FOREST ENTOMOLOGY Development of a Satellite-Based Hazard Rating System for Dendroctonus frontallis (Coleoptera: Scolytidae) in the Ouachita Mountains of Arkansas

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae), is themost damaging forest insect pest of pines (Pinus spp.) throughout the southeasternUnited States. Hazard rating schemes have been developed for D. frontalis, but for these schemes to be accurate and effective, they require extensive on-site measurements of stand attributes such as host density, age, and basal area.We developed a stand hazard-rating scheme for several watersheds in the Ouachita Highlands of Arkansas based upon remotely sensed data and a geographic information system.Ahazardmodelwas developedusing stand attributes (tree species, stand age anddensity, pine basal area, and landform information) and was used to establish baseline hazard maps for the watersheds. Landsat 7 ETM data were used for developing new hazard maps. Two dates of Landsat imagerywere used in the analyses (August 1999 andOctober 1999). The highest correlations between hazard rating scores and remotely sensedvariables fromeitherof thedates included individualLandsat 7 ETM bands in the nearand mid-infrared regions as well as variables derived from various bands (i.e., Tasseled cap parameters, principal component parameters, and vegetation indices such as the calculated simple ratio and normalized difference vegetation index). Best subset regression analyses produced models to predict stand hazard to southern pine beetle that consisted of similar variables that resembled but were more detailed than maps produced using inverse distance weighted techniques. Although the models are speciÞc for the study area, with modiÞcations, they should be transferable to geographically similar areas.