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,[1] or also in kingdoms, regions and provinces,[2] 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".[3]
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.[4] 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.[5]
Explanation
editSeveral 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 taxa. 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" (Werger & van Gils, 1976)[6] 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,[7] mainly in Africa.[8]
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.
Early schemes
editIn the late 19th century, Adolf Engler (1844-1930) was the first to make a world map with the limits of distribution of floras, with four major floral regions (realms).[9][10] His Syllabus der Pflanzenfamilien, from the third edition (1903) onwards, also included a sketch of the division of the earth into floral regions.[11]
Other important early works on floristics includes Augustin de Candolle (1820),[12] Schouw (1823),[13] Alphonse de Candolle (1855),[14] Drude (1890),[1] Diels (1908),[15] and Rikli (1913).[16]
Good (1947) regionalization
edit
Botanist Ronald Good (1947) 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 regions and provinces. The Paleotropical kingdom is divided into three subkingdoms, which are each subdivided into floristic regions. Each of the other five kingdoms are subdivided directly into regions. There are a total of 37 floristic regions. Almost all regions are further subdivided into floristic provinces.[17]
Takhtajan (1978, 1986) regionalization
editArmen Takhtajan (1978, 1986), 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.[18][19][20][21]
- 1 Arctic province
- 2 Atlantic Europe province
- 3 Central Europe province
- 4 Illyria or Balkan province
- 5 Pontus Euxinus province
- 6 Caucasus province
- 7 Eastern Europe province
- 8 Northern Europe province
- 9 Western Siberia province
- 10 Altai-Sayan province
- 11 Central Siberia province
- 12 Transbaikalia province
- 13 Northeastern Siberia province
- 14 Okhotsk-Kamchatka province
- 15 Canada incl. Great Lakes province
- 16 Manchuria province
- 17 Sakhalin-Hokkaidō province
- 18 Japan-Korea province
- 19 Volcano-Bonin province
- 20 Ryūkyū or Tokara-Okinawa province
- 21 Taiwan province
- 22 Northern China province
- 23 Central China province
- 24 Southeastern China province
- 25 Sikang-Yuennan province
- 26 Northern Burma province
- 27 Eastern Himalaya province
- 28 Khasi-Manipur province
- 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 province
- 31 North American Prairies province
- 32 Vancouverian province
- 33 Rocky Mountains province
- 34 Azores province
- 35 Madeira province
- 36 Canaries province
- 37 Cape Verde province
- 38 Southern Morocco province
- 39 Southwestern Mediterranean province
- 40 South Mediterranean province
- 41 Iberia province
- 42 Baleares province
- 43 Liguria-Tyrrhenia province
- 44 Adriatic province
- 45 East Mediterranean province
- 46 Crimea-Novorossijsk province
VIII. Irano-Turanian region
edit8A. Western Asiatic subregion
edit- 49 Mesopotamia province
- 50 Central Anatolia province
- 51 Armenia-Iran province
- 52 Hyrcania province
- 53 Turania or Aralo-Caspia province
- 54 Turkestan province
- 55 Northern Baluchistan province
- 56 Western Himalaya province
8B. Central Asiatic subregion
edit- 57 Central Tien Shan province
- 58 Dzungaria-Tien Shan province
- 59 Mongolia province
- 60 Tibet province
IX. Madrean region
edit- 61 Great Basin province
- 62 Californian province
- 63 Sonoran province
- 64 Mexican Highlands province
- 65 Upper Guinean forests province
- 66 Nigeria-Cameroon province
- 67 Congo province
- 68 Zanzibar-Inhambane province
- 69 Tongoland-Pondoland province
12A. Zambezian subregion
edit- 70 Zambezi province
12B. Sahelo–Sudanian subregion
edit12C. Eritreo–Arabian subregion
edit- 73 Somalia-Ethiopia province
- 74 South Arabia province
- 75 Socotra province
12C. Omano-Sindian subregion
edit- 76 Oman province
- 77 South Iran province
- 78 Sindia province
XIII. Karoo-Namib region
edit- 79 Namibia province
- 80 Namaland province
- 81 Western Cape province
- 82 Karoo province
- 83 St. Helena and Ascension province
- 84 Eastern Madagascar province
- 85 Western Madagascar province
- 86 Southern and Southwestern Madagascar province
- 87 Comoro province
- 88 Mascarenes province
- 89 Seychelles province
XVI. Indian region
edit- 90 Ceylon (Sri Lanka) province
- 91 Malabar province
- 92 Deccan province
- 93 Upper Gangetic Plain province
- 94 Bengal province
XVII. Indochinese region
edit- 95 South Burma province
- 96 Andamans province
- 97 South China province
- 98 Thailand province
- 99 North Indochina province
- 100 Annam province
- 101 South Indochina province
XVIII. Malesian region
edit18A. Malesian subregion
edit- 102 Malaya province
- 103 Borneo province
- 104 Philippines province
- 105 Sumatra province
- 106 Java province
18B. Papuan subregion
edit- 107 Celebes province
- 108 Moluccas and West New Guinea province
- 109 Papua province
- 110 Bismarck Archipelago province
XIX. Fijian region
