Functional traits variation in Arundo donax across climatic and altitudinal gradients in Azad Jammu and Kashmir

Variation in abiotic conditions along elevation gradients can strongly influence plant phenology and functional traits. Despite their importance, studies linking leaf functional traits and environmental conditions across elevations remain limited. Arundo donax (Poaceae) is a widely distributed riparian grass of ecological and economic significance. Leaf samples were collected from six elevations (600–2350 m) in Azad Jammu and Kashmir to assess trait variation under diverse climatic and topographic conditions. Samples were sectioned using a rotary microtome and examined under a stereo microscope for anatomical analysis. Regression analyses indicated that leaf area was positively associated with mean annual precipitation (MAP), mean annual temperature (MAT), and longitude, but negatively associated with latitude and slope. Leaf dry matter content decreased with most variables except slope. Stomatal traits and tissue ratios showed coordinated patterns along climatic and topographic gradients. Strong trait associations were evident, with significant coupling among anatomical and stomatal traits. Lognormal distribution patterns suggested distinct responses of morphological and stomatal traits at 1280 m, 1720 m, and 2350 m. Overall, the findings indicate that climatic and topographic variation is closely linked to coordinated changes in A. donax leaf traits, highlighting the role of functional variation in mediating plant adaptation to environmental heterogeneity.