On the basis of 285 phytosociological images, we have made the first classification of semi-desert vegetation and the so-called dry steppe of the highest elevations of Pamir and central Tienshan in Tajikistan and Kyrgyzstan. We defined eight new assemblages and four communities without syntaxonomic rank. The main factors responsible for the species composition of the studied vegetation are latitudinal and meridional position, average annual temperature and seasonality of precipitation. Despite the fact that this type of vegetation is species-poor, it shows a high degree of distinctiveness and diversity between different mountain ranges, as evidenced by the marked difference in composition between desert steppe and steppe in the Hindu Kush and Pamir.

Abstract

The paper presents the first syntaxonomic overview for the semi-deserts and desert steppes of the alpine belt in the Pamir and south-western Tian Shan Mts. in Tajikistan and Kyrgyzstan with some remarks on its environmental conditions. A total of 285 relevés were sampled in 2015-2019 using the Braun-Blanquet scale. All these samples were classified by the modified TWINSPAN method. Diagnostic species were identified using the phi coefficient as a fidelity measure. The detrended correspondence analysis was used to explore the relationships between groups in the data set and to determine the environmental gradients that predict the species composition and distributional patterns of particular communities. We detected eight associations and four communities. Most of the distinguished vegetation units are assigned to desert steppes and cryophilous semi-deserts of the cold highlands in Central Asia. The main factors responsible for the species composition of the researched vegetation are latitudinal and longitudinal position, mean annual temperature and precipitation seasonality. Despite the fact that this vegetation type is poor in species, it demonstrates a high degree of distinctiveness and diversity between individual mountain ranges, which is evidenced by a clear compositional dissimilarity between desert steppes and steppes in Hindu Kush and in the Pamirs.

Nowak A., Cricket S., Nowak S., Nobis M. 2023. High altitude semi-deserts and desert steppes in the eastern Pamir-Alai and western Tian Shan Mountains (Tajikistan, Kyrgyzstan). Phytocoenologia 51(4), 331-356.

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2023-11-14 11:24:17