Leaf temperatures of alpine plants in the field

1. Leaf temperatures of Colorado alpine plants on Mount Evans (4300 m) and near the Trail Ridge Road (3800 m) were measured along with air temperature, wind velocity, maximum and zenith light intensities, net radiation, and in one study humidity. 2. When skies were clear above Mount Evans, plant temperatures were clearly dependent upon insolation, being as much as 22° C above ambient. Under uniformly cloudy skies, plant temperatures did not deviate far from air temperatures. 3. Under typically fluctuating alpine conditions, correlations between leaf temperature and certain environmental factors are imperfect. Failure of the correlation is ascribed to factors not measured, mechanics of the analysis, changing environment, and position effects. 4. Application of these findings to controlled environment (growth chamber) studies poses an interesting and inherently difficult problem.