VISIBLE-NEAR-INFRARED SPECTRAL REFLECTANCE OF LANDSCAPE COMPONENTS INWESTERN OREGON

To help interpret satellite-derived measures of spectral vegetation in dices across western Oregon, we collected samples of important landsca pe constituents and determined their spectral reflectance properties u sing a Spectron Engineering field spectrometer. To make measurements r eproducible, we created stacks of branches and other materials in well -illuminated areas and continually referenced measurements against a s tandard reference panel. The measurements indicated that variations in remotely sensed spectral vegetation indices observed in western Orego n 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 satel lite-derived changes in spectral vegetation indices may not be easily interpretable in terms of vegetation physiognomic properties at region al and global scales. Further studies of regional landscape component spectral reflectance properties are recommended to refine interpretati on of remotely sensed vegetation indices.