Palearctic realm

The Palearctic or Palaearctic is one of the eight biogeographic realms of the Earth. It was first used in the 19th century, and is still in use as the basis for zoogeographic classification. The Palearctic is the largest of the eight realms. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.

The Palearctic realm

The realm consists of several ecoregions: the Euro-Siberian region; the Mediterranean Basin; the Sahara and Arabian Deserts; and Western, Central and East Asia. The Palaearctic realm also has numerous rivers and lakes, forming several freshwater ecoregions.

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]

Frontispiece to Alfred Russel Wallace's book The Geographical Distribution of Animals

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.

Major ecological regions

The Palearctic realm includes mostly boreal/subarctic-climate and temperate-climate ecoregions, which run across Eurasia from western Europe to the Bering Sea.

Euro-Siberian region
Main article: Euro-Siberian region

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 ecoregion 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.

Mediterranean Basin
Main article: Mediterranean Basin

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, or 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.

Western and Central Asia

The Caucasus mountains, which run between the Black Sea and the Caspian Sea, are a particularly rich mix of coniferous, broadleaf, and mixed forests, and include the temperate rain forests of the Euxine-Colchic deciduous forests ecoregion.

Central Asia and the Iranian plateau are home to dry steppe grasslands 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 2000–2500 m 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 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, 3050 m), northernmost Vietnam (on Fan Si Pan, 3140 m) and the high mountains of Taiwan.

Freshwater

The realm contains several important freshwater ecoregions as well, including the heavily developed rivers of Europe, the rivers of Russia, which flow into the Arctic, Baltic, Black, and Caspian seas, Siberia's Lake Baikal, the oldest and deepest lake on the planet, and Japan's ancient Lake Biwa.

Flora and fauna

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).

Megafaunal extinctions

Several large Palearctic animals became extinct from the end of the Pleistocene into historic times, including Irish elk (Megaloceros giganteus), aurochs (Bos primigenius), woolly rhinoceros (Coelodonta antiquitatis), woolly mammoth (Mammuthus primigenius), North African elephant (Loxodonta africana pharaoensis), Chinese elephant (Elephas maximus rubridens), cave bear (Ursus spelaeus), and European lion (Panthera leo europaea).

