Palearctic temperate forests transition to the subtropical and tropical forests of
Indomalaya, creating a rich and diverse mix of plant and animal species. The
mountains of southwest China are also designated as a
biodiversity hotspot. In Southeastern Asia, high
mountain ranges form tongues of Palearctic flora and fauna in northern
Indochina and southern
China. Isolated small outposts (
sky islands) occur as far south as central Myanmar (on
Nat Ma Taung, 3,050 m; 10,010 ft), northernmost
Vietnam (on
Fan Si Pan, 3,140 m; 10,300 ft) and the high mountains of
Taiwan.
One bird family, the
accentors (Prunellidae), is endemic to the Palearctic region. The
Holarctic has four other endemic bird families: the divers or
loons (Gaviidae),
grouse (Tetraoninae),
auks (Alcidae), and
waxwings (Bombycillidae).
There are no endemic
mammal orders in the region, but several families are endemic: Calomyscidae (
mouse-like hamsters),
Prolagidae, and Ailuridae (
red pandas). Several mammal species originated in the Palearctic and spread to the Nearctic during
the Ice Age, including the
brown bear (Ursus arctos, known in North America as the grizzly),
red deer (Cervus elaphus) in Europe and the closely related
elk (Cervus canadensis) in far eastern Siberia,
American bison (Bison bison), and
reindeer (Rangifer tarandus, known in North America as the
caribou).
^Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545
[1]
General references
Amorosi, T. "Contributions to the zooarchaeology of Iceland: some preliminary notes" in The Anthropology of Iceland (eds. E.P. Durrenberger & G. Pálsson). Iowa City:
University of Iowa Press, pp. 203–227, 1989.
Buckland, P.C., et al. "Holt in Eyjafjasveit, Iceland: a paleoecological study of the impact of Landnám" in Acta Archaeologica 61: pp. 252–271. 1991.
Edmund Burke III, "The Transformation of the middle Eastern Environment, 1500 B.C.E.–2000 C.E." in The Environment and World History, ed. Edmund Burke III and Kenneth Pomeranz. Berkeley: University of California Press. 2009, 82–84.