Visible-near infrared spectral reflectance of landscape components in western Oregon

Abstract

To help interpret satellite-derived measures of spectral vegetation indices across western Oregon, we collected samples of important landscape constituents and determined their spectral reflectance properties using a Spectron Engineering field spectrometer. To make measurements reproducible, we created stacks of branches and other materials in well-illuminated areas and continually referenced measurements against a standard reference panel. The measurements indicated that variations in remotely sensed spectral vegetation indices observed in western Oregon originate from variations in both canopy spectral optical properties and background spectral reflectance rather than simple variations in leaf area index or percentage canopy closure. This suggests that satellite-derived changes in spectral vegetation indices may not be easily interpretable in terms of vegetation physiognomic properties at regional and global scales. Further studies of regional landscape component spectral reflectance properties are recommended to refine interpretation of remotely sensed vegetation indices.