Trait-based insights into hypercold resilient Haller's sedge (Carex halleriana Asso) along elevation gradient

Understanding trait-based responses of alpine plants to elevation-induced environmental stressors is crucial for mitigating the impacts of rapid climate change. This study investigated the morpho-anatomical and physiological adaptations of Carex halleriana Asso (Haller's sedge) along an elevational gradient (1807-2841 m) in the western Himalayas of Pakistan. Populations were examined for morphological traits, anatomical characteristics of roots, stems, leaves, and leaf sheaths, as well as key physiological parameters including ionic composition, chlorophyll pigments, osmolyte accumulation, and antioxidant activity. High-elevation populations (e.g., Thandiani) exhibited conservative growth strategies, characterized by reduced root length, multilayered epidermis, increased lignification, and elevated levels of stress-related metabolites such as glycine betaine, ascorbic acid, and H₂O₂, reflecting enhanced cold-stress resilience. In contrast, mid- and low-elevation populations displayed traits associated with greater growth potential and resource acquisition, including expanded vascular bundles, higher ion uptake, and increased photosynthetic pigment concentrations. Multivariate analyses revealed strong associations between soil and environmental variables and the structural-functional traits of C. halleriana, highlighting the pivotal role of elevation, moisture availability, and soil ion composition in shaping local adaptation. Overall, these findings emphasize the pronounced phenotypic plasticity and ecological resilience of C. halleriana, offering valuable insights for biodiversity conservation and ecosystem restoration in alpine regions under changing climatic conditions.