Hyperspectral Remote Sensing of Mountain Pine Beetle with an Emphasis on Previsual Assessment

. A study was undertaken to examine the spectral properties of trees infected by mountain pine beetle (Dendrotonus ponderosae, Hopkins) in central British Columbia. A monoculture pine forest infected with mountain pine beetle was flown in early autumn (September), with a repeat flight the following summer (July). High spatial/spectral resolution VNIR-SWIR and discrete LiDAR data were collected. Three states were recognized: healthy, previsual green attack, and red attack. Spectra from the September flight were sampled from positions derived from LiDAR-modeled treetops. Analysis focused primarily on 3 absorption features: pigment feature (685nm), and 2 water absorption features (970nm and 1200nm). Derivative- and depth-normalized continuum removed (CR) spectra were generated for all 3 classes. Results obtained suggest that consistent differences in the shape of the pigment absorption feature are observed among the healthy, green, and red attack samples. The results of the analyses of the water features were less conclusive. The 970nm feature did not show any separation, whereas the 1200nm showed significant separation with the derivative and CR curves. These results indicate that, although subtle, reflectance differences between healthy and green attack crowns might provide a means for early detection of mountain pine beetle attack.