Abstract

The specular reflectance of a leaf is unrelated to wavelength or leaf content. However, a vegetation canopy is not a large leaf and specular reflectance is likely to be related to wavelength and vegetation amount because of the correlation between canopy geometry and vegetation amount. It was hypothesised that if the specular component were removed from the total (specular and diffuse) reflectance of a canopy then the strength of the correlation between diffuse reflectance and vegetation amount would decrease in near-infrared wavelengths and increase in visible wavelengths. Field based measurements of grassland using a polarising radiometer verified this hypothesis. It was recommended that where possible the specular component of the total reflectance be determined, at least in visible wavelengths, prior to the estimation of vegetation amount.