Relationship between stem density and dry-canopy evaporation rates in coniferous forests

Our previous study summarized published data on dry-canopy evaporation in coniferous forests during the growing season and found a decrease in the Priestley-Taylor coefficient (alpha) with canopy height. We speculated that the decrease in (alpha) was caused by a decrease in stomatal conductance with tree height. However, the decrease in (alpha) may also be explained by changes in leaf area index (LAI) and/or stem density with canopy height. We found no clear relationship between LAI and (alpha) in our previous study. Here, we examined the relationship between stem density and (alpha) and found no clear relationship, indicating that the decrease in (alpha) with increasing canopy height is not explained by changes in stem density. Thus, our results support the previous speculation that decrease in (alpha) was caused by a decrease in stomatal conductance with tree height.