Fen and spring vegetation in western Pamir-Alai Mountains in Tajikistan (Middle Asia)

The paper presents the results of phytosociological research on spring and fen vegetation of the western Pamir-Alai Mountains in Tajikistan. In total, 211 releves were sampled during field studies conducted in 2008-2013 and 2015 with application of the Braun-Blanquet method. Plant communities of spring heads and peat-accumulated fens inhabiting the high montane and alpine zones in the Zerayshan, Hissar, Hazratishoh, Darvaz, Turkestan and Peter the 1st Mountains are described. A hierarchical syntaxonomic synopsis of spring and fen plant communities in the western Pamir-Alai Mountains is provided. As a result of field investigations and numerical analyses, three fen associations: Caricetum pseudofoetidae, Allietum fedtschenkoani, and Eleocharido quinqueflorae-Primuletum iljinskii have been distinguished. They were included in the Dactylorhizo umbrosae-Caricion orbicularis alliance, which was proposed to comprise the neutral and alkaline alpine fens of Middle Asia. Additionally, within the Montio-Cardaminetea class three spring associations have been defined: Epilobio tianschanici-Bryetum schleicheri, Clementsieturn semenovii and Codonopsideto dematidi-Cortusetum turkestanicae. Because of their floristic composition vague, and some vaguen comparison to European and other Asiatic spring vegetation, the crenic communities of western Pamir-Alai have been assigned provisionally to a Cratoneurion commutati alliance. A synopsis of the spring and fen plant communities of the western Pamir-Alai is also proposed. The main environmental factors determining the species composition of the sampled vegetation are the amount of dissolved electrolytes, altitude and soil reaction.