Vascular plants at extreme elevations in eastern Ladakh, northwest Himalayas

Background: Due to the dry continental climate, the mountains of eastern Ladakh are unglaciated up to 6200-6400m, with relatively large areas of developed soils between 5600 and 6000m covered by sparse subnival vegetation. However, there are no studies on the composition of plant assemblages from such extreme elevations, their microclimates, vertical distributions and adaptive strategies.Aims: The subnival vegetation was described and the relationship between microclimate, species distribution and species functional traits was analysed.Methods: In total, 481 vegetation samples from 91 permanent plots, a floristic database of Ladakh and extensive microclimate measurements were used. Measurements of 15 functional traits were made and their relationship with species distribution between 4600 and 6150m was tested.Results: The subnival zone was characterised by extreme diurnal temperature fluctuations, a short growing season (between 88 and 153days) and low soil temperature during the growing season (between 2.9 degrees C and 5.9 degrees C). It hosted 67 species, mainly hemicryptophytes, and ranged from ca. 5600m to the highest known occurrence of vascular plants in the region (6150m). The most common plant families were Brassicaceae, Asteraceae, Poaceae, Fabaceae and Cyperaceae. Subnival specialists with narrow elevational ranges represented 42% of the flora; these species were shorter, had relatively higher water content and water-use efficiency and contained more nutrients and soluble carbohydrates than species with a wider elevational range.Conclusions: The subnival vegetation of eastern Ladakh is dominated by generalist species with wide vertical ranges and not by high-elevation specialists. These findings, in view of the vast unglaciated areas available for range extension, suggest a relatively high resilience of the subnival flora to climate change in this region.