page_title: Phytochorion
section_title: Holarctic Kingdom
hierarchical_section_title: Phytochorion / Takhtajan (1978, 1986) regionalization / Holarctic Kingdom
caption_attribution_description: English: Floristic regions in Europe and western Siberia, according to Wolfgang Frey and Rainer Lösch 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. References: Frey W, Lösch R (2004) Lehrbuch der Geobotanik. Elsevier, Spektrum; München, Heidelberg; ISBN 3-8274-1193-9 (graphic modified from Walter H (1954) Grundlagen der Pflanzenverbreitung. Einführung in die Pflanzengeographie, II. Teil: Arealkunde. Ulmer, Stuttgart-Ludwigsburg) Frey W, Lösch R (2010) Geobotanik: Pflanzen und Vegetation in Raum und Zeit. 3 ed, Spektrum, Heidelberg, ISBN 978-3-8274-2335-1 Français&#160;: Régions floristiques européennes actuelles (Europe et Siberie occidentale), selon Wolfgang Frey et Rainer Lösch
context_page_description: 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 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" 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 relationships.
caption: Flora regions in Europe
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