Phytochorion

A Phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phtyochoria 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.

Explanation

Several systems of classifying geographic areas where plants grow have been devised. Most systems are organized hierarchically, with the largest units subdivided into smaller geographic areas, which are made up of smaller floristic communities, and so on. phtyochoria are defined as areas possessing a large number of endemic taxons. Floristic kingdoms are characterized by a high degree of family endemism, floristic regions – by a high degree of generic endemism, floristic provinces – by a high degree of species endemism. Systems of phytochoria have both significant similarities and differences with zoogeographic provinces, which follow the composition of mammal families, and with biogeographical provinces or terrestrial ecoregions, which take into account both plant and animal species.

The term "phytochorion" is especially associated with the classifications according to the methodology of Josias Braun-Blanquet , which is tied to the presence or absence of particular species. [ [http://www.ngo.grida.no/soesa/nsoer/Data/vegrsa/vegglos.htm glossary] from cite book | title = Vegetation of South Africa, Lesotho and Swaziland: A companion to the Vegetation Map of South Africa, Lesotho and Swaziland | author = Edited by A. Barrie Low and A. (Tony) G. Rebelo from contributions by George J. Bredenkamp, J. Ed Granger, M. Timm Hoffman, Roy A. Lubke, Bruce Mckenzie, A. (Tony) Rebelo, & Noel van Rooyen | publisher = Department of Environmental Affairs and Tourism, Pretoria | date = February 1998]

Taxonomic databases tend to be organized in ways which approximate floristic provinces, but which are more closely aligned to political boundaries, for example according to the World Geographical Scheme for Recording Plant Distributions.

Floristic kingdoms

Botanist Ronald Good identified six floristic kingdoms (Boreal, Neotropical, Paleotropical, South African, Australian, and Antarctic), the largest natural units he determined for flowering plants. Good's six kingdoms are subdivided into smaller units, called provinces. The Paleotropical kingdom is divided into three subkingdoms, which are each subdivided into floristic provinces. Each of the other five kingdoms are subdivided directly into provinces. There are a total of 37 floristic provinces. Almost all provinces are further subdivided into floristic regions.

Armen Takhtajan, in a widely used scheme that builds on Good's work, identified thirty-five floristic regions, each of which is subdivided into floristic provinces, of which there are 152 in all.

Takhtajan's floristic provinces

Holarctic Kingdom

I. Circumboreal Region

:1 :2 Atlantic Europe:3 Central Europe:4 Illyria or Balkan:5 Pontus Euxinus:6 Caucasus:7 Eastern Europe:8 Northern Europe:9 Western Siberia:10 Altai-Sayan:11 Central Siberia:12 Transbaikalia:13 Northeastern Siberia:14 Okhotsk-Kamchatka:15 Canada incl. Great Lakes

II. Eastern Asiatic Region

:16 Manchuria:17 Sakhalin-Hokkaidō:18 Japan-Korea:19 Volcano-Bonin:20 Ryūkyū or Tokara-Okinawa:21 Taiwan:22 Northern China:23 Central China:24 Southeastern China:25 Sikang-Yuennan:26 Northern Burma:27 Eastern Himalaya:28 Khasi-Manipur

III. North American Atlantic Region

:29 Appalachian Province (forested areas extending east to include the piedmont and west to the start of the prairies):30 Atlantic and Gulf Coastal Plain:31 North American Prairies

IV. Rocky Mountain Region

:32 Vancouver:33 Rocky Mountains

=V. Macaronesian Region=

:34 Azores:35 Madeira:36 Canaries:37 Cape Verde

VI. Mediterranean Region

:38 Southern Morocco:39 Southwestern Mediterranean:40 South Mediterranean:41 Iberia:42 Baleares:43 Liguria-Tyrrhenia:44 Adriatic:45 East Mediterranean:46 Crimea-Novorossijsk

