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 some schemes, areas of phytochoria are classified hierarchically, e.g., in Floral (or Floristic, Phytogeographic) Kingdoms, Regions and Provinces, sometimes including the categories Empire and Domain, while others prefer not to rank areas, referring to them simply as "regions" or "phytochoria".[1]

The 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 relationships.[2] Phytochoria are defined by their plant taxonomic composition, while other schemes of regionalization (e.g., phytophysiognomies, formations, biomes) may variably take in account, according to the author, the apparent characteristics of a community (the dominant life-form), environment characteristics, the fauna associated, anthropic factors or political-conservationist issues.[3]

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. Phytochoria 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, and 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.[4]

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.

Good's floristic regionalization

Floristic kingdoms

Botanist Ronald Good identified six floristic kingdoms (Boreal or Holarctic, 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.

Takhtajan's floristic regionalization

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.

Holarctic Kingdom

Flora regions in Europe

I. Circumboreal Region

1 Arctic
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 Californian
63 Sonoran
64 Mexican Highlands

Paleotropical Kingdom

X. Guineo-Congolian Region

65 Upper Guinean forests
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 The Guianas

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

  1. ↑ Linder, Lovett, Mutke, et al. (2005): A numerical re-evaluation of the sub-Saharan phytochoria. Biologiske Skrifter 55: 229-252.
  2. ↑ JOLY, C.A., AIDAR, M.P.M., KLINK, C.A., McGRATH, D.G., MOREIRA, A.G., MOUTINHO, P., NEPSTAD, D.C., OLIVEIRA, A.A.; POTT, A.; RODAL, M.J.N. & SAMPAIO, E.V.S.B. 1999. Evolution of the Brazilian phytogeography classification systems: implications for biodiversity conservation. Ci. e Cult. 51: 331-348.
  3. ↑ Magno Coutinho, L. (2006) O conceito de bioma. Acta bot. bras. 20(1): 13-23.
  4. ↑ glossary from 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 (February 1998). Vegetation of South Africa, Lesotho and Swaziland: A companion to the Vegetation Map of South Africa, Lesotho and Swaziland. Department of Environmental Affairs and Tourism, Pretoria.
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