Eastern Asiatic Region

The Eastern Asiatic Region (also known as Oriasiaticum, Sino-Japanese Region, East Asian Region, Temperate Eastern Region) is the richest floristic region within the Holarctic Kingdom and situated in temperate East Asia. It has been recognized as a natural floristic area since 1872 August Grisebach's volume Die Vegetation der Erde and later delineated by such geobotanists as Ludwig Diels, Adolf Engler (as Temperate Eastern region), Ronald Good (as Sino-Japanese Region) and Armen Takhtajan.

The Eastern Asiatic Region is dominated by very old lineages of gymnosperms and woody plant families and is thought to be the cradle of the Holarctic flora. Moreover, this floristic region wasn't significantly glaciated in the Pleistocene, and many relict Tertiary genera (such as Metasequoia glyptostroboides, ancestors of which were once common throughout the Northern Hemisphere up to subpolar latitudes) found refuge here.

Sichuan forest
A forest in Sichuan
Lushan bamboo forest
Bamboo forest in Lushan, China

Endemic flora

The Eastern Asiatic Region endemic flora is characterized by:

Endemic families

Endemic genera

Approximately eight other families are shared with tropical Southeast Asia (Nageiaceae, Rhodoleiaceae, Daphniphyllaceae, Pentaphyllaceae, Duabangaceae, Mastixiaceae, Pentaphragmataceae, Lowiaceae). As has long been noted, many relict genera occurring in East Asia, such as Liriodendron and Hamamelis, are shared with temperate North America, especially the North American Atlantic Region.

Adjacent Regions

The Eastern Asiatic Region is bordered by the Circumboreal Region of the Holarctic Kingdom in the north, the Irano-Turanian Region of the same kingdom in the west and Indian, Indochinese and Malesian Regions of the Paleotropical Kingdom in the south. It comprises the southern part of the Russian Far East, southern part of Sakhalin, Manchuria, Korea, Japan, Taiwan, relatively humid eastern part of the mainland China from Manchuria and the seashore to Eastern Himalaya and Kali Gandaki Valley in Nepal, including Sikkim, northern Burma and northernmost Vietnam (parts of Tonkin).

Subdivisions

According to a version of Takhtajan's classification, the Eastern Asiatic Region is further subdivided into 13 provinces; however, the number and delimitation of the southern provinces is disputed and varies even across Takhtajan's work.

  • Manchurian Province
two endemic genera (Microbiota, Omphalothrix), many endemic species (including Abies holophylla, Picea koraiensis, Ulmus macrocarpa, Crataegus pinnatifida, Vitis amurensis)
  • Sakhalin-Hokkaido Province
one endemic genus (Miyakea), some endemic species (including Abies sachalinensis, Fragaria yezoensis)
  • Japan-Korean Province
  • Ryukyu Province[1]
  • Volcanic-Bonin Province
  • Taiwanese Province
  • Northern Chinese Province
  • Central Chinese Province
  • Southeastern Chinese Province
  • Sikang-Yuennan Province
  • Northern Burmese Province
  • Eastern Himalayan Province
  • Khasi-Manipur Province

References

  1. ^ Nakamura, K., et al. (2009). Geohistorical and current environmental influences on floristic differentiation in the Ryukyu Archipelago, Japan. Journal of Biogeography 36:919–928. DOI: 10.1111/j.1365-2699.2008.02057.x

Cheng-yih Wu. Delineation and Unique Features of the Sino-Japanese Floristic Region. David E. Boufford and Hideaki Ohba (eds.), University of Tokyo Bulletin 37: Sino-Japanese Flora — Its Characteristics and Diversification. Tokyo: University of Tokyo, 1998.

Actinidia kolomikta

Actinidia kolomikta, commonly known as variegated-leaf hardy kiwi, is a species of flowering plant in the family Actinidiaceae, native to temperate mixed forests of the Russian Far East, Korea, Japan and China (Eastern Asiatic Region).

Boreal Kingdom

The Boreal Kingdom or Holarctic Kingdom (Holarctis) is a floristic kingdom identified by botanist Ronald Good (and later by Armen Takhtajan), which includes the temperate to Arctic portions of North America and Eurasia. Its flora is inherited from the ancient supercontinent of Laurasia. However, parts of the floristic kingdom (and most of its Circumboreal Region) were glaciated during the Pleistocene and as a consequence have a very young flora. Cenozoic relicts found refuge in the southern and mountainous parts of the kingdom, especially in the Eastern Asiatic Region and southern North American Atlantic Region.

Good noted that many plant species of temperate North America and Eurasia were very closely related, despite their separation by the Atlantic Ocean and the Bering Strait.