edit- 111 New Hebrides province
- 112 Fiji province
- 113 Micronesia province
- 114 Polynesia province
XXI. Hawaiian region
edit- 115 Hawaii province
XXII. Neocaledonian region
edit- 116 New Caledonia province
XXIII. Caribbean region
edit- 117 Central America province
- 118 West Indies province
- 119 Galápagos Islands province
- 120 The Guianas province
XXV. Amazon region
editXXVI. Brazilian region
edit- 123 Caatinga province
- 124 Central Brazilian Uplands province
- 125 Chaco province
- 126 Atlantic province
- 127 Paraná province
XXVII. Andean region
edit- 128 Northern Andes province
- 129 Central Andes province
XXVIII. Cape region
edit- 130 Cape province
- 131 North Australia province
- 132 Queensland province
- 133 Southeast Australia province
- 134 Tasmania province
- 135 Southwest Australia province
XXXI. Central Australian or Eremaean region
edit- 136 Eremaea province
XXXII. Fernandezian region
edit- 137 Juan Fernández province
XXXIII. Chile-Patagonian region
edit- 138 Northern Chile province
- 139 Central Chile province
- 140 Pampas province
- 141 Patagonia province
- 142 Tierra del Fuego province
XXXV. Neozeylandic region
edit- 145 Lord Howe province
- 146 Norfolk province
- 147 Kermadec province
- 148 Northern New Zealand province
- 149 Central New Zealand province
- 150 Southern New Zealand province
- 151 Chatham province
- 152 New Zealand Subantarctic Islands province
Regionalization according to Wolfgang Frey and Rainer Lösch (2004, 2010)
edit.png)
- The central European region and the central Russian region are sister regions.
- The border between them is similar to the Fagus sylvatica limit (January, day-time temperature average: above -2 °C).
- The border between the central Russian region and the boreal region is similar to the Quercus spp. limit (Day-time temperature average: above 10 °C, 4 months per year).
- The border between the boreal region and the arctic region is similar to the tree line, taiga/arctic tundra limit (July, day-time temperature average: above 10 °C).
- The border of the Atlantic region is the limit of no frost (average), Gulf Stream influence.
- The warm islands in the Atlantic Ocean are in the Macaronesia region: isolated populations in a more humid environment.
- The Mediterranean region is similar to the occurrence of wild Olea europea and wild Cistus salviifolius (Olea europea is grown very North in Italy).
- The border between the submediterranean region and the central European region is similar to the alpine arc (upper Rhone, upper Rhine, lower Danube), a weather barrier.
- The Pontic region border is similar to the tree line/ steppe limit (less than 450 mm precipitation per year).
- The Turanian region has a semi-arid climate.
Liu et al. (2023, 2024) Regionalization
editCritiquing previous attempts for their lack of phylogenetic relationships in the construction of their regions, Liu et al. incorporated distribution data alongside phylogenetic relationships to configure their realms. This led to the classification of eight realms organized into two super-realms and each composed of a number of sub-realms.[24]
- Gondwanan super-realm
- 1 African
- 2 Indo-Malesian
- 3 Australian
- 4 Novozealandic
- 5 Neotropical
- 6 Chile–Patagonian
- Laurasian super-realm
- 7 Holarctic
- 8 Saharo-Arabian
Differences from Takhtajan's floristic kingdoms mainly focus on emphasizing the uniqueness of certain realms that he had as subdivisions within kingdoms. Two examples are separating some kingdoms into two separate realms, as happened to the Paleotropical and Antarctic kingdoms, reasoning that they have been separated form each other for long enough time to constitute a different phylogenetic trajectory. The merging of the Cape floristic kingdom with the African realm was based by the low endemism of higher taxonomic ranks, which could be found outside the cape region in the rest of Africa. The final major change is the separation of the Saharo-Arabian realm from the Holarctic kingdom, though they admit the northern boundary is not clear, with flora from the Holarctic being found within this area.
After publishing their regions, Dr. Hong Qian criticized Liu et al. for the inclusion of nonnative distributions in their analyses.[25] In response to this, the group cleaned their data to remove nonnative ranges and reassessed their regions. They suggest that the previous inclusion of exotic species did not significantly affect their mapping and found that the cleaned data revealed the same floristic realms.[26]
References
edit- ^ a b Drude, O. (1890). Handbuch der Pflanzengeographie. Stuttgart: Engelhorn, [1], [2]. French translation: Manuel de géographie botanique. Paris: P. Klincksieck, 1897. 552 p., [3].
- ^ Braun-Blanquet, J. (1932). Plant sociology; the study of plant communities. New York and London, McGraw-Hill, [4].
- ^ Linder, Lovett, Mutke, et al. (2005): A numerical re-evaluation of the sub-Saharan phytochoria. Biologiske Skrifter 55: 229-252.
- ^ 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.
- ^ Magno Coutinho, L. (2006) O conceito de bioma. Acta bot. bras. 20(1): 13-23.
