Differences between Deciduous and Evergreen Broad-leaved Trees in the Pattern of Seasonal Change of Leaf-scale Photosynthetic Net Assimilation Rate and Transpiration Rate.

Abstract

Field observations were carried out to compare the diurnal and seasonal pattern of net assimilation rate and transpiration rate of leaves of several evergreen broad-leaved trees and deciduous broad-leaved trees. The patterns of the seasonal changes of net assimilation rate, transpiration rate and stomatal conductance were different between deciduous trees and evergreen trees. The net assimilation rate and stomatal conductance of the deciduous trees peaked in early spring and declined rapidly after summer. The evergreen trees had a relatively low net assimilation rate and stomatal conductance with quite suitable environmental conditions in spring, and the decline after summer was less than that of deciduous trees. These differences in pattern correspond to the differences in the pattern of the seasonal change of leaf greenness which is considered to have close relationship between leaf chlorophyll content.