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Alpine ecosystems are characterized by extreme environmental conditions, including cold temperatures, low rainfall, poor soils, and high winds, which severely constrain plant growth and establishment. Despite these challenges, keystone plant species native to these habitats play a vital role in ecosystem restoration and conservation. One such species is Festuca karatavica (Bunge), a tussock grass native to alpine regions of northern Iran and Central Asia, found at elevations ranging from 1800 to 3100 m.a.s. l. This species is particularly valuable as a source of livestock fodder and for its contributions to soil and water conservation. In this study, we investigated the phenology, nutrient content, and ecological preferences of F. karatavica along an altitudinal gradient in its natural habitat on Shirbad Summit, northeast Iran. We also analyzed associated plant species diversity and richness, as well as soil physical and chemical properties. The phenological cycle of F. karatavica begins in early April and concludes with seed shedding by September, with seasonal variations influenced by annual rainfall. Crude protein content, acid detergent fiber (ADF), and neutral detergent fiber (NDF) were highest during early growth stages but declined over the growing season. Its seeds germinate easily without dormancy, suggesting strong regenerative potential. Soil conditions vary across the altitudinal gradient, with sandy loam textures and the highest pH (7.4) and electrical conductivity (EC) observed at the summit, decreasing at lower elevations. Species diversity peaked at mid-elevation (2831 m.a.s.l.), while species richness and evenness were highest at higher (3050 m.a.s.l.) and lower (2720 m.a.s.l.) elevations, respectively. The most favorable habitat for F. karatavica was identified at mid-elevation, where optimal soil nutrients (N, P, and organic C) and mycorrhizal associations supported its growth. Growth at higher altitudes is constrained by poor soil conditions and harsh climatic factors, whereas competition, intensive grazing, and erosion limit its success at lower altitudes.