Dr. Keeley is currently a research scientist with the U.S. Geological Survey, stationed at Sequoia National Park.
Prior to this appointment, he served one year in Washington, D.C. as director of the ecology program for the National Science Foundation. He was professor of biology at Occidental College for 20 years and spent a sabbatical year at the University of Cape Town, South Africa. He has more than 350 publications in national and international scientific journals and books. His research has focused on ecological impacts of wildfires as well as other aspects of plant ecology, including rare plants, rare habitats such as vernal pools, and plant physiology. In 1985 he was awarded a Guggenheim Fellowship and is a Fellow of the Ecological Society of America and an Honorary Lifetime Member of the California Botanical Society. He has served on the Los Angeles County Department of Regional Planning Environmental Review Board, and the State of California Natural Communities Conservation Program (NCCP) Board of Scientific Advisors.
U.S. Geological Survey, Western Ecological Research Center, Research Scientist
(ST Scientist), 2015–present
(GS series 0408), 1998–present
University of California, Los Angeles, Adjunct Full Professor, 2001-present
Rancho Santa Ana Botanic Garden, Research Associate, 1997–present
National Science Foundation, Program Director 1997–1998
Department Chair 1982–1988
Assist/Assoc Professor 1977–1988
University of Cape Town, Visiting Professor 1990
Education and Certifications
Ph.D. (Botany) University of Georgia, Athens, 1977
M.S. (Biology) San Diego State University, 1973
B.S. (Biology) San Diego State University, 1971
Honors and Awards
Fellow, Ecological Society of America, 2014
Distinguished MEDECOS Fellow, 2011
USGS Performance Award, 2011
USGS Star Award, 2008
Honorary Lifetime Member, California Botanical Society, 1998
Fellow, Southern California Academy of Sciences, l994
Guggenheim Fellow, l985–l986
Sterling Award for Outstanding Teaching, l985
Science and Products
WERC Fire Science
Understanding Fire-caused Vegetation Type Conversion in Southwestern Conifer Forests under Current and Future Climate Conditions
Preventing Extreme Fire Events by Learning from History: The Effects of Wind, Temperature, and Drought Extremes on Fire Activity
Southern California Wildfire Risk Scenario Project
Invasive Plants and Fire
Environmental Change and Fire
Balancing Fire Hazards and Resource Protection
Sequoia and Kings Canyon Field Station
Field Studies of Ceanothus leucodermis Chaparral Burned Sites in California
Vegetation Type Conversion in Southern California Between 1943 and 2018
The Effect of Prolonged Drought on Chaparral Dieback within the Perimeters of the Thomas and Woolsey Fires in Southern California, USA
Data for Use in poscrptR Post-fire Conifer Regeneration Prediction Model
Survey Data for Chaparral Vegetation in Masticated Fuel Treatments on the four Southern California National Forests (2011-2012)
Vegetation type conversion in chaparral in San Diego County, California, USA between 1953 and 2016
Demographic data for Hesperocyparis forbesii on Otay Mountain 2004-2017
Chaparral Type Conversion into Herbaceous Vegetation in Coastal Southern California from 1947 to 2014, Data Compiled from Aerial Imagery, Geographic NAD83 (2017)
Arctostaphylos Occurence and Historical Fires table
Evolutionary ecology of fire
Autumn precipitation: The competition with Santa Ana winds in determining fire outcomes in southern California
What makes wildfires destructive in California?
The effects of prolonged drought on vegetation dieback and megafires in southern California chaparral
Bet-hedging and best-bet strategies shape seed dormancy
Vegetation type conversion in the US Southwest: Frontline observations and management responses
Mechanisms of forest resilience
Climate change and plant regeneration from seeds in Mediterranean regions of the Northern Hemisphere
Large California wildfires: 2020 fires in historical context
Ignitions explain more than climate or weather in driving Santa Ana Wind fires
Wildfires and global change
Seed source, not drought, determines patterns of seed production in Sierra Nevada conifers
Science and Products
WERC Fire ScienceWERC scientists are defining the past, present, and future of wildfires for wildlife and human communities. Explore this webpage to learn about specific, ongoing projects across California and parts of Nevada.
Understanding Fire-caused Vegetation Type Conversion in Southwestern Conifer Forests under Current and Future Climate ConditionsFire size, frequency, overall area burned, and severity are increasing across many vegetation types in the southwestern U.S. In many cases, large contiguous areas are burning repeatedly at high severity, triggering vegetation type conversions (VTC), where once-dominant coniferous forests fail to return to their pre-fire state, often transitioning to shrub- or grass-dominated systems. Loss of these
Preventing Extreme Fire Events by Learning from History: The Effects of Wind, Temperature, and Drought Extremes on Fire ActivityThe 2017 fire season in California was highly unusual with its late seasonal timing, the areal extent it burned, and its devastation to communities. These fires were associated with extreme winds and were potentially also influenced by unusually dry conditions during several years leading up to the 2017 events. This fire season brought additional attention and emphasized the vital need for manager
Southern California Wildfire Risk Scenario ProjectEvery year, wildfires devastate the landscapes of Southern California from Los Angeles to San Diego. How has a higher number of human-caused fires affected fire hazards and threats to resources? WERC’s Dr. Jon Keeley and collaborators are analyzing fire patterns across the state to help cities balance their management of fire hazards and natural resources.
