Structural and nutrient traits of foliage are important for understanding plant ecological strategies. Understanding structural variations of trees in different environmental conditions helps to reveal adaptation mechanisms. We investigated morphological, chemical and stoichiometric traits in the foliage of four dominant woody species in sub-humid vs. semi-arid of the Zagros forests, west of Iran. Dry matter content, specific leaf area (SLA), stomatal length (SL), stomatal width (SW), density (SD) and stomatal pore index (SPI) traits were higher in the trees growing ina sub-humid climate. In Pistacia atlantica (PA) growing in the semi-arid climate, leaf length, SLA, SD and SPI traits were higher than the sub-humid climate. Leaf phosphorus content of Crataegusaronia (CA) was higher in the sub-humid, whereas PA was higher in the semi-arid climate. In PA and CA, the highest leaf C: P and N: P were in the sub-humid and the semi-arid climate. The relationship between SLA and leaf carbon content was significantly negative in PA. Among the different species, carbon content, nitrogen and phosphorus and their stoichiometry had strong positive and negative relationships in two climates. These results show the response of leaf functional traits to climate changes and how trees function under these changes. Furthermore, the leaf traits showing greater variability due to changes in the environment can be determined.This improved understanding will assist in determining the most important adaptive parameters of trees to climate changes, to provide inputs to global environmental models.
