Physiological Responses of Dominant Alpine Plant Species to Environmental Gradients on the Tibetan Plateau

Understanding how plant physiological traits respond to environmental variation is essential for explaining plant performance in alpine ecosystems. Based on field sampling along an elevational transect on the Tibetan Plateau, we quantified osmotic adjustment compounds, antioxidant indicators, and plant hormones in leaves of different species to examine interspecific differences in sensitivity to temperature and precipitation to characterize patterns of physiological plasticity among alpine plants. Along the elevational gradient, declining temperature results in increasing cold stress, whereas lower elevations are associated with reduced precipitation and intensified drought stress. Temperature primarily influenced plant physiological trait expression by promoting growth-related physiological processes, while precipitation variability mainly regulated traits associated with water stress. The three dominant alpine meadow species exhibited distinct patterns of physiological plasticity: Poa litwinowiana showed coordinated regulation of growth and defense pathways, whereas Carex moorcroftii and Carex parvula displayed more conservative response strategies, with physiological regulation tending to maintain homeostasis rather than strongly activating stress responses. These interspecific differences in physiological regulation were significantly associated with variations in plant height, cover, and dominance, providing trait-level physiological insights relevant to plant performance.