the aggregate of plant communities that belong to the zonal vegetation of a particular zone but are found outside that zone because of certain conditions. Extra-zonal vegetation usually constitutes small areas of the plant cover, areas with conditions atypical for the zone. For example, oak forests in the steppe zone are confined to gorges, and the Kungur Forest Steppe is confined to outcroppings of calcareous rock in the southern taiga subzone. In contrast to intrazonal vegetation, which also occupies small areas and never occupies zonal positions, extrazonal vegetation is confined to the level-divide areas (placors) in other zones. The term “extrazonal vegetation” was introduced in 1915 by tne Polish biologist J. Paczoski.
A. G. VORONOV