Vegetation Diversity of Screes and Taluses of The Pamir and South-Western Tian Shan in Middle Asia

Abstract

This paper presents the results of phytosociological research on scree vegetation of the Pamir and south-western Tian Shan. We collected 222 phytosociological relevés during field studies conducted in 2015–2019, applying the Braun-Blanquet approach. We identified 21 plant communities on mobile and stabilized screes of colluvial cones, aprons and fans, inhabiting mainly the montane and alpine belts in several ranges (e.g. Peter the First, Alichur, Shugnan, Shachdarian, Darvaz, Rushan, Vanch, Fergana, Kyrgyz and Terskey ranges). As a result we provide the first comprehensive hierarchical syntaxonomic synopsis of scree communities at montane and alpine elevations in the eastern Middle Asia. The collected vegetation relevés represent the majority of the variation among the phytocoenoses of gravel, pebble, cobble and rock block slides and screes in the montane and alpine belts. As a result of field studies and Twinspan analyses, nine associations were identified on screes of the Pamir and western Tian Shan. All these communities were assigned to the Sileno brahuicae-Lactucetalia orientalis Nowak et al. 2021. Additionally, within the nitrophilous compact gravel screes one subassociation of Corydalidetum kashgaricae trigonelletosum gontscharovii was distinguished. In the most arid zone two additional plant associations and one subassociation were identified in gravelly semi-deserts zone. The main factors determining the species composition of the studied associations are scree mobility, rock particle size, elevation above sea level and slope inclination. Our research revealed considerable diversity of scree habitats of montane and alpine belts what might be astonishing regarding harsh environment of this mountainous territory. However, a great number of lineages that evolved here and particularly rich species pool of this habitat in Middle Asia facilitate remarkable diversity among vegetation of taluses and screes. The distinctiveness of species composition is additionally enhanced by high degree of endemism of chasmophytic habitats in the eastern part of Middle Asia. Despite recent developments, the prominent chasmophytic vegetation of Middle Asia still needs thorough studies focused on its relationship to semi-desert, tall-forb and petrophytic communities of high mountains of the Pamir, Hindu-Kush, Kunlun and Central Tian Shan.

Four Remarkable Additions to the Biodiversity of Chinese Mosses

“…The vegetation of Altai and Tianshan has apparent vertical distribution belts caused by climate and topography, including desert, steppe zone, mixed conifer, coniferous forest, sub-alpine meadow belt, alpine meadow and alpine vegetation zones. Compared with those of Altai and Tianshan, the Kunlun Mountains lack forest zones, and the distribution belts of the desert and steppe of mountains are rather broad [ 23 , 24 ].…”

Phytosociological survey of juniper wood vegetation in Tajikistan (Middle Asia)

“…This is also reflected in the precipitation pattern with winter (spring) rainfall in Southwest Asia and summer peak rainfall in Central Asia. Such a strong climatic, floristic and environmental gradient is also apparent in many other vegetation types, especially steppes, semi-deserts and scree vegetation (see Nowak et al, 2016Nowak et al, , 2018Nowak et al, , 2021 and should perhaps become a reason for the revision of the phytogeographic division of Middle & Central Asia. For this reason, we believe that the division of Tajikistan's juniper forests should take into account this fundamental difference in climatic conditions and may be reflected even at the level of the phytosociological class.…”