Land use and terrestrial carbon storage in Western North Carolina from 1850-2030: a historical reconstruction and simulation study.

Abstract

The Southern Appalachian Mountains have experienced large and dynamic land-use changes since arrival of Euro-American settlers in the late 18th and early 19th centuries. Following transfer of the land from Native American societies, successive waves of immigration, development, resource extraction, and abandonment have driven land use over the past 200 years. There are large uncertainties regarding the timing and magnitude of these changes, and as a result, there are large uncertainties on the effects these land use legacies have on ecological processes and services. This dissertation addresses these uncertainties by quantifying and spatializing land use in the region since 1850, forecasting land use through 2030, and evaluating the effects of land-use change on the storage of carbon in terrestrial forest ecosystems. The study area is the 21-county region of Western North Carolina that is part of the Blue Ridge physiographic province. Macon County, NC, and four watersheds within Macon County are used as detailed case studies. Decadal land use patterns were reconstructed using sparse spatial data derived from historic maps, aerial photographs, and satellite imagery, more frequent tabular estimates of land use from census data, and terrain-based geospatial models. Carbon accrual in aboveground woody biomass was estimated from yield models and applied across the landscape using terrain-based estimates of site quality. Within Macon County, timber harvest and agriculture area peaked during 1900-1910, and following recovery, total forest area peaked from 1960-1980. Since 1950, the total development footprint has tripled, with over 2/3 of new houses expanding into areas that were predominantly forested. Across the region, total agriculture and forest area are forecasted to decline 12% and 5%, respectively, by 2030 as development expands. Carbon in aboveground woody biomass decreased an estimated 80% between 1850 and 1930, from an average of 201 Mg ha-1 in 1850 to a low of 40 Mg ha-1 in 1930, with 84% of this loss due to industrial logging and 16% due to agriculture expansion. Since 1930, the forests have been aggrading carbon at a decreasing rate of 24% per decade in 1940 to 5% per decade since 1990. Although total forest area will decrease 4%, carbon storage is forecasted to increase 10% by 2030 assuming no large disturbance.