Distribution patterns of alpine flora for long-term monitoring of global change along a wide elevational gradient in the Western Himalayas

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In the current context of climate change, the Western Himalayas are thought to be warming faster than the global average rate. Despite this rapid warming, our understanding of alpine vegetation composition and the underlying factors shaping its patterns in the Western Himalayan alpine highlands of Pakistan remains limited. Extensive field sampling was conducted at 24 sites ranging in altitude from 3300 m to 4200 m. The entire altitudinal range was divided into three belts i.e., low-altitude sites, medium-altitude sites, and high-altitude sites (HAS). Results revealed that alpine flora consisted of 251 species (belonging to 51 families. The findings revealed that 83 of the 251 species evaluated contributed significantly to the change in species composition between three altitudinal sites. The species that contributed the most to the variance in species composition between communities made up 75 % of the total, demonstrating that these species are important in structuring plant communities at different altitudes. Among the alpine flora, a significant (49 %) dominance was observed from nine families, comprising a total of 123 species. The largest family, Asteraceae, had the highest number of species, followed by Poaceae and Rosaceae. Hemicryptophytes emerged as the prevailing life form, while Microphylls were the dominant leaf type. Phytosociological Indices revealed that diversity levels decreased with increasing altitude, indicating a significant impact of altitude on plant diversity. Canonical correspondence analysis suggested that altitude, grazing, and soil erosion are important in explaining variance in plant distribution patterns in the alpine flora. Twelve indicator species were discovered in three different altitudinal groups. In the LAS, Bistorta affinis, Geranium himalayense, Poa nemoralis, and Sibbaldia cuneata, had a significant indicator value, whereas in the medium-altitude sites MAS Allium humile, Bistorta affinis, Juniperus communis, and Rhododendron campanulatum had significant p-values. In high altitude sites HAS, indicator plants were Bistorta affinis, Juniperus communis. Our results identified 51 vulnerable species with very low abundance values whereas 17 threatened species having extremely low (<0.1) abundance values are a vital conservation priority in the region. Results may be helpful to formulate immediate conservation management strategies to conserve the precious floristic wealth of the alpine Region.