Abstract
The ratio of the intercellular to ambient CO2 concentrations (Ci/Ca), which is an index of the leaf-level control of the CO2 and H2O exchange between trees and the air, is one of the important parameters for quantifying CO2 and H2O flux over vegetation. In this study, Ci/Ca were calculated from in situ measurements of leaf-level gas exchange rates in a temperate broad-leaved forest in Akou, Hyogo Prefecture, Japan, to examine the seasonal variation of Ci/Ca and the factors controlling Ci/Ca of the temperate broad-leaved trees. In results, the Ci/Ca of the evergreen trees (Quercus glauca, Cinnamomum camphora and Castanopsis cuspidata, ) decreased with growing, and the mature leaves had small variations in Ci/Ca. The Ci/Ca of the deciduous tree (Quercus serrata) decreased with growing, and increased with senescence of leaves. The mean and standard deviation of Ci/Ca of the mature leaves of all trees investigated were 0.640 and 0.063. This result suggests that the mature leaves of the temperate broad-leaved trees had small seasonal and inter-species variations.
