Semester

Summer

Date of Graduation

2023

Document Type

Thesis

Degree Type

MA

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Brenden McNeil

Committee Co-Chair

Edward Brzostek

Committee Member

Amy Hessl

Abstract

Forests have long been recognized for their provision of air and water quality ecosystem services to society; but more recently, they have become valuable to the carbon credit markets used as a tool for mitigating climate change. Quantifying above ground carbon storage in forest ecosystems is essential for these carbon credit markets and can also provide insight into factors that control the spatial distribution of carbon in forests. The goal of this study is to assess the degree to which three factors: topography, tree species, and legacies of logging, impact the spatial variability in above ground carbon within a 400x500m Appalachian forest plot. Field work spanning 2018 to 2022 resulted in 14,932 surveyed trees with 27 unique tree species, totaling an estimated 2,107,736 kg of above ground carbon content. I used a multiple linear regression model to determine that 14% (Adjusted R2 = 0.14) of the spatial variability in above ground carbon can be explained by variables representing the three factors included in this study. Tree species, represented by their varying wood densities, explained the most variability (Std Beta = 0.39). Potential Evapotranspiration (PET), a variable summarizing the impact of topography on solar radiative plant water demand, was the second strongest (Std Beta = -0.18). Logging has a direct impact on the amount of above ground carbon content; however, the indirect effect of increased abundance of tree species with lower wood density in more recently harvested stands effectively captured this driver of forest carbon within the statistical model. This study highlights the interacting factors that simultaneously control the spatial variability of above ground carbon, and their impact on long-term carbon storage. For instance, in finding that most of the above ground carbon in the plot is in the dense wood of overstory oak species, and not in the less dense wood of the red maple-dominated understory that will likely replace the oaks over time, this study highlights how the “mesophycation” of eastern North American forests toward species like red maple may negatively affect aboveground forest carbon, and thus the carbon market value of this and similar Appalachian forests. To build on this baseline survey and spatial analysis of carbon stocks in this large Appalachian forest plot, we suggest that additional work can measure rates of aboveground carbon sequestration by repeating the tree census, and by working to identify spatial relationships with below ground carbon.

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