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William M. Jolly

Research Ecologist

5775 US West Highway 10
Missoula, MT 59808
Contact William M. Jolly

Current Research

Dr. Jolly's research is focused in three main areas:

  1. Physiological controls of flammability in living plants
  2. Modeling wildland fire potential and behavior.
  3. Science delivery of spatial wildland fire potential information.

Recent Publications:

Jolly, W. Matt; Cochrane, Mark A.; Freeborn, Patrick H.; Holden, Zachary A.; Brown, Timothy J.; Williamson, Grant J.; Bowman, David M. J. S. 2015. Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications. 6: 7537.

Jolly, W. Matt; Hadlow, Ann M.; Huguet, Kathleen. 2014. De-coupling seasonal changes in water content and dry matter to predict live conifer foliar moisture content. International Journal of Wildland Fire. 23(4): 480-489.

Research Interests

Dr. Jolly's research interests are diverse but they generally focus in two primary areas: physiological controls of live plant combustion and fire danger assessment research.

Much is know about how fires ignite and spread through dead plant biomass but very little is known about how living plants burn. He is interested in describing the physiological constraints to live fuel flammability and better understanding how we can assess the fire potential in live vegetation. Most of the fires throughout the country happen in mixtures of living and dead plants, so it is important to understand the factors that lead to intense and / or rapidly spreading fires. If one can define the physiological criteria that lead to elevated flammability, one can better plan for and respond to wildland fires. Further, it is important to understand how these characteristics are altered when forests are disturbed by insects such as the Mountain Pine Beetle. This new knowledge is critical to providing managers the information they need to best manage public lands throughout the world.

Second, basic knowledge of the fire potential must be translated into metrics that fire managers can use for fire planning and wildfire response. Therefore his second main research interest revolves around modeling and mapping key factors that drive changes in wildland fire potential across landscapes. He has have developed models and systems that can use weather and fuels data to map changes in fire potential and we have made this information available to local, state and federal fire managers throughout the country through the Wildland Fire Assessment System.

Example Publications:

Jolly, W. Matt; Parsons, Russell A.; Hadlow, Ann M.; Cohn, Greg M.; McAllister, Sara S.; Popp, John B.; Hubbard, Robert M.; Negron, Jose F. 2012. Relationships between moisture, chemistry, and ignition of Pinus contorta needles during the early stages of mountain pine beetle attack. Forest Ecology and Management. 269: 52-59.

Past Research

Dr. Jolly's past work was more focused on global phenology and productivity. Particularly, he developed a globally-applicable model of vegetation foliar phenology that has been widely used in phenology and climate change research (Jolly et. al. 2005). Additionally, he leverage global vegetation and weather data to assess long-term changes in global land surface net primary productivity (Nemani et. al. 2003).

Further reading:
Nemani, R.R.;Keeling, C.D.;Hashimoto, H.; Jolly, W.M.;Piper, S.C.;Tucker, C.J.;Myneni, R.B.;Running, S.W.; 2003; Climate-Driven Increases in Global Terrestrial Net Primary Production from 1982 to 1999. Science 300(5625) 1560-1563. doi: 10.1126/science.1082750

Jolly, W.M.; Nemani, R.R.; Running, S.W.; 2005. A generalized, bioclimatic index to predict foliar phenology in response to climate. Global Change Biology 11(4) 619-632, doi:10.1111/j.1365-2486.2005.00930.x

Stockli, R.; Rutishauser, T.; Dragoni, D.; O'Keefe, J.; Thornton, P. E.; Jolly, M.; Lu, L.; Denning, A. S. 2008. Remote sensing data assimilation for a prognostic phenology model. Journal of Geophysical Research. 113: G04021, doi:10.1029/2008JG000781.

Why This Research is Important

Wildland fires are now more common and they burn more area than any time in the record past. New knowledge and new tools are needed to address these changing conditions. Dr. Jolly's research is at the forefront of science and is advancing our knowledge of the conditions lead to extreme and costly wildfires. His work has the potential to help address a critical knowledge gap that could improve our ability to manage landscapes for resilience.