- ^ Werger, M. J. A. & H. van Gils. 1976. Phytosociological classification problems in chorological border line areas. J. Biogeogr. 3: 49–54, [5].
- ^ glossary Archived 2008-04-11 at the Wayback Machine from Bredenkamp, George J.; Granger, J. Ed; Hoffman, M. Timm; Lubke, Roy A.; Mckenzie, Bruce; Rebelo, A. (Tony) & Noel, van Rooyen (February 1998). Low, A. Barrie & Rebelo, A. (Tony) G. (eds.). 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.
- ^ Prance, G. T. (1989). American Tropical forests, in Ecosystems of the World, Vol. 14B. Tropical Rain Forest Ecosystems, (eds H. Lieth and M. J. A. Werger), Elsevier, Amsterdam, pp. 99–132, [6].
- ^ Engler, A. (1879-1882). Versuch einer Entwicklungsgeschichte der Pflanzenwelt. 2 vols., Leipzig.
- ^ Cox, C. B., Moore, P.D. & Ladle, R. J. 2016. Biogeography: an ecological and evolutionary approach. 9th edition. John Wiley & Sons: Hoboken, p. 10, [7].
- ^ Engler, Adolf (1903). Syllabus der Pflanzenfamilien: eine Übersicht über das gesamte Pflanzensystem mit Berücksichtigung der Medicinal- und Nutzpflanzen nebst einer Übersicht über die Florenreiche und Florengebiete der Erde zum Gebrauch bei Vorlesungen und Studien über specielle und medicinisch-pharmaceutische Botanik (3rd ed.). Berlin: Gebrüder Borntraeger Verlag. p. 233. Retrieved 31 January 2014.
- ^ de Candolle, Augustin (1820). Essai Élémentaire de Géographie Botanique. In: Dictionnaire des sciences naturelles, Vol. 18. Flevrault, Strasbourg, [8].
- ^ Schouw, J. F. (1822). Grundtræk til en almindelig Plantegeographie. Copenhagen, Gyldendalske Boghandels Forlag. German translation: Grundzüge einer allgemeinen Pflanzengeographie, Berlin, 1823, [9].
- ^ de Candolle, Alphonse (1855). Géographie botanique raisonnée. Paris: V. Masson, [10].
- ^ Diels, L. (1908). Pflanzengeographie. Göschen, Leipzig, [11]; 5th ed. rev. 1958 (F. Mattick), De Gruyter, Berlin.
- ^ Rikli, M. (1913). "Geographie der Pflanzen (Die Florenreiche)". In: Handwörterbuch der Naturwissenschaften 4:776–857, [12].
- ^ Good, R. (1947). The Geography of Flowering Plants. Longmans, Green and Co, New York, [13]. 2nd ed., 1953, [14].
- ^ Takhtajan, A. 1969. Flowering plants: origin and dispersal. Transl. by C. Jeffrey. Oliver &. Boyd, Edinburgh. 310 pp. [15].
- ^ Тахтаджян А. Л. Флористические области Земли / Академия наук СССР. Ботанический институт им. В. Л. Комарова. — Л.: Наука, Ленинградское отделение, 1978. — 247 с. — 4000 экз. DjVu, Google Books.
- ^ Takhtajan, A. (1986). Floristic Regions of the World. (translated by T.J. Crovello & A. Cronquist). University of California Press, Berkeley, PDF, DjVu.
- ^ Cox, C. B. (2001). The biogeographic regions reconsidered. Journal of Biogeography, 28: 511-523, [16].
- ^ Frey, Wolfgang; Lösch, Rainer (2004). Lehrbuch der Geobotanik. München, Heidelberg: Elsevier, Spektrum. ISBN 3-8274-1193-9.
- ^ Frey, Wolfgang; Lösch, Rainer (2010). Geobotanik: Pflanzen und Vegetation in Raum und Zeit (3 ed.). Heidelberg: Spektrum. ISBN 978-3-8274-2335-1.
- ^ Liu, Y., Xu, X., Dimitrov, D., Pellissier, L., Borregaard, M. K., Shrestha, N., Su, X., Luo, A., Zimmermann, N. E., Rahbek, C., & Wang, Z. (2023). An updated floristic map of the world. Nature Communications, 14(1). https://doi.org/10.1038/s41467-023-38375-y
- ^ Qian, H. (2024). Reassessing data quality underlying the recently updated floristic map of the world. Nature Communications, 15(1). https://doi.org/10.1038/s41467-024-47543-7
- ^ Liu, Y., Xu, X., Dimitrov, D., Rahbek, C., & Wang, Z. (2024). Reply to: Reassessing data quality underlying the recently updated floristic map of the world. Nature Communications, 15(1). https://doi.org/10.1038/s41467-024-47544-6
Bibliography
edit- Frodin, D.G. (2001). Guide to Standard Floras of the World. An annotated, geographically arranged systematic bibliography of the principal floras, enumerations, checklists and chorological atlases of different areas. 2nd ed. (1st edn 1984), pp. xxiv, 1100, .Cambridge University Press, Cambridge, [17].