Title : Interpreting of Circum Euxinian (Russian Black Sea to Turkey) disjunctive distribution of sub Mediterranean pseudomaquis plant community
Abstract:
An understanding of the formation of scattered patches of the Mediterranean pseudomaquis along the coastal region of the Black Sea, requires consideration of the recent geological history of the two seas. The most important crises in the recent history of the Mediterranean Sea occurred during the ‘Messinian Salinity Crisis’, occurred in Early Pleistocene (5.96 to 5.33 mya) (Gautier et al., 1994). This event influenced the net of hydrological balance, climate, and biotas of the Mediterranean Sea’s and Black Sea’s adjacent terrestrial ecosystems. The constantly humid climate conditions suitable in past geological time, according mentioned ,,crisis” converted into another, Mediterranean-type climate with hot, dry summer months and a cool, wet winter (Gratsianskii, 1971). The moist subtropical laurel forests (laurisila) largely retreated and the present thermo-Mediterranean vegetation evolved, dominated by coniferous and flowering screlophilous trees and shrubs (Wulf, 1944). During Early Pliocene the Mediterranean Region’s climate and phytocenosis (first of all Mediterranean maquis) largely influenced to the adjacent regions with non-Mediterranean climate including the Black Sea Basin’s regions (Wulf, 1944). Transformation of typical (primary) maquis into pseudomaquis in the circum-Euxinain region determined formation of patches (relict niches) of the Mediterranean enclaves in a narrow strip along the Black Sea coast. This area is characterized by significant combination of Mediterranean and Euxinian (e.g., deciduous oak species) elements. Four disjunct populations of pseudomaquis relict patches in overstory and midstory still exists along the Black Sea region: (1) the northwestern part of Russian Black Sea coast (Juniperus spp., Pistacia atlantica (P. mutica), (2) easternward, isolate populations of pseudomaquis of Abkhazeti West Georgia (Pinus brutia var. pityusa), Arbutus andrachne and Erica arborea, (3) northern patch in southwestern Georgia, Adjara (A. andrachne), (4) Turkish Black Sea region (Pinus pinea, Arbutus andrachne, and Erica arborea). All these relict patches are vivid example of natural heritage of the Western Caucasus.
