ENVIRONMENTAL INFLUENCES ON SPECTRAL REFLECTANCE AND OLEORESIN CHEMISTRY OF CONIFERS, MAMMOTH MOUNTAIN TREE KILL AREAS, CALIFORNIA

Sampling and analysis of lodgepole and white bark pines to evaluate the relationship between oleoresin chemistry and spectral reflectance changes as a function of plant health were completed at the Horseshoe Lake (HSL) and other tree kill areas around Mammoth Mountain, California during the Fall of 2000 and 2001. Both review of the literature and the analysis of our HSL dataset indicate that each variable undergoes a series of changes that relate not only to the health state but also the nature of the impact (i.e., biotic vs. abiotic, etc.). Analysis of the 2000 dataset included identification of a series of absorption features and monoterpene compositions that discriminate between the two end-member health states (healthy versus dying/dead). Several of the adsorption features (e.g., 1730, 2100 and 2300 nm) fall within spectral regions typically associated with olefinic hydrocarbons such as the monoterpenes. Covariance and regression analysis between the absorption features and monoterpene concentration shows that a statistically significant model exists that also separates the healthy from dying/dead end-members of the conifers.

Preliminary analysis of the 2001 dataset shows similar covariance between adsorption features and monoterpene concentration. Additional correspondence with the spectral features, monoterpene composition and environmental factors such as herbivory, water deficit and differences in geochemical substrate are apparent and will be discussed.