Read more about why this work is needed:
Finney, Mark A.; Cohen, Jack D.; McAllister, Sara S.; Jolly, W. Matt. 2012. On the need for a theory of wildland fire spread. International Journal of Wildland Fire. International Journal of Wildland Fire. 22: 25-36.


  • University of Montana, Phd, Forestry, 2004
  • University of Virginia, Bachelor Of Arts, Environmental Sciences with emphasis in Ecology, 2000
  • Community College of the Air Force, Associates Of Applied Science, Electronic Systems Technologies, 1995
  • Professional Organizations

    • American Meteorological Society, Member ( 2005 to present )
      Fire and Forest Meteorology Meeting Planning Committee
    • American Geophysical Union, Member ( 2004 to present )
    • International Association of Wildland Fire, Member ( 2003 to present )
      Associate Editor - International Journal of Wildland Fire


    Paper of the Year, Environmental Modeling and Software, 2005
    Interdisciplinary Award, Dept of Environmental Science, University of Virgina, 2000
    Fellowship, Montana Space Grant Consortium, NASA, 2000
    Chamberlain Award, Dept of Environmental Science, University of Virgina, 1999
    Eagle Award for Academic Excellence, Aerospace Education Foundation, 1995
    Eagle Scout, 1990
    Troop 336, North Wilkesboro, NC

