Transpiration of urban tree species in Chulalongkorn University Centenary Park

Abstract

Urbanization has caused significant environmental problems such as atmospheric pollution and especially climate change. These problems can be solved by building urban greenery and promotes sustained management for mitigates excess urban heating by ecosystem service as transpiration of urban trees and its response to environmental factors in different seasons. We estimated the transpiration rate of four urban tree species in Chulalongkorn University Centenary Park and analyzed its seasonal difference. The studied species were Lagerstroemia floribunda (Crepe Myrtle), Afzelia xylocarpa (Black rosewood), Homalium tomentosum (Moulmein lancewood), and Bauhinia purpurea (Orchid Tree) that had diffuse-porous xylem. Our results found that daily transpiration individual species pattern of both wet and dry seasons had a similar pattern. In dry season had transpiration rate higher than wet season. Moreover, the relationships between daily transpiration rate (E) and vapor pressure deficit (VPD) differ among species. Transpiration increased with VPD when VPD increased in most species with an exponential pattern except A. xylocarpa where increased with an exponential saturating pattern. These results can be used to manage irrigation in urban greening effectively and apply in the management of urban greening to be sustainable by selecting suitable urban tree species that maintain transpiration in both seasons and be less affected by changing from the urban environment.