Palearctic terrestrial ecoregions
Guizhou Plateau broadleaf and mixed forests China
Yunnan Plateau subtropical evergreen forests China
Palearctic temperate broadleaf and mixed forests
Apennine deciduous montane forests Italy
Atlantic mixed forests Denmark, France, Belgium, Germany, Netherlands
Azores temperate mixed forests Portugal
Balkan mixed forests Bosnia and Herzegovina, Bulgaria, Greece, North Macedonia, Romania, Serbia, Turkey
Baltic mixed forests Sweden, Denmark, Germany, Poland
Cantabrian mixed forests Spain, Portugal
Caspian Hyrcanian mixed forests Iran, Azerbaijan
Caucasus mixed forests Georgia, Armenia, Azerbaijan, Russia, Turkey
Celtic broadleaf forests United Kingdom, Ireland
Central Anatolian deciduous forests Turkey
Central China loess plateau mixed forests China
Central European mixed forests Austria, Germany, Lithuania, Moldova, Poland, Belarus, Czech Republic
Central Korean deciduous forests North Korea, South Korea
Changbai Mountains mixed forests China, North Korea
Changjiang Plain evergreen forests China
Crimean Submediterranean forest complex Russia, Ukraine
Daba Mountains evergreen forests China
Dinaric Mountains mixed forests Albania, Bosnia and Herzegovina, Italy, Montenegro, Serbia, Slovenia, Croatia
East European forest steppe Bulgaria, Moldova, Romania, Russia, Ukraine
Eastern Anatolian deciduous forests Turkey
English Lowlands beech forests United Kingdom
Euxine-Colchic deciduous forests Bulgaria, Georgia, Turkey
Hokkaido deciduous forests Japan
Huang He Plain mixed forests China
Madeira evergreen forests Portugal
Manchurian mixed forests China, North Korea, Russia, South Korea
Nihonkai evergreen forests Japan
Nihonkai montane deciduous forests Japan
North Atlantic moist mixed forests Ireland, United Kingdom
Northeast China Plain deciduous forests China
Pannonian mixed forests Austria, Bosnia and Herzegovina, Czech Republic, Hungary, Romania, Serbia, Slovakia, Slovenia, Ukraine, Croatia
Po Basin mixed forests Italy
Pyrenees conifer and mixed forests France, Spain, Andorra
Qin Ling Mountains deciduous forests China
Rodope montane mixed forests Bulgaria, Greece, North Macedonia, Serbia
Sarmatic mixed forests Russia, Sweden, Norway, Denmark, Finland, Lithuania, Latvia, Estonia, Belarus
Sichuan Basin evergreen broadleaf forests China
South Sakhalin-Kurile mixed forests Russia
Southern Korea evergreen forests South Korea
Taiheiyo evergreen forests Japan
Taiheiyo montane deciduous forests Japan
Tarim Basin deciduous forests and steppe China
Ussuri broadleaf and mixed forests Russia
West Siberian broadleaf and mixed forests Russia
Western European broadleaf forests Switzerland, Austria, France, Germany, Czech Republic
Zagros Mountains forest steppe Iran, Iraq, Turkey
Alps conifer and mixed forests Austria, France, Germany, Italy, Slovenia, Switzerland
Altai montane forest and forest steppe China, Kazakhstan, Mongolia, Russia
Caledon conifer forests United Kingdom
Carpathian montane conifer forests Czech Republic, Poland, Romania, Slovakia, Ukraine
Da Hinggan-Dzhagdy Mountains conifer forests China, Russia
East Afghan montane conifer forests Afghanistan, Pakistan
Elburz Range forest steppe Iran
Helanshan montane conifer forests China
Hengduan Mountains subalpine conifer forests China
Hokkaido montane conifer forests Japan
Honshū alpine conifer forests Japan
Khangai Mountains conifer forests Mongolia
Mediterranean conifer and mixed forests Algeria, Morocco, Spain, Tunisia
Northeastern Himalayan subalpine conifer forests China, India, Bhutan
Northern Anatolian conifer and deciduous forests Turkey
Nujiang Langcang Gorge alpine conifer and mixed forests China
Qilian Mountains conifer forests China
Qionglai-Minshan conifer forests China
Sayan montane conifer forests Mongolia, Russia
Scandinavian coastal conifer forests Norway
Tian Shan montane conifer forests China, Kazakhstan, Kyrgyzstan