    Featured Publications


    Brown, Tegan P.; Hoylman, Zachary H.; Conrad, Elliott; Holden, Zachary; Jencso, Kelsey; Jolly, William M. , 2022. Decoupling between soil moisture and biomass drives seasonal variations in live fuel moisture across co-occurring plant functional types
    Freeborn, Patrick; Jolly, William M.; Cochrane, Mark A.; Roberts, Gareth , 2022. Large wildfire driven increases in nighttime fire activity observed across CONUS from 2003-2020
    Jimenez-Ruano, Adrian; Jolly, William M.; Freeborn, Patrick; Vega-Nieva, Daniel Jose; Monjaras-Vega, Norma Angelica; Briones-Herrera, Carlos Ivan; Rodrigues, Marcos , 2022. Spatial predictions of human and natural-caused wildfire likelihood across Montana (USA)
    Rapp, Claire E.; Wilson, Robyn S.; Toman, Eric L.; Jolly, William M. , 2021. Assessing the role of short-term weather forecasts in fire manager tactical decision-making: A choice experiment
    Poulter, Benjamin; Freeborn, Patrick; Jolly, William M.; Varner, J. Morgan , 2021. COVID-19 lockdowns drive decline in active fires in southeastern United States
    Varner, J. Morgan; Hood, Sharon M.; Aubrey, Doug P.; Yedinak, Kara; Hiers, J. Kevin; Jolly, William M.; Shearman, Timothy M.; McDaniel, Jennifer K.; O'Brien, Joseph J.; Rowell, Eric M. , 2021. Tree crown injury from wildland fires: Causes, measurement and ecological and physiological consequences
    Dillon, Gregory K.; Panunto, Matthew H.; ; Morgan, Penelope; Birch, Donovan S.; Jolly, William M. , 2020. Development of a Severe Fire Potential map for the contiguous United States
    Briones-Herrera, Carlos Ivan; Vega-Nieva, Daniel Jose; Monjaras-Vega, Norma Angelica; Briseno-Reyes, Jaime; Lopez-Serrano, Pablito Marcelo; Corral-Rivas, Jose Javier; Alvarado-Celestino, Ernesto; Arellano-Perez, Stefano; Alvarez-Gonzalez, Juan Gabriel; Ruiz-Gonzalez, Ana Daria; Jolly, William M.; Parks, Sean A. , 2020. Near real-time automated early mapping of the perimeter of large forest fires from the aggregation of VIIRS and MODIS active fires in Mexico
    Page, Wesley; Freeborn, Patrick; Butler, Bret W.; Jolly, William M. , 2019. A classification of US wildland firefighter entrapments based on coincident fuels, weather, and topography
    Page, Wesley; Freeborn, Patrick; Butler, Bret W.; Jolly, William M. , 2019. A review of US wildland firefighter entrapments: Trends, important environmental factors and research needs
    Briones-Herrera, Carlos Ivan; Vega-Nieva, Daniel Jose; Monjaras-Vega, Norma Angelica; Flores-Medina, Favian; Lopez-Serrano, Pablito Marcelo; Corral-Rivas, Jose Javier; Carrillo-Parra, Artemio; Pulgarin-Gamiz, Miguel Angel; Alvarado-Celestino, Ernesto; Gonzalez-Caban, Armando; Arellano-Perez, Stefano; Alvarez-Gonzalez, Juan Gabriel; Ruiz-Gonzalez, Ana Daría; Jolly, William M. , 2019. Modeling and mapping forest fire occurrence from aboveground carbon density in Mexico
    Jolly, William M.; Freeborn, Patrick; Page, Wesley; Butler, Bret W. , 2019. Severe Fire Danger Index: A forecastable metric to inform firefighter and community wildfire risk management
    Jimenez-Ruano, Adrian; Mimbrero, Marcos Rodrigues; Jolly, William M.; de la Riva Fernandez, Juan , 2019. The role of short-term weather conditions in temporal dynamics of fire regime features in mainland Spain
    Bowman, David M. J. S.; Daniels, Lori D.; Johnston, Fay H.; Williamson, Grant J.; Jolly, William M.; Magzamen, Sheryl; Rappold, Ana G.; Brauer, Michael; Henderson, Sarah B. , 2018. Can air quality management drive sustainable fuels management at the temperate wildland-urban interface?
    Holden, Zachary A.; Swanson, Alan; Luce, Charles H.; Jolly, William M.; Maneta, Marco; Oyler, Jared W.; Warren, Dyer A.; Parsons, Russell A.; Affleck, David , 2018. Decreasing fire season precipitation increased recent western US forest wildfire activity
    Parks, Sean A.; Holsinger, Lisa M.; Panunto, Matthew H.; Jolly, William M.; Dobrowski, Solomon Z.; Dillon, Gregory K. , 2018. High-severity fire: Evaluating its key drivers and mapping its probability across western US forests
    Parsons, Russell A.; Pimont, Francois; Wells, Lucas; Cohn, Gregory M.; Jolly, William M.; de Coligny, Francois; Rigolot, Eric; Dupuy, Jean-Luc; Mell, William; Linn, Rodman R. , 2018. Modeling thinning effects on fire behavior with STANDFIRE
    Daham, Afrah; Han, Dawei; Jolly, William M.; Rico-Ramirez, Miguel; Marsh, Anke , 2018. Predicting vegetation phenology in response to climate change using bioclimatic indices in Iraq
    Jolly, William M.; Johnson, Daniel M. , 2018. Pyro-ecophysiology: Shifting the paradigm of live wildland fuel research
    Mason, Shelby A.; Hamlington, Peter E.; Hamlington, Benjamin D.; Jolly, William M.; Hoffman, Chad M. , 2017. Effects of climate oscillations on wildland fire potential in the continental United States
    Goodrick, Scott L.; Brown, Timothy J.; Jolly, William M. , 2017. Weather, fuels, fire behavior, plumes, and smoke - the nexus of fire meteorology
