Les pelouses subalpines (Alchemilletum plicatissimae ass. nov.) de l'Alborz central (Iran): ultime avancée sud-orientale de l'aire des Festuco-Brometea Br.-Bl. et Tx. 1943
Klein, J. C.; Lacoste, A.
In the Euro-Siberian part of the northern slopes of central Alborz, the subalpine meadows of Alchemilletum plicatissimae grow at a height between 2400 and 3200 m a.s.l. This association is divided into 3 subunits (sub associations) according to altitude. The lowest one, differentiated by Cousinia pinarocephala (2300-2450 m), is related to the meadows which replace the destroyed beech groves; the middle one, juniperetosum communis (2700-2900 m), grows on sites of oak groves; the highest one, juniperetosum sabinae (2900-3200 m), above the upper timberlimit, develops in contact with the Irano-Turanian communities. In spite of a lot of species belonging to the hyrcano-euxinian element, the Alchemilleteum plicatissimae belongs to the Euro-Siberian Festuco-Brometea. Although it contains many species of Festucetalia valesiacae, it nevertheless belongs to a new syntaxon with the rank of an order which, with a distribution over the Great and Little Caucasus, would still have to be named. Due to overgrazing, the association contains many species of Artemisietea. The moderate glaciations in these southern ranges are the cause for the subalpine belt being occupied by Festuco-Brometea species, which usually grow at low altitudes, to the detriment of units such as Seslerietea albicantis, typically subalpine. The same situation occurs in these regions with forest communities of Querco-Fagetea which as subalpine belt take the place of Vaccinio-Piceetea. Accordingly, the syntaxons which now replace the subalpine and alpine belts in western European ranges - the existence of which is linked to the glaciations - would never have reached neither the Caucasus nor the northern slopes of the Alborz mountains. Thus, the low and middle altitude communities occupy the subalpine belt as well while at the alpine belt, autochtonous Caucasian units, belonging to a high syntaxonomic rank, develop.