I am an Ecologist with the U.S. Geological Survey's Western Ecological Research Center, stationed at Sequoia and Kings Canyon National Parks. I study tree dynamics with a particular focus on tree mortality processes. My work is aimed at improving our understanding of western forests and increasing our capacity to assess how they will be affected by a changing climate.
RESEARCH INTERESTS
- Forest ecology
- Forest dynamics
- Tree mortality
- Tree growth
- Climatic change
Education and Certifications
PhD from University of California at Berkeley, Forest Ecology 2007
BS from University of Michigan, Chemistry and Cellular Molecular Biology, 1995
Science and Products
Forest health and drought response
Forests provide society with economically important and often irreplaceable goods and services, such as wood products, carbon sequestration, clean water, biodiversity, and recreational opportunities. Yet hotter droughts (droughts in which unusually high temperatures exacerbate the effects of low precipitation) are projected to increase in frequency and intensity in coming decades, potentially...
Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?
The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. C
Sequoia and Kings Canyon Field Station
The 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.
Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts
Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...
Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest
Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this imm
Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?
In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...
Characterizing a link in the terrestrial carbon cycle: a global overview of individual tree mass growth
Forests sequester the majority of the terrestrial biosphere’s carbon and are key components of the global carbon cycle, potentially contributing substantial feedbacks to ongoing climatic changes. It is therefore remarkable that no consensus yet exists about the fundamental nature of tree mass growth (and thus carbon sequestration rate). Specifically, does tree mass growth rate increase, decrease,
Assessment of Giant Sequoia Mortality and Regeneration within Burned Groves in Sequoia and Kings Canyon National Parks
Provided are data containing condition assessments on individual giant sequoia (Sequoiadendron giganteum; SEGI) stems and post-fire regeneration counts within Board Camp, Suwanee, New Oriole Lake, and a subset of Redwood Mountain groves of Sequoia and Kings Canyon national parks, respectively. Stem data contain condition-related attributes (e.g., spatial location, diameter breast height, status -
Calibration and Validation Data and Model Coefficients for Mixed Conifer Vulnerability Project from Sequoia and Kings Canyon National Park 2015 to 2019
These datasets contain the attributes of individual trees located in and around Sequoia and Kings Canyon national parks. Attributes include remote sensing indices, terrain characteristics, and-- for the calibration data-- tree size and growth rates. Calibration data (mixedconifervulnerability_calibrationdataset.csv) were collected in long term research plots where trees are visited annually to che
Sequoia and Yosemite National Parks Mortality and Fire Data (1990-2019) for Competition-Fire-Drought Interaction Analysis
This dataset records mortality-- including involvement of bark beetles-- and burn severity information for trees in long term forest dynamics plots in Sequoia National Park and Yosemite National Park that experienced fire.
These data support the following publication:
Furniss, T.J., Das, A.J., van Mantgem, P.J., Stephenson, N.L. and Lutz, J.A., 2021. Crowding, climate, and the case for soci
Data for Use in poscrptR Post-fire Conifer Regeneration Prediction Model
These 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
Forest Structure Data for Burned and Unburned Sites at Sequoia and Kings Canyon National Parks
These data represent tree diameter, species, mortality status, and plot attributes from 164 plots in Sequoia and Kings Canyon national parks, California. Plots were matched with local records of recent fire history to determine burn status and year burned if applicable.
These data support the following publication:
van Mantgem, P.J., Caprio, A.C., Stephenson, N.L. and Das, A.J., 2021. Forest Re
Post-fire conifer regeneration observations for National Forest land in California (2009 - 2017)
This data consists of presence/absence observations for post-fire conifer regeneration. The data also includes estimates of plot-level topography (slope, aspect), relativized differenced normalized burn ratio (RdNBR), post-fire climate, live basal area, and seed rain.
