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Harvard Forest REU Symposium Abstract 2021

  • Title: Effects of Atmospheric Deposition on Carbon Sequestration in Temperate Forest Ecosystems
  • Author: Connor S Tamor (Cornell University)
  • Abstract:

    Since the industrial revolution, humans have increased atmospheric concentrations of greenhouse gases (GHGs), including carbon dioxide (CO2), methane, and nitrous oxide, which together lead to climate change. Forests currently store approximately 30% of CO2 emitted by human activities, so understanding the biogeochemical processes that cycle carbon (C) through forest ecosystems is crucial to combat increasing GHGs and climate change. While atmospheric N deposition and its effects on forest ecosystems have been well-studied, patterns and trends of atmospheric deposition of non-N compounds are less well known. Furthermore, few have studied the impact of these forms of atmospheric deposition on C sequestration in forest ecosystems. The two main questions we addressed include: (1) what patterns and trends exist in non-nitrogen atmospheric deposition over time and (2) how does atmospheric deposition affect C sequestration in Northeastern U.S. temperate forest ecosystems? Using publicly available atmospheric deposition data from the National Atmospheric Deposition Program (NADP), C flux data from Harvard Forest, and C flux and biomass data from Hubbard Brook, we ran several regression analyses to examine potential trends between atmospheric deposition and C sequestration over time. We found that, in general, non-nitrogen forms of atmospheric deposition have decreased over time. Rates of C sequestration at Harvard Forest have increased, while C sequestration at Hubbard Brook has remained stagnant over time. We also found that only calcium (Ca) atmospheric deposition may influence C sequestration, with positive relationships at Harvard Forest and inverse relationships at Hubbard Brook. These contrasting results suggest that Ca deposition is an important control on C sequestration in temperate forests, but not always in the same ways across different forest types. Further exploration of how Ca controls C sequestration will help us better predict how forests may or may not mitigate the adverse effects of climate change in the future.

  • Research Category: Soil Carbon and Nitrogen Dynamics; Group Projects; Forest-Atmosphere Exchange; Conservation and Management