Vegetation Canopy Reflectance Models.

Stochastic and deterministic approaches to simulating the spectro reflectance of shortgrass prairie vegetation have been investigated. The stochastic approach uses randomly selected variates for incoming light flux, plant geometry, and intrinsic optical properties whereas the deterministic model is patterned after the familiar Kubelka-Munk theory for diffuse reflectance. The model results are compared with field and laboratory measurements of Blue grama Bouteloua gracilis and successfully predicts the non-Lambertian character of the canopy. The site of the field measurements was the Pawnee National Grasslands, the intensive study site of the International Biological Program. Direct solar and diffuse sky irradiance and the optical properties of Blue grama were measured in the 0.4 micrometer to 1.05 micrometers region of the spectrum using a field adapted EG and G spectroradiometer with a computer based digital acquisition system. Canopy geometry was measured with a laboratory photographic technique with subsequent digitization of the profile images. Modified author abstract