Invasive Plants and FireFire has had a very different influence on the forests and shrublands of California. Unlike the case in many forests where fires have been excluded for over a century, shrublands throughout the state have experienced the opposite impact. Invasive grasses that burn more readily than native plants have increased the frequency of wildfires in southern California shrublands. As fire clears swathes of...
Environmental Change and FireThe effects of a changing environment can ripple throughout an ecosystem. Increased temperatures and more frequent and severe droughts in the future may influence wildfire patterns as well as water resources for communities. Dr. Jon Keeley and partners are using nearly a century’s worth of fire data to aid local landowners, and state and Federal agencies in planning for wildfire on evolving...
Balancing Fire Hazards and Resource ProtectionHuman impacts on fires across California have been quite diverse. In many forests, fires have been nearly excluded over the past century, causing an unhealthy accumulation of dead vegetation and a greater threat of severe fires. However, on much of California’s lower elevation foothills and valleys, humans have greatly increased fire frequency. These landscapes are often juxtaposed with...
Sequoia and Kings Canyon Field StationThe Sequoia and Kings Canyon Field Station is home to research programs that focus on wildfire patterns in Southern California, and the effects of drought on Sierra Nevada forests. Select the "Science" tab for a more comprehensive summary.
Field Studies of Ceanothus leucodermis Chaparral Burned Sites in CaliforniaPopulations of the chaparral shrub were sampled in southern California and further north in Monterey and Santa Clara counties and it was discovered that postfire regeneration modes were different. The southern California populations had substantial resprouting with some seedling recruitment. The Monterey populations had no resprouting ability and recovery was entirely by seedlings. However, there
Vegetation Type Conversion in Southern California Between 1943 and 2018This dataset contains data pertaining to ground surface cover in 30 meter plots around a random selection of points within chaparral from Santa Barbara county south to San Diego County in southern California, USA. These data were obtained from historical aerial imagery from 1943 to 1959 and current imagery from 2016 to 2018 and they were compared to quantify changes in cover type over time. These
The Effect of Prolonged Drought on Chaparral Dieback within the Perimeters of the Thomas and Woolsey Fires in Southern California, USAThis dataset contains data pertaining to chaparral vegetation dieback based on the difference or change in the Normalized Difference Vegetation Index (NDVI) prior to and 6 years into an extensive drought before the 2017 Thomas and 2018 Woolsey Fires in southern California. The difference in mean NDVI is provided for 9322 study plots as are values for a number of physical and climatological variabl
Data for Use in poscrptR Post-fire Conifer Regeneration Prediction ModelThese data support poscrptR (Wright et al. 2021). poscrptR is a shiny app that predicts the probability of post-fire conifer regeneration for fire data supplied by the user. The predictive model was fit using presence/absence data collected in 4.4m radius plots (60 square meters). Please refer to Stewart et al. (2020) for more details concerning field data collection, the model fitting process, an
Survey Data for Chaparral Vegetation in Masticated Fuel Treatments on the four Southern California National Forests (2011-2012)Mechanical fuel treatments are a primary pre-fire strategy for potentially mitigating the threat of wildland fire, yet there is limited information on how they impact shrubland ecosystems. This publication contains data related to vegetation structure and composition in mechanically masticated chaparral communities used to assess the impact of these fuel treatments on shrubland vegetation and to d
Vegetation type conversion in chaparral in San Diego County, California, USA between 1953 and 2016This dataset contains data pertaining to ground surface cover in a 30 meter radius around a random selection of points within San Diego County, California. These data were obtained from aerial imagery for the years 1953 and 2016 and were used to assess changes in cover type over time. These data support the following publication: Syphard, A.D., Brennan, T.J. and Keeley, J.E., 2019. Extent a
Demographic data for Hesperocyparis forbesii on Otay Mountain 2004-2017This dataset contains demographic data pertaining to Hesperocyparis forbesii on Otay Mountain in San Diego County, California, USA, over a 14-year study period from 2004 to 2017 following the 2003 Otay/Mine Fire. Site variables including elevation, incline, and slope were collected as well as pre-fire tree density and stand age for 16 study site locations. Tree density, height, and cone production
Chaparral Type Conversion into Herbaceous Vegetation in Coastal Southern California from 1947 to 2014, Data Compiled from Aerial Imagery, Geographic NAD83 (2017)This dataset contains data pertaining to vegetation type, woody versus herbaceous versus non-vegetated, for a random selection of points within the Santa Monica Mountains National Recreation Area of Southern California. These data were obtained from aerial imagery for the years 1947, 1977, 1995, 2005, and 2014 and were used to determine changes in cover type over time. These data support the
Arctostaphylos Occurence and Historical Fires tableEcological factors favoring either resprouting or obligate seeding in plants have received considerable attention recently. Three ecological models have been proposed to explain patterns of these two life history types. In this study we test these three models using data from California chaparral. We take an innovative approach to testing these models by not testing community or landscape patterns
