A new approach to derive canopy structure information for boreal forests using spectral BRDF data

The spectral variability of BRDF effects in vegetation canopies was investigated with the anisotropy index (ANIX) and a normalized difference anisotropy index (NDAX). Both indices were related to the canopy structural properties of six dominant cover types in the Canadian boreal forests. High ANIX and NDAX values were associated with erectophile canopies such as black spruce. Planophile canopies, such as fen areas, exhibited low ANIX and NDAX values. Compared to nadir reflectance data and the normalized difference vegetation index (NDVI), the two new indices significantly improved the accuracy of land cover classification.