Transpiration of Trees in a Tropical Rainforest

The tritium method was used to measure the transpiration of twenty trees in a tropical rainforest in the Amazon Territory of Venezuela. Transpiration rates ranged from 2-7 1 day-' for small understorey trees to 1180 1 day-' for large canopy trees. Transpiration rates were highly correlated (r = 0 96) with the sapwood area of trees. Transpiration rate, as a function of sapwood area, was independent of species and independent of soil type on which trees were growing.