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Evolutionary ecology of fireFire has been an ecosystem process since plants colonized land over 400 million years ago. Many diverse traits provide a fitness benefit following fires, and these adaptive traits vary with the fire regime. Some of these traits enhance fire survival, while others promote recruitment in the postfire environment. Demonstrating that these traits are fire adaptations is challenging, since many arose e
Autumn precipitation: The competition with Santa Ana winds in determining fire outcomes in southern CaliforniaBackground: California’s South Coast has experienced peak burned area in autumn. Following typically dry, warm summers, precipitation events and Santa Ana winds (SAWs) each occur with increasing frequency from autumn to winter and may affect fire outcomes.Aims: We investigate historical records to understand how these counteracting influences have affected fires.Methods: We defined autumn precipit
What makes wildfires destructive in California?As human impacts from wildfires mount, there is a pressing need to understand why structures are lost in destructive fires. Despite growing research on factors contributing to structure loss, fewer studies have focused on why some fires are destructive and others are not. We characterized overall differences between fires that resulted in structure loss (“destructive fires”) and those that did not
The effects of prolonged drought on vegetation dieback and megafires in southern California chaparralDrought contributed to extensive dieback of southern California chaparral, and normalized difference vegetation index before drought and near the end of the drought was used to estimate this dieback, after accounting for other disturbances recorded in aerial photographs. Within the perimeters of two megafires that occurred after the drought, the 2017 Thomas Fire and the 2018 Woolsey Fire, there ha
Bet-hedging and best-bet strategies shape seed dormancySeed dormancy (i.e. delayed germination even when conditions are favourable) is a key plant characteristic that occurs among many species worldwide. But, what selective pressures led to seed dormancy? A recent study provides a major analysis of the factors driving this trait at the global scale (Zhang et al., 2022). Using c. 12 000 species and 10 million records across the globe, they conclude tha
Vegetation type conversion in the US Southwest: Frontline observations and management responsesForest and nonforest ecosystems of the western United States are experiencing major transformations in response to land-use change, climate warming, and their interactive effects with wildland fire. Some ecosystems are transitioning to persistent alternative types, hereafter called “vegetation type conversion” (VTC). VTC is one of the most pressing management issues in the southwestern US, yet cur
Mechanisms of forest resilienceEcosystems are dynamic systems with complex responses to environmental variation. In response to pervasive stressors of changing climate and disturbance regimes, many ecosystems are realigning rapidly across spatial scales, in many cases moving outside of their observed historical range of variation into alternative ecological states. In some cases, these new states are transitory and represent su
Climate change and plant regeneration from seeds in Mediterranean regions of the Northern HemisphereMediterranean regions are biodiversity hotspots whose landscapes are characterized by evergreen sclerophyllous vegetation, mild-wet winters, and hot-dry summers. In the Northern Hemisphere, they occur in the Mediterranean Basin and California regions. In these areas, whose habitats are heavily shaped by centuries of anthropic activities, the main effects of climate change include a decrease in pre
Large California wildfires: 2020 fires in historical contextBackgroundCalifornia in the year 2020 experienced a record breaking number of large fires. Here, we place this and other recent years in a historical context by examining records of large fire events in the state back to 1860. Since drought is commonly associated with large fire events, we investigated the relationship of large fire events to droughts over this 160 years period.ResultsThis study s
Ignitions explain more than climate or weather in driving Santa Ana Wind firesAutumn and winter Santa Ana wind (SAW)–driven wildfires play a substantial role in area burned and societal losses in southern California. Temperature during the event and antecedent precipitation in the week or month prior play a minor role in determining area burned. Burning is dependent on wind intensity and number of human-ignited fires. Over 75% of all SAW events generate no fires; rather, fi
Wildfires and global changeNo single factor produces wildfires; rather, they occur when fire thresholds (ignitions, fuels, and drought) are crossed. Anomalous weather events may lower these thresholds and thereby enhance the likelihood and spread of wildfires. Climate change increases the frequency with which some of these thresholds are crossed, extending the duration of the fire season and increasing the frequency of dry
poscrptRposcrptR is a simple R package with the sole purpose of distributing a shiny app for predicting post-fire conifer regeneration. Learn more about shiny apps here.
Seed source, not drought, determines patterns of seed production in Sierra Nevada conifersThis release consists of data collected from 26 plots in two national parks over a 19-year period. The data consists of plot-level seed counts for three genera, number of seed traps, live tree basal area, plot area, and climate metrics from the gridmet gridded data set, the daymet gridded data set, the PRISM gridded data set, and two nearby COOP stations.