Studies on Leaf Characteristics of a Cline of Eucalyptus urnigera From Mount Wellington, Tasmania. II. Reflection, Transmission and Absorption of Radiation.

Abstract

Coefficients of reflection of green and glaucous leaves of Eucalyptus urnigera were, respectively, 26 % and 40% for total radiation and 13% and 30% for visible radiation. Transmission coefficients varied only slightly between leaves differing in glaucousness, being about 24 % and 6% for total and visible radiation respectively. These properties resulted in coefficients of absorption of total radiation varying from 50% for green leaves to 37% for glaucous leaves and of visible radiation from 82% to 66 %.

The coefficients for total radiation were measured by means of a hemispherical integrating radiometer and those for radiation over the wave band of 350-1350 nm by means of a spectrophotometer. There was good agreement between the two methods.

The differences in these spectral properties between the two leaf types are attributed to diffuse reflection by the wax crystals on the surface of the glaucous leaf.