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Emily K. Heyerdahl

Research Forester

5775 Highway 10 West
Missoula, MT 59808-9361
Contact Emily K. Heyerdahl

Current Research

  • Historical fire regimes in mixed-conifer forests of Central Oregon
  • Historical fire regimes in Utah
  • Historical fire regimes in mixed-conifer forests of the Flathead Valley, Montana
  • Condition of live, fire-scarred ponderosa pine trees 21 years after removing fire-scarred partial cross sections

Research Interests

Heyerdahl's research focuses on inferring the drivers of spatial and temporal variation in fire regimes over the past several centuries using tree rings and modern fire records. These drivers include climate, forest type, topography, and land use.

Past Research

  • Spatial and temporal varation of historical fires in the Blue Mountains, Oregon
  • Climate drivers of fire in the Northern Rockies: Past, present and future
  • Historical mixed-severity fire regimes in British Columbia, Canada
  • Climatic and human influences on historical fire regimes of Mexico
  • Fire history of Interior West Sagebrush Woodlands

Why This Research is Important

This research impacts both forest management and our understanding of basic forest and fire ecology. The National Fire Plan, the Federal Wildland Fire Management Policy, and the Forest Service's Cohesive Strategy clearly identify the need to restore frequent-fire forests by treating fuel. Knowledge of past fire regimes, how and why they varied across space, and how they affected forest structure and composition provides a basis for prescribing fuel treatments that mimic the effects of past fires, while knowledge of the climate forcing of extreme fire years provides a basis for scheduling such treatments. Spatially explicit reconstructions of fire regimes can be used to identify fundamental properties of those regimes, such as the scaling properties of fire frequency. Knowledge about the drivers of spatial and temporal variation in historical fire regimes is used by other scientists to parameterize, and validate simulation models, for example to predict the effects of climate change on future fire regimes. Anticipating the effects of climate change on future fire requires that we understand the effects of climate variation on past fires using tree rings and also that we bridge the past and the present by identifying the climate drivers of 20th-century fires from written archival records.


  • Oregon State University, Corvallis, OR, B.S., Geology, 1985
  • University of Washington, M.S., Atmospheric Sciences, 1991
  • University of Washington, Ph.D., Forestry, 1997
  • Professional Organizations

    • Association for Fire Ecology, Member ( 2006 to present )
    • Ecological Society of America, Member ( 1995 to present )
    • Tree-Ring Society, Lifetime Member ( 1991 to present )

