Effects of changing temperature on leaf surface water-film chemistry and trace gas exchange processes over terrestrial vegetation. A contribution to ACCENT CCAQ Topic 2

The effects of an increase of air temperature on the stomatal conductance of beech, a widespread tree specie in Europe, have been examined by using a Jarvisian model of stomatal conductance calibrated on a sixth months long field experiment in northern Italy. An increase of few degrees centigrade in air temperature resulted in very little changes in the mean stomatal conductance of the trees, but the diurnal course of this important parameter underwent an evident change, consisting in increased stomatal conductance values in the first hours of the day and decreased values in the rest of the day, and particularly in the afternoon.