Leaf carbon isotope ratio and water use efficiency of urban roadside trees in summer in Kyoto city

Abstract

AbstractThe effect of summer climate on leaf carbon isotope composition (δ13C) of the major roadside tree species Prunus × yedoensis (P. yedoensis) was investigated in Kyoto city, Japan, to explore the implications for alterations in urban environments. Temperature and the vapor pressure deficit were higher at sites of higher traffic volumes, possibly affected by a heat island effect. The leaf δ13C of P. yedoensis trees was affected strongly by leaf carbon isotope discrimination (Δ), with much less effect of δ13C on atmospheric CO2. Leaf Δ values in the summer were smaller at sites of higher traffic volumes with high atmospheric temperatures, suggesting a higher long‐term water use efficiency (WUE) at these sites. Gas exchange measurements of P. yedoensis leaves indeed suggested a higher intrinsic WUE at sites of higher traffic volumes with high atmospheric temperatures. These results suggest that leaf Δ is related to the response of WUE to summer climates, and that leaf δ13C in urban areas is a useful tracer for understanding the influences of urban environments on plant photosynthetic processes.