Estimating foliar biochemistry from reflectance and the detection of phellinus sulphurascens induced stress

Photosynthetic pigments are frequently cited as one of the most responsive indicators of vegetation stress. This study estimated pigment content from needle reflectance and characterized the sensitivity of these pigments to a fungal-mediated stress. Samples were collected from the Greater Victoria Watershed District on Vancouver Island, BC, Canada. Lab reflectance measurements were made and pigments were extracted. Reflectance spectra were transformed to derivatives and a continuum removal band depth analysis was conducted. Reflectance metrics were generated and used in modeling pigment content. The predictive power of reflectance attributes were assessed and yielded exceptionally strong coefficients of determination (R²>0.80). Samples exhibiting stress responses affected by root disease were discriminated. It was determined that younger trees were more severely affected by the root pathogen than mature colonized trees.