Needle-air temperature differences of Douglas-fir seedlings and relation to microclimate.

Abstract

Needle temperatures of Pseudotsuga menziesii seedlings on 3 exposed sites in SW Oregon remained within 3oC of air temperature under conditions of cloudless skies in late summer. Needle-air temperature differentials were positive during the day, negative at night, and were nonlinearly related to air temperature. This nonlinear relation is discussed qualitatively with respect to the influence of changes in net radiation, vapor pressure deficit, windspeed, and stomatal resistance occurring throughout the day.-Authors