    Williamson, Grant J.; Prior, Lynda D.; Jolly, William M.; Cochrane, Mark A.; Murphy, Brett P.; Bowman, David M. J. S. , 2016. Measurement of inter- and intra-annual variability of landscape fire activity at a continental scale: The Australian case
    Preisler, Haiganoush K.; Riley, Karin; Stonesifer, Crystal S.; Calkin, Dave E.; Jolly, William M. , 2016. Near-term probabilistic forecast of significant wildfire events for the Western United States
    Jolly, William M.; Hintz, John; Linn, Rodman L.; Kropp, Rachael C.; Conrad, Elliot T.; Parsons, Russell A.; Winterkamp, Judith , 2016. Seasonal variations in red pine (Pinus resinosa) and jack pine (Pinus banksiana) foliar physio-chemistry and their potential influence on stand-scale wildland fire behavior
    Werth, Paul A.; Potter, Brian E.; Alexander, Martin E.; Clements, Craig B.; Cruz, Miguel G.; Finney, Mark A.; Forthofer, Jason M.; Goodrick, Scott L.; Hoffman, Chad; Jolly, William M.; McAllister, Sara S.; Ottmar, Roger D.; Parsons, Russell A. , 2016. Synthesis of knowledge of extreme fire behavior: volume 2 for fire behavior specialists, researchers, and meteorologists
    Peterson, Birgit; Nelson, Kurtis J.; Seielstad, Carl; Stoker, Jason; Jolly, William M.; Parsons, Russell A. , 2015. Automated integration of lidar into the LANDFIRE product suite
    Keane II, Robert E.; Jolly, William M.; Parsons, Russell A.; Riley, Karin , 2015. Proceedings of the large wildland fires conference; May 19-23, 2014; Missoula, MT
    Parsons, Russell A.; Jolly, William M.; Langowski, Paul; Matonis, Megan; Miller, Sue , 2014. Post-epidemic fire risk and behavior [Chapter 3]
    Qi, Yi; Dennison, Philip E.; Jolly, William M.; Kropp, Rachael C.; Brewer, Simon C. , 2014. Spectroscopic analysis of seasonal changes in live fuel moisture content and leaf dry mass
    Jolly, William M.; Parsons, Russell A.; Varner, J. Morgan; Butler, Bret W.; Ryan, Kevin C.; Gucker, Corey L. , 2012. Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?
    Finney, Mark A.; ; McAllister, Sara S.; Jolly, William M. , 2012. On the need for a theory of wildland fire spread
    McAllister, Sara S.; Grenfell, Isaac C.; Hadlow, A.; Jolly, William M.; Finney, Mark A.;  , 2012. Piloted ignition of live forest fuels
    Cooke, William H.; Mostovoy, Georgy V.; Anantharaj, Valentine G.; Jolly, William M. , 2012. Wildfire potential mapping over the state of Mississippi: A land surface modeling approach
    Grenfell, Isaac C.; Finney, Mark A.; Jolly, William M. , 2010. Simulating spatial and temporally related fire weather
    CONUS-wide 4-km maps illustrating the process of mapping the Severe Fire Danger Index (SFDI) for a single day on 10 Jun 2006.
    Fire scientists at Rocky Mountain Research Station developed the Severe Fire Danger Index (SFDI). SFDI is a spatial fire danger index that can be used to assess historical events, forecast extreme fire danger, and communicate those conditions to both firefighters and the public. Severe fire hazard conditions occur about 3% of the time in any given place and are correlated with the gravest outcomes.  
    A map of the Soberanes Fire with color coded points indicating the night on which nighttime fire hotspots occurred.
    Understanding the potential for a wildfire to continue burning through the night has important implications for firefighter and community preparedness. This work has found that as wildfire sizes have increased since 2003, satellite sensors have detected increases in nighttime wildfire fire activity. 
    Icon of a laptop and a smart phone together, both displaying the same image of a screenshot from the Wildfire SAFE application. The screenshot contains a map with a red tinted area in the middle.
    When responding to a wildfire, fire managers need to consider a lot of information, like terrain in the area, vegetation conditions, and weather forecasts. When this information is spread across multiple data sources and web platforms, it can be more difficult to understand fire hazards and prioritize resources on the fly. The new app WildfireSAFE integrates real-time data from multiple data sources, like drought conditions from the U.S. Drought Monitor and satellite-derived vegetation conditions, into a single, user-friendly web platform.
    A map of the United States showing firefighter entrapments with circles, where the size of the circle indicates number of personnel entrapped and the color of the circle indicates whether or not fatalities occurred.
    A literature and data review were conducted to advance our understanding of the causes of firefighter entrapments. We identified several research needs related to a lack of knowledge, inadequate tools, and improved methods for data collection and storage. Prioritizing these needs will be difficult since they all have the potential improve firefighter safety, either directly or indirectly.