East Siberian taiga Russia
Iceland boreal birch forests and alpine tundra Iceland
Kamchatka-Kurile meadows and sparse forests Russia
Kamchatka-Kurile taiga Russia
Northeast Siberian taiga Russia
Okhotsk-Manchurian taiga Russia
Sakhalin Island taiga Russia
Scandinavian and Russian taiga Finland, Norway, Russia, Sweden
Trans-Baikal conifer forests Mongolia, Russia
Urals montane tundra and taiga Russia
West Siberian taiga Russia
Al-Hajar foothill xeric woodlands and shrublands Oman, United Arab Emirates
Al-Hajar montane woodlands and shrublands Oman, United Arab Emirates
Alai-Western Tian Shan steppe Kazakhstan, Tajikistan, Uzbekistan
Altai steppe and semi-desert Kazakhstan
Central Anatolian steppe Turkey
Daurian forest steppe China, Mongolia, Russia
Eastern Anatolian montane steppe Armenia, Iran, Turkey
Emin Valley steppe China, Kazakhstan
Faroe Islands boreal grasslands Faroe Islands, Denmark
Gissaro-Alai open woodlands Kyrgyzstan, Tajikistan, Uzbekistan
Kazakh forest steppe Kazakhstan, Russia
Kazakh steppe Kazakhstan, Russia
Kazakh Uplands Kazakhstan
Mongolian-Manchurian grassland China, Mongolia, Russia
Pontic steppe Kazakhstan, Moldova, Romania, Russia, Ukraine, Bulgaria
Sayan Intermontane steppe Russia
Selenge-Orkhon forest steppe Mongolia, Russia
South Siberian forest steppe Russia
Syrian xeric grasslands and shrublands Iraq, Jordan, Syria
Tian Shan foothill arid steppe China, Kazakhstan, Kyrgyzstan
Amur meadow steppe China, Russia
Bohai Sea saline meadow China
Nenjiang River grassland China
Nile Delta flooded savanna Egypt
Saharan halophytics Algeria, Egypt, Mauritania, Tunisia, Western Sahara
Tigris–Euphrates alluvial salt marsh Iraq, Iran
Ussuri-Wusuli meadow and forest meadow China, Russia
Yellow Sea saline meadow China
Altai alpine meadow and tundra China, Kazakhstan, Mongolia, Russia
Central Tibetan Plateau alpine steppe China
Eastern Himalayan alpine shrub and meadows Bhutan, Myanmar, China, India, Nepal
Ghorat-Hazarajat alpine meadow Afghanistan
Hindu Kush alpine meadow Afghanistan, Pakistan
Karakoram-West Tibetan Plateau alpine steppe Afghanistan, China, India, Pakistan
Khangai Mountains alpine meadow Mongolia
Kopet Dag woodlands and forest steppe Iran, Turkmenistan
Kuhrud-Kohbanan Mountains forest steppe Iran
Mediterranean High Atlas juniper steppe Morocco
North Tibetan Plateau-Kunlun Mountains alpine desert China
Northwestern Himalayan alpine shrub and meadows China, India, Pakistan
Ordos Plateau steppe China
Pamir alpine desert and tundra Afghanistan, China, Kyrgyzstan, Tajikistan
Qilian Mountains subalpine meadows China
Sayan Alpine meadows and tundra Mongolia, Russia
Southeast Tibet shrub and meadows China
Sulaiman Range alpine meadows Afghanistan, Pakistan
Tian Shan montane steppe and meadows China, Kazakhstan, Kyrgyzstan
Tibetan Plateau alpine shrublands and meadows China
Western Himalayan alpine shrub and meadows India, Nepal
Yarlung Zambo arid steppe China
Arctic desert Russia, Svalbard (Norway)
Bering tundra Russia
Cherskii-Kolyma mountain tundra Russia
Chukchi Peninsula tundra Russia
Kamchatka Mountain tundra and forest tundra Russia
Kola Peninsula tundra Norway, Russia
Northeast Siberian coastal tundra Russia
Northwest Russian-Novaya Zemlya tundra Russia
New Siberian Islands arctic desert Russia
Scandinavian montane birch forest and grasslands Finland, Norway, Sweden
Taimyr-Central Siberian tundra Russia
Trans-Baikal Bald Mountain tundra Russia
Wrangel Island arctic desert Russia
Yamalagydanskaja tundra Russia
Aegean and Western Turkey sclerophyllous and mixed forests Greece, North Macedonia, Turkey
Anatolian conifer and deciduous mixed forests Turkey
Canary Islands dry woodlands and forests Spain
Corsican montane broadleaf and mixed forests France
Crete Mediterranean forests Greece
Cyprus Mediterranean forests Cyprus
Eastern Mediterranean conifer-sclerophyllous-broadleaf forests Israel, Jordan, Lebanon, Syria, Turkey
