STOMATAL AND BOUNDARY-LAYER CONDUCTANCES IN AN AMAZONIAN TERRA-FIRME RAIN-FOREST

Maximum values of stomatal conductance gs were observed near the top of the 40 m deep canopy and they declined towards the forest floor. Observed values of ga also decreased through the canopy, but a slight maximum occurred 20 m from the ground. In the upper part of the three canopy the diurnal maximum in gs occurred in the mid-morning and the value declined for the remainder of the day. This peak was less marked lower in the canopy, and was not present near the forest floor. gs was correlated negatively with specific humidity deficit (D) and positively with solar radiation (S). The response of gs to D increased with increasing S at all but the highest value of S. The lowest value of gs occurred at the same time as the lowest soil water potentials. -from Authors