    Fire Danger Rating System
    The National Fire Danger Rating System (NFDRS) is a system that allows fire managers to estimate today's or tomorrow's fire danger for a given area. In 2014, RMRS fire danger rating system developers sought and gained approval to update the U.S. National Fire Danger Rating System (NFDRS).
    Photo of a forest fire
    The number and size of large wildfires have increased dramatically in the western United States during the past three decades. Prior understanding was that the increase in fires was mainly attributable to warming temperatures and earlier snowmelt. In this study, a research team contrasted the three main hypothesized climatic drivers of recent increases in western US wildfire activity: decreased snowpack, increased temperature, and decreased precipitation.
    2007 Castle Rock Fire in Ketchum, ID (c) Kari Greer/NIFC
    The length of the fire weather season is one of many factors that must be understood to ensure that wildfires are effectively managed to promote healthy ecosystems while minimizing negative socio-economic impacts. While fire weather seasons aren't getting consistently longer everywhere, unusually long fire weather seasons are becoming more frequent across many fire-prone regions, like parts of Australia, Alaska, and the Eurasian boreal forests where significant long-term trends are absent.
    Red mountain pine beetles are dry and highly flammable.
    Beetle-killed trees lose their needles over time, and once all the needles have dropped, crown fire danger largely disappears. However, red-needled trees have lower foliar moisture contents than healthy trees, which leads to increased crown fire potential. This research provides insights into the potential use of fuel treatments in beetle-killed forests, increases firefighter awareness of dangerous situations, and assists managers in identifying areas at high risk for ignition and extreme fire behavior.
    FPARDY (Fuel PARticle DYnamics), is one of many new efforts to explore surface fuel characteristics at the particle, layer, and fuelbed levels across major forest ecosystem types in the US northern Rocky Mountains (NRM) to develop a set of products that integrate these findings into standard fuel applications.
    The ecological, economic and health and safety concerns surrounding wildland fires are driving the need to better understand climate-fire interactions.
    The ecological, economic, and health and safety concerns surrounding wildland fires are driving the need to better understand climate-fire interactions.
    Wildfires occur at the intersection of dry weather, available fuel, and ignition sources. Weather is the most variable and largest driver of regional burned area. Temperature, relative humidity, precipitation, and wind speed independently influence wildland fire spread rates and intensities. The alignment of multiple weather extremes, such as the co-occurrence of hot, dry, and windy conditions, leads to the most severe fires.
    Rocky Mountain Research Station scientists and their partners are conducting a project to explore what makes fuel treatments effective. The project, STANDFIRE, is a platform through which new fire science can be tested, assessed, and incorporated into fuel treatment analysis.
    Considerable effort is expended to determine fuel loading and to map those loadings across the landscape, yet there is little or no work being done to determine how to incorporate those measurements into the next generation of fire behavior models, such as physics-based models. Identifying critical spatial and temporal fuel characteristics required by these models may help to refine field sampling procedures and ensure a tight coupling between how fuels are measured and how those measurements are then used to assess potential fire behavior.
    For decades, the cause and timing of a 'spring dip' in foliar moisture content in red and jack pine in the Great Lakes region have been poorly understood. This project studies the drivers of this 'dip' in order to improve wildland firefighter preparedness.
    Fire spread in live fuels has long presented conundrums for managers and defied explanation by researchers. Fire, Fuel and Smoke researchers with collaborators from the Fire and Fuels Program at the Pacific Southwest Research Station, Brigham Young University, and the University of Alabama-Huntsville performed a two-year study of the seasonal changes in the ignition behavior of ten shrub and tree species from southern California, Utah, western Montana, and Florida.
    Current operational fire behavior models are empirically based on fire spread through surface fuels and do not describe heating and combustion processes. RMRS Fire, Fuel, and Smoke Science Program scientists and collaborators have developed a research program for understanding how fire spread occurs with a focus on live fuels and active crown fire.