Urban green coverage is expected to play a role in mitigating heat-island phenomenon and in providing habitats for wildlife in city region where vegetation is extremely limited. To be fully functional in these services, the green covers should be well-conditioned. However, plants in urban environment are subjected to multiple stresses. Specifically, roadside trees, grown in a small underground unit receiving full sunlight, could be under severe water stress.

We previously reported that the stomatal conductance and transpiration were decreased in the roadside trees in mid-summer because of the low soil water content and the high temperature of their habitat (Osone et al . 2011). However, the degree of decrease differed largely between species.

In the present study, we focused on how these differences in water stress between species could occur. The leaf physiological (photosynthetic capacity, water potential, Fv/Fm and nitrogen content) and anatomical properties were measured in three typical roadside tree species, Prunus x yedoensis, Zelkova serrata and Ginkgo biloba at the beginning of August. With these results, we discuss adequate species selection for roadside trees and their management.