Author ORCID Identifier

https://orcid.org/0000-0002-0627-0656

Date of Award

2026

Document Type

Thesis (Ph.D.)

Department or Program

Ecology, Evolution, Environment and Society

First Advisor

Caitlin Hicks Pries, Ph.D.

Second Advisor

Francis Magilligan, Ph.D.

Third Advisor

Shersingh Joseph Tumber-Dávila, Ph.D.

Abstract

Climate change factors act on the soil environment in complex ways, known to disturb soil organic carbon (C). Rising global temperatures and alterations to regional precipitation and nitrogen deposition regimes may contribute to the intensification of global change by accelerating the rate of biological decomposition and CO2 efflux to the atmosphere. The magnitude and endurance of the disturbance to soil organic C across landscapes and throughout time that climate change factors may pose to soil C cycling are not comprehensively understood. These knowledge gaps in our field make it challenging to anticipate how soil environments and the vast ecosystems that sit atop them may change over decades to millennia. In this thesis, I combine methods from in situ observation and experimentation to understand the consequences of past hydrological processes and future climate change conditions on soil organic C storage and cycling mechanisms in the forest soils of the northeastern United States (NE US). First, I demonstrate that prolonged manipulation with global change treatments, soil warming, and nitrogen (N) deposition has increased CO2 production rates in the subsurface soil of a mixed forest more than a decade after the treatments were initiated. Second, I demonstrate that forest soils subjected to 8 years of growing season warming and artificial wintertime freeze-thaw cycles (FTCs) had less soil organic matter (SOM), particularly in the mineral horizon, than soils subjected only to growing season warming, indicating that FTCs are detrimental to SOM in the subsurface. Finally, I demonstrate that the environmental variables most important for regulating SOM concentration and CO2 production vary across forested upland landscape positions. Together, these findings help elucidate how soil C responds to environmental and climate change factors over space and time and highlight the emerging importance of topographic metrics and mineral soil processes in soil C cycling.

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