The Response of Transpiration Resistance to Leaf Temperature as a Desication Resistance Mechanism in Tree Seedlings.

Transpiration rate and leaf transfer resistance to water vapor loss were determined under a range of leaf temperatures for Quercus macrocarpa, Q. velutina, Q. alba, Q. rubra, and Acer saccharum. Transfer resistance increased with rising leaf temperatures between 20 and 40°C in all species, but the rate of increase in resistance was greatest in species which normally occupy xeric sites. Increased transfer resistance with rising leaf temperature may be significant in preventing rapid desiccation of leaves under the large evaporative stress posed by high leaf temperature.