Date of Graduation
Eberly College of Arts and Sciences
Richard B Thomas
Land conversion and industrial pollution are two of the most influential vehicles for anthropogenic perturbation of natural terrestrial processes and both have increased dramatically over the course of the last century. This research explores the role of Central Appalachian hardwood forests in the global carbon (C) balance during a century of regeneration with changing land use and atmospheric pollution. Most of the forests in this region were logged in the early 1900s. During the century the followed, nitrogen (N) deposition rates became especially high in parts of Central Appalachia where an increasing number of regenerated mature forests are now undergoing N saturation. I explored the effects of N saturation on processes that control productivity using a model that I modified to reflect conditions associated with Stage 2 of N saturation. I then applied the model to forests that have experienced different harvest histories during the last century of forest re-growth. I found that carefully planned harvests, such as diameter-limit cutting and single tree selection cutting, can stimulate ecosystem productivity by as much as 37%. To determine the regional contribution of mature forests to atmospheric C sinks, I assessed the spatial variability of foliar and soil N concentrations and applied the validated productivity model to sites across the state of West Virginia. Generally, I found that over the century of regeneration following harvest, forests in the Central Appalachian region sequestered an average of 4 to 5 Tg C yr -1. The modeled estimate of carbon storage is stimulated up to 20% by N saturation, a process that varies in intensity across the state and may be correlated with a transition in tree species composition. Loss of these forests would add about 300 Tg C to the atmosphere that would take another century to recover.
Davis, Sarah C., "Productivity and carbon budgets of harvested Central Appalachian forests" (2007). Graduate Theses, Dissertations, and Problem Reports. 4295.