Geographic area with a relatively uniform composition of plant species
Aphytochorion, 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 (orfloristic, 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 factorsorpolitical-conservationist issues.[5]
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 endemictaxa. 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 mammalfamilies, 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.
In 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]
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]
Armen 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]
(with focus on Europe, matching the image on the right)[22][23]
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).
Critiquing 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]
^ abDrude, 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].
^Werger, M. J. A. & H. van Gils. 1976. Phytosociological classification problems in chorological border line areas. J. Biogeogr. 3: 49–54, [5].
^glossaryArchived 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].
^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].
^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 (2010). Geobotanik: Pflanzen und Vegetation in Raum und Zeit (3 ed.). Heidelberg: Spektrum. ISBN978-3-8274-2335-1.
^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
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].
