Uptake of O3 by various street trees.

Abstract

Potted eleven street tree species (Aucuba japonica, Cinnamomum camphora, Daphniphyllum macropodum, Ginkgo biloba, Hedera rhombea, Ligustrum japonicum, Pasania edulis, Prunus yedoensis, Quercus acutissima, Rhododendron oomurasaki, Zelkova serrata) were treated with various concentrations of O3 to investigate the heritable differences in the capacity of O3 uptake. The rates of net photosynthesis and transpiration, and stomatal density were determined for every tree species. Some species showed a linear relationship between O3 concentration and the uptake rate of O3, while other species did not. The analysis using a gas phase diffusive conductance indicated that the nonlineality was assumed to be resulted from the stomatal closure. Concerning those nine tree species which showed the linear increase in O3 uptake rate with O3 concentration, the rate of O3 uptake was ranked as follows: P. yedoensis=H. rhombea>Z. serrata=Q. acutissima>C. camphora=D. macropodum=G. biloba>A. japonica=R. oomurasaki. Those tree species with higher uptake rates of O3 were not characterized with higher stomatal frequency but with higher gas phase conductance for water vapor. This result suggested that the heritable differences in the rates of O3 uptake are determined by the interspecific differences in stomatal conductances.