Millions of years ago, before the opening of the Atlantic Ocean, North America and Eurasia were joined as a single continent, Laurasia. After the opening of the Atlantic, the continents were connected to one another periodically via land bridges linking Alaska and Siberia. Until a few million years ago, the global climate was warmer than at present, especially at higher latitudes, and many temperate climate species were distributed across North America and Eurasia via Alaska and Siberia. The sharply cooler climate of the past few million years eliminated a temperate-zone connection between North America and Eurasia, but common Laurasian origins and a long history of temperate-climate land bridges account for the botanical similarities between the temperate floras on the two continents.

A floristic kingdom is the botanical analogue to an ecozone, which takes into account the distribution of animal as well as plant species. Many biogeographers distinguish the Boreal Kingdom as comprising two ecozones, the Nearctic (North America) and Palearctic (North Africa and Eurasia). Others, based on the distribution of related plant and animal families, include the Palearctic and Nearctic in a single Holarctic ecozone, which corresponds to Good's Boreal Kingdom.

Juglans mandshurica

Juglans mandshurica, the Manchurian walnut, is a deciduous tree of the genus Juglans (section Cardiocaryon), native to the Eastern Asiatic Region (China, Russian Far East, North Korea and South Korea). It grows to about 25 m.

The leaves are alternate, 40–90 cm long, odd-pinnate, with 7–19 leaflets, 6–17 cm long and 2–7.5 cm broad (margin serrate or serrulate, apex acuminate). The male flowers are in drooping catkins 9–40 cm long, the wind-pollinated female flowers (April–May) are terminal, in spikes of 4 to 10, ripening in August–October into nuts, 3-7.5 × 3–5 cm, with densely glandular pubescent green husk and very thick shell.

The tree is exceptionally hardy (down to at least -45 °C), has a relatively short vegetation period compared to other walnuts, grows rapidly and is cultivated as an ornamental in colder temperate regions all over the Northern Hemisphere. (For example, it has been found to grow satisfactorily in Edmonton, Alberta, Canada.) The kernels of the nuts are edible, but small and difficult to extract. The timber is in use, but less valuable than that of English walnut or black walnut.

The Manchurian walnut contains and exudes much lesser quantities of allelopathic compounds (such as juglone) than other popular Juglans species and usually causes few significant allelopathic effects in cultivation.

Juglans cathayensis, characterized by tomentose leaflets, producing more flowers per spike and growing south of the Yellow River, was sometimes recognized as a species separate from J. mandshurica.

The Japanese walnut Japanese: 鬼胡桃(oni-gurumi) is listed by some authorities as Juglans mandshurica var. sachalinensis (syn. "Juglans ailantifolia")

North American Atlantic Region

North American Atlantic Region is a floristic region within the Holarctic Kingdom identified by Armen Takhtajan and Robert F. Thorne, spanning from the Atlantic and Gulf coasts to the Great Plains and comprising a major part of the United States and southeastern portions of Canada. It is bordered by the Circumboreal floristic region in the north, by the Rocky Mountain and Madrean floristic regions in the west and by the Caribbean floristic region of the Neotropical Kingdom in the south of Florida. The flora of the region comprises two endemic monotypic families, Hydrastidaceae and Leitneriaceae, and is characterized by about a hundred of endemic genera (such as Sanguinaria, Leavenworthia, Gillenia, Neviusia, Dionaea, Yeatesia, Pleea). The degree of species endemism is very high, many species are Tertiary relicts, which survived the Wisconsin glaciation and are now concentrated in the Appalachians (esp. Blue Ridge Mountains) and the Ozarks. A number of genera (Sarracenia, Uvularia etc.) are shared only with the Canadian floristic province of the Circumboreal region. Moreover, as has long been noted (e.g. by Joseph Gerhard Zuccarini and especially by Asa Gray), a large number of relict genera (Liriodendron, Hamamelis, Stewartia etc.) are shared with the relatively distant Eastern Asiatic Region (comprising Japan, Korea, and the east of China) and sometimes Southeast Asia. R. F. Thorne counted at least 74 genera restricted to eastern North America and Asia (mostly eastern and southeastern Asia). The fossil record indicates that during the Tertiary period a warm temperate zone extended across much of the Northern Hemisphere, linking America to Asia.

Phytochorion

A phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phytochoria do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both regions overlap. The region of overlap is called a vegetation tension zone.

In traditional schemes, areas in phytogeography are classified hierarchically, according to the presence of endemic families, genera or species, e.g., in floral (or floristic, phytogeographic) zones and regions, or also in kingdoms, regions and provinces, sometimes including the categories empire and domain. However, some authors prefer not to rank areas, referring to them simply as "areas", "regions" (in a non hierarchical sense) or "phytochoria".Systems used to classify vegetation can be divided in two major groups: those that use physiognomic-environmental parameters and characteristics and those that are based on floristic (i.e. shared genera and species) relationships. Phytochoria are defined by their plant taxonomic composition, while other schemes of regionalization (e.g., vegetation type, physiognomy, plant formations, biomes) may variably take in account, depending on the author, the apparent characteristics of a community (the dominant life-form), environment characteristics, the fauna associated, anthropic factors or political-conservationist issues.

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