A multiplicative stomatal conductance model was constructed to estimate stomatal O-3 uptake of Fagus crenata exposed to O-3 under different N loads to the soil. Our stomatal conductance model included environmental functions such as the stomatal responses of E crenata to diurnal changes, chronic O-3 stress (AOT0), acute O-3 stress (O-3 concentration), and nitrogen load to soil. The model could explain 62% of the variability in stomatal conductance. We suggest therefore that stomatal closure induced by O-3 and N load-induced soil acidification must be taken into account in developing a stomatal conductance model for estimating stomatal O-3 uptake for future risk assessment of O-3 impact on Japanese forest tree species such as E crenata. (C) 2013 Elsevier Ltd. All rights reserved.