Skip to main content
U.S. flag

An official website of the United States government

Sean Cahoon

Sean Cahoon
Research Ecologist
Resource Monitoring and Assessment
161 E 1st Ave.
Anchorage, AK 99501-1639
United States
Current Research

Understanding spatial patterns of forest carbon, and the temporal trends and drivers of tree growth are the primary focus areas of my research. I investigate the role forests play in the complex feedback between ecosystems and the global climate system, with a geographic focus on the forests of Alaska. The spatially balanced sampling design of the Forest Inventory and Analysis (FIA) program provides unique insight into broad-scale patterns of forest carbon pools and how they change over time. I am particularly interested in the large and climate-sensitive pool of belowground carbon in boreal forests, and leveraging the FIA network to investigate long-term changes in tree growth using tree-ring analysis. Annually resolved radial tree growth data from a wide range of forest conditions provides a wealth of opportunities to address pressing dendroecological questions, such as the relative importance of biotic and abitiotic drivers of tree growth, and the interaction between disturbance and climate. I approach my investigations through the lens of ecophysiology, as I seek to deepen our understanding of ecosystem function in a changing world.

Past Research
My previous research had a broad focus on ecosystem carbon cycle processes in response to mutliple biotic and abiotic drivers of changes in arctic shrub communities. Specifically, I investigated the interaction between herbivory (caribou and muskoxen) and warming on ecosystem CO2 flux and used a space-for-time experiment to address how shrub expansion may alter spatiotemporal patterns in ecosystem-atmosphere CO2 exchange. I also quantified the absolute and relative proportions of belowground heterotrophic and autotrophic respiration from various arctic tundra communities. My dendroecological investigations include methodological comparisons of detrending techniques, comparing growth trends of common tree species in boreal and temperate forests, and broadening dendorecological inquiries to include disturbance and site-level factors, in addition to climatic controls.
Research Interest
  • Spatial patterns of forest carbon pools
  • Dendroecological investigations of long-term trends and drivers of tree growth
  • Forest ecophysiology and carbon-climate feedbacks in response to climate change
  • Penn State University, Ph.D, Ecology, 2015
  • University of Alaska Anchorage, Master Of Science, Biology, 2010
  • University of Alaska Anchorage, B.S, Natural Science, 2006
Awards & Recognition
  • PNW Station Director's Early Career Scientist Award, 2020
  • PNW Extra Effort Station Award, 2020
    Significant contributions to science development and leadership, external collaborator outreach, and data quality evaluation and documentation for the FIA Interior Alaska Forest Inventory project.
  • Reseach and Development Deputy Chief's Early Career Scientist Award, 2020
Featured Publications
Other Publications
Citations of Non-Forest Service Publications
  • Patrick F. Sullivan, Annalis H. Brownlee, Sarah B.Z. Ellison and Sean M.P. Cahoon (2021). Comparative drought sensitivity of co-occuring white spruce and paper birch in interior Alaska. Journal of Ecology,

    Eric Post, Sean M.P. Cahoon, Jeffrey T. Kerby, Christian Pedersen, Patrick F. Sullivan (2021). Herbivory and warming interact in opposing patterns of covariation between arctic shrub species at large adn local scales. Proceedings of the National Academy of Sciences, 118: e2015158118.

    Sean M.P. Cahoon, Olaf Kuegler and Glenn Christensen (2020). Coastal Alaska’s Forest Resources, 2004-2013: Ten-year Forest Inventory and Analysis Report. PNW-GTR-979. USDA Forest Service, Pacific Northwest Research Station. Anchorage, AK. 

    Sarah B.Z. Ellison, Patrick F. Sullivan, Sean M.P. Cahoon and Rebecca Hewitt (2019). Poor nutrition as a potential cause of divergent tree growth in the Brooks Range, Alaska. Ecology. 100(12):e02878.

    Sean M.P. Cahoon, Patrick F. Sullivan, Annalis H. Brownlee, Robert R. Pattison, Hans-Erik Andersen, Kate Legner and Teresa N. Hollingsworth (2018). Contrasting drivers and trends of coniferous and deciduous tree growth in interior Alaska. Ecology. 99: 1284-1295.

    Patrick F. Sullivan, Robert R. Pattison, Annalis H. Brownlee, Sean M.P. Cahoon and Teresa N. Hollingsworth (2017). Limited evidence of declining growth among moisture-limited black and white spruce in interior Alaska. Scientific Reports. 7: 15344.

    Patrick F. Sullivan, Robert R. Pattison, Annalis H. Brownlee, Sean M.P. Cahoon and Teresa N. Hollingsworth (2016). Effect of tree-ring detrending method on apparent growth trends of black and white spruce in Interior Alaska. Environmental Research Letters, 11: 114007.

    N. John Anderson, Jasmine E. Saros, Joanna E. Bullard, Sean M.P. Cahoon, et al. (2017). The Arctic in the 21st century: Changing biogeochemical linkages across a paraglacial landscape in Greenland. BioScience, 67: 118-133.

    Sean M.P. Cahoon, Patrick F. Sullivan and Eric Post (2016). Greater abundance of Betula nana and advanced spring phenology increase ecosystem CO2 uptake in West Greenland. Ecosystems, 19: 1149-1163.

    Sean M.P. Cahoon, Patrick F. Sullivan and Eric Post (2016). Carbon and water relations of contrasting Arctic plants: implications for shrub expansion in West Greenland. Ecosphere, 7: doi:10.1002/ecs2.1245.

    Sean M.P. Cahoon, Patrick F. Sullivan, Cassandra Gamm, Jeffrey M. Welker, David Eissenstat and Eric Post (2016). Lack of variation in proportional contributions of auto- and heterotrophic soil respiration, despite large differences in vegetation structure and function at a low-Arctic site. Biogeochemistry, 127: 339-351.

    Sean M.P. Cahoon, Patrick F. Sullivan, Gaius R. Shaver, Jeffrey M. Welker and Eric Post (2012). Interactions among shrub cover and the soil microclimate may determine future Arctic carbon budgets.  Ecology Letters, 15: 1415-1422.

    Sean M.P. Cahoon, Patrick F. Sullivan, Eric Post and Jeffrey M. Welker (2012). Large herbivores limit CO2 uptake and suppress carbon cycle responses to warming in West Greenland. Global Change Biology, 18: 479-479.