Spectral Characterization of Biophysical Characterstics in a Boreal Forest: Relationship between Thematic Mapper Band Reflectance and Leaf Area Index for Aspen

Initial results from analysis of a data set of simultaneous measurements of Thematic Mapper band reflectance and leaf area index are presented. The measurements were made over pure homogenous stands of Aspen in the Superior National Forest of northern Minnesota. The analysis indicates that the reflectance may be sensitive to the leaf area index of the Aspen early in the season. The sensitivity disappears as the season progresses. Based on the results of model calculations, a possible explanation for the observed relationship is developed. The model calculations indicate that the sensitivity of the reflectance to the Aspen overstory is dependent on the amount of understory present.