string: Similar results were also reported by Bassuk et al. (2003) and Swoczyna et al. (2010). They showed that P. calleryana was one of the most stress tolerant species in road side conditions among the different tree species of the USA and Poland respectively. Peters et al. (2010) found that ring porous species exercise more stomatal regulation across the growing season to protect the xylem against cavitation, so diffuse porous genera showed higher rates of water loss during June and July.