    Featured Publications


    Harley, Grant L.; Baisan, Christopher H.; Brown, Peter M.; Falk, Donald A.; Flatley, William T.; Grissino-Mayer, Henri D.; Hessl, Amy; Heyerdahl, Emily K.; Kaye, Margot W.; Lafon, Charles W.; Margolis, Ellis Q.; Maxwell, R. Stockton; Naito, Adam T.; Platt, William J.; Rother, Monica T.; Saladyga, Thomas; Sherriff, Rosemary L.; Stachowiak, Lauren A.; Stambaugh, Michael C.; Sutherland, Elaine K.; Taylor, Alan H., 2018. Advancing dendrochronological studies of fire in the United States
    Merschel, Andrew G.; Heyerdahl, Emily K.; Spies, Thomas A.; Loehman, Rachel A., 2018. Influence of landscape structure, topography, and forest type on spatial variation in historical fire regimes, Central Oregon, USA
    Daniels, Lori D.; Kent, Larissa L. Yocom; Sherriff, Rosemary L.; Heyerdahl, Emily K., 2017. Deciphering the complexity of historical fire regimes: Diversity among forests of western North America [Chapter 8]
    Hood, Sharon M.; Sala, Anna; Heyerdahl, Emily K.; Boutin, Marion, 2015. Low-severity fire increases tree defense against bark beetle attacks
    Merschel, Andrew G.; Spies, Thomas A.; Heyerdahl, Emily K., 2014. Mixed-conifer forests of central Oregon: Effects of logging and fire exclusion vary with environment
    Morgan, Penelope; Heyerdahl, Emily K.; Miller, Carol L.; Wilson, Aaron M.; Gibson, Carly E., 2014. Northern Rockies pyrogeography: An example of fire atlas utility
    Cohn, Gregory M.; Parsons, Russell A.; Heyerdahl, Emily K.; Gavin, Daniel G.; Flower, Aquila, 2014. Simulated western spruce budworm defoliation reduces torching and crowning potential: A sensitivity analysis using a physics-based fire model
    Flower, Aquila; Gavin, Daniel G.; Heyerdahl, Emily K.; Parsons, Russell A.; Cohn, Gregory M., 2014. Western spruce budworm outbreaks did not increase fire risk over the last three centuries: A dendrochronological analysis of inter-disturbance synergism
    Matonis, Megan; Luce, Charles H.; Holden, Zack; Morgan, Penny; Heyerdahl, Emily K., 2013. Science You Can Use Bulletin: Our forests in the [water] balance
    Heyerdahl, Emily K.; Brown, Peter M.; Kitchen, Stanley G.; Weber, Marc H., 2011. Multicentury fire and forest histories at 19 sites in Utah and eastern Nevada
    Cassell, Brooke A.; Alvarado, Ernesto; Heyerdahl, Emily K.; Perez-Salicrup, Diego; Jardel-Pelaez, Enrique, 2010. Climate change and fire regimes in the Sierra de Manantlan, Mexico
    Falk, Donald A.; Heyerdahl, Emily K.; Brown, P. M.; Swetnam, T. W.; Sutherland, Elaine K.; Gedalof, Z.; Yocom, L.; Brown, T. J., 2010. Fire and climate variation in western North America from fire-scar and tree-ring networks
    Brown, Peter M.; Heyerdahl, Emily K.; Kitchen, Stanley G.; Weber, Marc H., 2008. Climate effects on historical fires (1630-1900) in Utah
    Parsons, Russell A.; Heyerdahl, Emily K.; Keane II, Robert E.; Dorner, Brigitte; Fall, Joseph, 2007. Assessing accuracy of point fire intervals across landscapes with simulation modelling
    Shapiro-Miller, Lauren B.; Heyerdahl, Emily K.; Morgan, Penelope, 2007. Comparison of fire scars, fire atlases, and satellite data in the northwestern United States
    Kitzberger, Thomas; Brown, Peter M.; Heyerdahl, Emily K.; Swetnam, Thomas W.; Veblen, Thomas T., 2007. Contingent Pacific-Atlantic Ocean influence on multicentury wildfire synchrony over western North America
    Gayton, Don V.; Weber, Marc H.; Harrington, Mick; Heyerdahl, Emily K.; Sutherland, Elaine K.; Brett, Bob; Hall, Cindy; Hartman, Micahel; Peterson, Liesl; Merrel, Carolynne, 2006. Fire history of a western Montana ponderosa pine grassland: A pilot study
    The frequency of fire in low-elevation coniferous forests in western North America has greatly declined since the late 1800s. In many areas, this has increased tree density, increased the proportion of shade-tolerant species, reduced resource availability, and increased forest susceptibility to forest insect pests and high-severity wildfire. This study investigated how low-intensity fire affects tree defenses and whether fuel treatments impact resistance to a mountain pine beetle outbreak.
    Proper management of naturally forested landscapes requires an understanding of the temporal and spatial patterns in which key disturbance processes are manifest and their effects on species composition and structure. Linked fire and forest histories constructed from tree-ring evidence provide valuable information about drivers of fire occurrence and about the variability and interactions of fire regimes and vegetation on heterogeneous landscapes.
    Research Forester Emily Heyerdahl prepares samples for archiving (photo by Roger Pilkington).
    The Rocky Mountain Research Station is preparing more than 16,000 tree-ring specimens for permanent archiving. Each specimen is a unique record of the environmental conditions from which it came. This tree-ring specimen collection will be permanently archived at the only federally recognized tree-ring repository in the U.S., where its importance will grow as it is used in ways we cannot currently imagine.
    Evaluating effects of climate change on whitebark pine trees.
    The impact of fire on conifer defenses.
    Over the past 20 years, we have been monitoring mortality rates for ponderosa pine trees in the Blue Mountains of northeastern Oregon since we removed a fire-scarred partial cross-section from them. We suggest that sampling live, fire-scarred ponderosa pine trees remains an important and generally non-lethal method of obtaining information about historical fires that can supplement the information obtained from dead fire-scarred trees.
    In the interior West, western spruce budworm outbreaks often last for decades, but their impact on fire behavior is poorly understood. By isolating the effects of the insect on a single tree and simulating the tree in a three-dimensional fire model, researchers were able to identify precise links between western spruce budworm disturbance and fire behavior changes.
    Tree-rings are used to reconstruct fire and forest histories in central Oregon.

    National Strategic Program Areas: 
    Wildland Fire and Fuels
    National Priority Research Areas: 
    Forest Disturbances
    RMRS Science Program Areas: 
    Fire, Fuel and Smoke