Mapping upland hardwood site quality and productivity with GIS and FIA in the Blue Ridge of North Carolina

Abstract

The forested ecosystems of the southern Appalachians are some of the most diverse in North America due to the variability in climate, soils, and geologic parent material coupled with the complex topography found throughout the region. These same characteristics cause stands of upland hardwoods to be extremely variable with regard to site quality and productivity. Site index has been the tool most commonly used to measure existing site quality and productivity, but measured site index may not accurately quantify potential site quality and productivity, largely due to ubiquitous disturbance and variable land-use history. Because of this, environmental factors may hold merit in predicting the quality of a forested site in the southern Appalachians. To assess the accuracy of existing methods, three indices developed within the region were used to predict the site quality of the upland hardwood forests throughout a six-county study area in the Blue Ridge physiographic province of western North Carolina. We hypothesized that predictions of site quality generated by the indices would correlate with similar estimates from Forest Inventory and Analysis (FIA) plots. We also predicted that the indices that included multiple types of information would produce higher correlations with FIA estimates. Finally, we felt we would be able to reasonably predict site index, but not basal area or volume increment. The environment of the study area was derived from a layered GIS that depicted variables related to water availability. FIA data and actual plot locations were compared to the predictions. Results indicated a moderate correlation between one index and site quality. The index with multiple layers of information did not produce a higher correlation, and there was no relationship among any of the indices to basal area or volume increment. Future research will include finerscaled estimates of soil information and estimates of water inputs as well as usage.

Parent Publication

• Forest Inventory and Analysis (FIA) Symposium 2008; October 21-23, 2008; Park City, UT

Citation

Cotton, Claudia A.; Prisley, Stephen R.; Fox, Thomas R. 2009. Mapping upland hardwood site quality and productivity with GIS and FIA in the Blue Ridge of North Carolina. In: McWilliams, Will; Moisen, Gretchen; Czaplewski, Ray, comps. Forest Inventory and Analysis (FIA) Symposium 2008; October 21-23, 2008; Park City, UT. Proc. RMRS-P-56CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 13 p.