Cooperative Fish and Wildlife Research Units Program: Virginia
Education, Research and Technical Assistance for Managing Our Natural Resources

The northern hardwood forest type is an important habitat component for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus) for den sites and corridor habitats between boreo-montane conifer patches where the squirrel forages. Our study related terrain data to patterns of occurrence for the northern hardwood forest type in the recovery areas of CNFS in the southern Appalachian Mountains of western North Carolina, eastern Tennessee, and southwestern Virginia to create a more robust, spatially predictive model of this forest type. We recorded overstory species composition, as well as terrain variables at 338 points to construct our predictive model. Terrain variables we examined included: elevation, aspect, slope gradient, curvature, and landform index. We used an information-theoretic approach to assess seven models based on associations noted in existing literature as well as an inclusive global model. Our results indicate that on a regional, multi-state scale, elevation, aspect, and landform index (TEI) for an area are significant predictors of the presence of the northern hardwood forest type in the southern Appalachians. Our Elevation + TEI model was the best approximating model (lowest AICc score) for predicting northern hardwood forest type. We correctly classified approximately 78% of our sample points as northern hardwoods. We then used these data to create region-wide predictive maps of the distribution of the northern hardwood forest type within CNFS recovery areas.