Variability and covariance of factors affecting canopy reflectance within a 6 ha corn field

The variability of factors affecting landscape reflectance are of interest for remote sensing validation experiments, remote sensing parameter retrieval efforts, and plant canopy simulation studies among others. Leaf optical properties and foliage density, expressed as leaf area index (LAI) are significant factors affecting canopy reflectance. Canopy height can be important when using a 3-dimensional simulation model. Variations in these elements cause variations in field-scale canopy reflectance although detailed measurements on scales larger than individual plots are rare. These factors are also usually treated as independent. However each is a function of plant vigor and thus should exhibit some covariance. Measurements of these factors at 64 locations within a 6 ha corn field were made at the Beltsville Agricultural Research Center, Beltsville, MD during July and August, 1997. The August data were collected after onset of a drought. The ranges of values for the factors are examined and covariance among the factors are examined. Results show a slight positive trend between LAI and height. A positive relationship between leaf reflectance and transmittance is noticeable for 501 nm, 550 nm, 601 nm and 702 nm, although not 1:1. There are also trends between leaf reflectance and transmittance, and LAI