Iberian conifer forests Spain
Iberian sclerophyllous and semi-deciduous forests Portugal, Spain
Illyrian deciduous forests Albania, Bosnia and Herzegovina, Croatia, Greece, Italy, Slovenia
Italian sclerophyllous and semi-deciduous forests France, Italy
Mediterranean acacia-argania dry woodlands and succulent thickets Morocco, Canary Islands (Spain)
Mediterranean dry woodlands and steppe Algeria, Egypt, Libya, Morocco, Tunisia
Mediterranean woodlands and forests Algeria, Libya, Morocco, Tunisia
Northeastern Spain and Southern France Mediterranean forests France, Monaco, Spain
Northwest Iberian montane forests Portugal, Spain
Pindus Mountains mixed forests Albania, Greece, North Macedonia
South Apennine mixed montane forests Italy
Southeastern Iberian shrubs and woodlands Spain
Southern Anatolian montane conifer and deciduous forests Israel, Jordan, Lebanon, Syria, Turkey
Southwest Iberian Mediterranean sclerophyllous and mixed forests Portugal, Spain
Tyrrhenian-Adriatic sclerophyllous and mixed forests Croatia, France, Italy, Malta
Palearctic deserts and xeric shrublands[2]
Afghan Mountains semi-desert Afghanistan
Alashan Plateau semi-desert China, Mongolia
Arabian desert Egypt, Israel, Iraq, Kuwait, Palestine, Saudi Arabia, Yemen
Arabian sand desert Oman, Saudi Arabia, United Arab Emirates, Yemen
Atlantic coastal desert Mauritania, Western Sahara
Azerbaijan shrub desert and steppe Azerbaijan, Georgia, Iran
Badkhiz-Karabil semi-desert Afghanistan, Iran, Tajikistan, Turkmenistan, Uzbekistan
Baluchistan xeric woodlands Afghanistan, Pakistan
Caspian lowland desert Iran, Kazakhstan, Russia, Turkmenistan
Central Afghan Mountains xeric woodlands Afghanistan
Central Asian northern desert Kazakhstan, Uzbekistan
Central Asian riparian woodlands Kazakhstan, Turkmenistan, Uzbekistan
Central Asian southern desert Kazakhstan, Turkmenistan, Uzbekistan
Central Persian desert basins Afghanistan, Iran
East Arabian fog shrublands and sand desert Oman
East Sahara desert Algeria, Chad, Egypt, Libya, Niger, Sudan
Eastern Gobi desert steppe China, Mongolia
Gobi Lakes Valley desert steppe Mongolia
Great Lakes Basin desert steppe Mongolia, Russia
Junggar Basin semi-desert China, Mongolia
Kazakh semi-desert Kazakhstan
Kopet Dag semi-desert Iran, Turkmenistan
Mesopotamian shrub desert Iraq, Iran, Israel, Jordan, Syria
North Arabian desert Iraq, Jordan, Saudi Arabia
North Saharan steppe and woodlands Algeria, Egypt, Libya, Mauritania, Morocco, Tunisia, Western Sahara
Paropamisus xeric woodlands Afghanistan
Persian Gulf desert and semi-desert (or Arabian-Persian Gulf desert and semi-desert) Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates
Qaidam Basin semi-desert China
Red Sea coastal desert Egypt, Sudan
Red Sea Nubo-Sindian tropical desert and semi-desert (or Red Sea-Arabian desert shrublands) Egypt, Jordan, Oman, Saudi Arabia, Yemen
Rigestan-North Pakistan sandy desert Afghanistan, Iran, Pakistan
Sahara desert Algeria, Chad, Egypt, Libya, Mali, Niger, Sudan, Western Sahara
South Arabian plains and plateau desert Oman, Yemen
South Iran Nubo-Sindian desert and semi-desert Iran, Iraq, Pakistan
South Saharan steppe and woodlands (or South Sahara desert) Algeria, Chad, Mali, Mauritania, Niger, Sudan
Taklimakan desert China
Tibesti-Jebel Uweinat montane xeric woodlands Chad, Egypt, Libya, Sudan
West Sahara desert Algeria, Libya, Mauritania
West Saharan montane xeric woodlands Algeria, Mali, Mauritania, Niger
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See also

References
  1. Sclater, Philip Lutley (1858). "On the general geographical distribution of the members of the class Aves". Zoological Journal of the Linnean Society. 2 (7): 130–145. doi:10.1111/j.1096-3642.1858.tb02549.x.
  2. 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

General references
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