VII. Saharo-Arabian Region

:47 Sahara:48 Egypt-Arabia

VIII. Irano-Turanian Region

:49 Mesopotamia:50 Central Anatolia:51 Armenia-Iran:52 Hyrcania:53 Turania or Aralo-Caspia:54 Turkestan:55 Northern Baluchistan:56 Western Himalaya:57 Central Tien Shan:58 Dzungaria-Tien Shan:59 Mongolia:60 Tibet

IX. Madrean Region

:61 Great Basin:62 California:63 Sonora:64 Mexican Highlands

Paleotropical Kingdom

X. Guineo-Congolian Region

:65 Upper Guinea:66 Nigeria-Cameroon:67 Congo

XI. Usambara-Zululand Region

:68 Zanzibar-Inhambane:69 Tongoland-Pondoland

XII. Sudano-Zambezian Region

:70 Zambezi:71 Sahel:72 Sudan:73 Somalia-Ethiopia:74 South Arabia:75 Socotra:76 Oman:77 South Iran:78 Sindia

XIII. Karoo-Namib Region

:79 Namibia:80 Namaland:81 Western Cape:82 Karoo

XIV. St.Helena and Ascension Region

:83 St. Helena and Ascension

XV. Madagascan Region

:84 Eastern Madagascar:85 Western Madagascar:86 Southern and Southwestern Madagascar:87 Comoro:88 Mascarenes:89 Seychelles

XVI. Indian Region

:90 Ceylon (Sri Lanka):91 Malabar:92 Deccan:93 Upper Gangetic Plain:94 Bengal

XVII. Indochinese Region

:95 South Burma:96 Andamans:97 South China:98 Thailand:99 North Indochina:100 Annam:101 South Indochina

=XVIII. Malesian Region=

:102 Malaya:103 Borneo:104 Philippines:105 Sumatra:106 South Malesia:107 Celebes:108 Moluccas and West New Guinea:109 Papua:110 Bismarck Archipelago

XIX. Fijian Region

:111 New Hebrides:112 Fiji

XX. Polynesian Region

:113 Micronesia:114 Polynesia

XXI. Hawaiian Region

:115 Hawaii

XXII. Neocaledonian Region

:116 New Caledonia

Neotropical Kingdom

XXIII. Caribbean Region

:117 Central America:118 West Indies:119 Galápagos Islands

XXIV. Region of the Guayana Highlands

:120 Guayana

XXV. Amazonian Region

:121 Amazonia:122 Llanos

XXVI. Brazilian Region

:123 Caatinga:124 Central Brazilian Uplands:125 Chaco:126 Atlantic Brazil:127 Parana

XXVII. Andean Region

:128 Northern Andes:129 Central Andes

South African Kingdom

XXVIII. Cape Region

:130 Cape Province

Australian Kingdom

XXIX. Northeast Australian Region

:131 North Australia:132 Queensland:133 Southeast Australia:134 Tasmania

XXX. Southwest Australian Region

:135 Southwest Australia

XXXI. Central Australian or Eremaean Region

:136 Eremaea

=Antarctic Kingdom=

XXXII. Fernandezian Region

:137 Juan Fernández

XXXIII. Chile-Patagonian Region

:138 Northern Chile:139 Central Chile:140 Pampas:141 Patagonia:142 Tierra del Fuego

XXXIV. Region of the South Subantarctic Islands

:143 Tristan-Gough:144 Kerguelen

XXXV. Neozeylandic Region

:145 Lord Howe:146 Norfolk:147 Kermadec:148 Northern New Zealand:149 Central New Zealand:150 Southern New Zealand:151 Chatham:152 New Zealand Subantarctic Islands

References

* Good, Ronald, 1947. "The Geography of Flowering Plants". Longmans, Green and Co, New York

* Takhtajan, Armen, 1986. "Floristic Regions of the World". (translated by T.J. Crovello & A. Cronquist). University of California Press, Berkeley.