Informing Red Spruce (Picea rubens) Restoration in the Mount Rogers Highlands, VA, USA Through Geospatial Analysis and Modeling of Soil Properties

Abstract

Southern Appalachian red spruce (Picea rubens) forests are globally rare, endangered, and disjunct ecosystems. These forests, which often contain Fraser fir (Abies fraseri) as an associate conifer, provide habitat for endemic and endangered species, have local cultural and economic value, and are highly valued by outdoor recreationalists. This thesis explored opportunities for restoration in a red spruce-Fraser fir forest in southwest Virginia, known as the Mount Rogers Highlands (MRH). The MRH includes Mount Rogers, the highest point in Virginia, and Grayson Highlands State Park. By performing geospatial analyses of vegetation, topographic, climate, land cover, and land-use history raster data, we targeted sites for restoration that intersected high priority restoration locations and spaces with the highest potential of reconnecting extant forest fragments, based on a least-cost path analysis. We identified restoration techniques that will be most successful in regions we targeted as best suited for restoration. Our analyses suggested that 11.2 km² is suitable for restoration in the MRH, twice the area than is currently dominated by red spruce, pointing to a high potential for restoration. Additionally, this thesis investigated the relationship between spruce canopy and vertical soil chemistry profiles in the MRH to better understand whether red spruce restoration may induce a positive feedback for future spruce regeneration and seedling survival. Using a linear mixed-effects modeling framework, we demonstrated that increased spruce canopy in the MRH is associated with significant shifts in soil aluminum and iron content, soil organic matter, and soil pH. Such shifts may have ecologically meaningful implications for current restoration guidelines and for future impacts of red spruce restoration. This thesis and research therein contributed to the body of knowledge surrounding red spruce restoration during a critical time for the species' restoration and longevity and provides recommendations for future restoration actions.