Leaf trait Adaptation in Grewia optiva Drummond along Altitudinal Gradient in the North Western Himalayas

The current study was carried out between year 2020-2023 in the Department of Tree Improvement and Genetic Resources, College of Forestry, Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.). This study was carried out in four altitudinal ranges of Himachal Pradesh and Uttarakhand (400 to 800 m (A1), 801-1200 m (A2), 1201-1600 m (A3), and 1601-2000 m (A4) above mean sea level (a m s l). Leaf morphometric traits such as leaf area, leaf length, leaf width and petiole length increased from the A1 (400-800 m) altitudinal zone to the A2 (800-1200 m). These apparent characteristics, however, declined more as the altitudinal range increased from A2 to A4. Maximum values were reported for A2 (800-1200 m altitudinal range) in relation to average leaf area, length, width, and petiole length. The reason being the as elevation increased, leaves became thicker and water content reduced and leaves size became smaller. Plants can develop adaptive strategies in response to environmental change produced by an elevational gradient as elevation increases, the temperature always drops, limiting leaf area expansion due to heat and energy availability. However, according to our findings, the leaf area steadily increase up to 800-1200 m a m s l (A2 altitudinal zone). This counterintuitive pattern could be explained by the impact of precipitation and temperature fluctuations on LA.