What are the limits on forest evaporation?

Abstract

Recent research suggests that the limits on forest evaporation are only loosely related to net radiant energy. Dry-canopy evaporation appears to be limited substantially by stomatal responses to external environmental factors such as radiation, temperature, vapour pressure deficit and carbon dioxide concentration whereas wet-canopy evaporation appears to be constrained primarily by the frequency and duration of rainfall. The critical review presented herein indicates that the research on dry-canopy evaporation is now in a creative and exciting phase, although there is some danger that progress may be stifled through the use of inappropriate preconceptions and analogies. It also shows that the impressive amount of evidence indicating that wet-canopy evaporation can exceed the net radiant energy by a large amount is by no means conclusive and that the research needed to remedy this situation would be much easier and less expensive than the research needed to identify and study an as yet unknown or underestimated source of energy.