Adaptive Mechanism in Quercus brantii Lindl. Leaves under Climatic Differentiation: Morphological and Anatomical Traits

Abstract Leaf traits, which vary across different climatic conditions, can reveal evolutionary changes within a species to adapt to the environment. To examine adaptive mechanisms applied by plants in different climates, we analyzed leaf morphology and anatomical structures in Quercus brantii in the Zagros forests. The trees adapted to the environmental differences with increased dry matter content in a Mediterranean climate, and increasing leaf length, specific leaf area, stomata length (SL), stomata width, stomatal density (SD), stomatal pore index (SPI), trichome length, and width in a sub-humid climate; trichome density was increased in a semi-arid climate. There were strong, positive correlations between SPI with SL and SD. Such traits plasticity probably leads to lower transpiration rates, control of internal temperature and water status, and improved photosynthetic capability under stressing conditions. These findings provide new insights into the adaptive strategies of trees to environmental changes at the morphological and anatomical levels.