These data support the following publication:
Seed and Associated Tree Data from Long Term Research Plots in Sequoia and Yosemite national parks
This dataset was used as part of a continent-wide analysis of tree fecundity and its association with climate and tree size. This dataset consists of: plotinfo.csv, which contains basic attribute information for the field plots where the data were collected; seeddata.csv, which contains the data for seeds collected (how many, what type, etc.); trapxycoord.csv, which contains location and identific
Tree mortality in blue oak woodlands in Sequoia National Park during the extreme drought
These data were collected to quantify oak mortality during the 2014-2017 drought. 30 tenth hectare drought plots were established throughout the blue oak woodland of Sequoia National Park. Information on species, size, and mortality were collected for all standing trees in each plot. In addition, two long-term 2.25 ha plots were established, in which the same data were collected.
Seedling and tree data from Sequoia National Park and Yosemite National Park
These tables include data from 25 long-term forest plots located in either Sequoia or Yosemite national park. Trees in these plots (established between 1982 and 2001) are censused annually for mortality and measured for diameter every 4 to 6 years. Plots were mostly 1 hectare (ha) in size (range 0.9 - 2.5 ha) and contained at least two 25 by 25 meter seedling sub-plots to monitor natural seedling
Tree mortality in Sequoia National Park from 2004 to 2007 and during severe drought in 2014 to 2017
These data describe tree mortality and the factors associated with tree mortality for a variety of plots in Sequoia National Park. Most of the data were collected between 2014 and 2017 (during an extremely severe drought), along with some comparison data from 2004 to 2007.
These data support the following publication:
Stephenson, N.L., Das, A.J., Ampersee, N.J., Bulaon, B.M., and Yee, J.L.,
Sequoia foliage dieback data from Sequoia National Park
These datasets provide spatially-explicit estimates of the magnitude of giant sequoia foliage dieback along selected trail corridors in Sequoia and Kings Canyon national parks, California, from 2014 through 2017. They additionally provide giant sequoia tree-ring measurements, through the year 1989, for two locations in the Giant Forest grove, Sequoia National Park, California.
Mortality factors for dead trees from a subset of plots from the Sierra Nevada Forest Dynamics Plot Network from 1998 to 2010
This dataset was used to summarize and analyze the mortality factors recorded on dead trees in the Sierra Nevada Forest Dynamics Plot Network, which is managed by the Sequoia and Kings Canyon Field station of the U.S. Geological Survey's Western Ecological Research Center. Each row of the dataset represents an individual dead tree. These are dead trees that were recorded in the network from 1998 t
Filter Total Items: 48
Linking seed size and number to trait syndromes in trees
AimOur understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whether reproduction represents an independent dimension
Authors
Michal Bogdziewicz, Marie-Claire Aravena Acuña, Robert A. Andrus, Davide Ascoli, Yves Bergeron, Daniel Brveiller, Thomas Boivin, Raul Bonal, Thomas Caignard, Maxime Cailleret, Rafael Calama, Sergio Donoso Calderon, J. Julio Camarero, Chia-Hao Chang-Yang, Jerome Chave, Francesco Chianucci, Natalie L. Cleavitt, Benoit Courbaud, Andrea Cutini, Thomas Curt, Adrian Das, Hendrik Davi, Nicolas Delpiere, Sylvain Delzon, Michael Dietze, Laurent Dormont, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzer, Cathryn H. Greenberg, Arthur Guignabert, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Valentin Journé, Thomas Kitzberger, Johannes M.H. Knops, Georges Kunstler, Richard Kobe, Jonathan G. A. Lageard, Jalene M. LaMontagne, Mateusz Ledwon, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Anders Marell, Eliot J.B. McIntire, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Shoji Naoe, Kyotaro Noguchi, Michio Oguro, Hiroko Kurokawa, Jean-Marc Ourcival, Robert Parmenter, Ignacio M. Perez-Ramos, Lukasz Piechnik, Tomasz Podgórski, John Poulsen, Tong Qiu, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, Pavel Šamonil, Jan Holik, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Mitsue Shibata, Shubhi Sharma, Miles Silman, Michael A. Steele, Jacob N. Straub, I-Fang Sun, Samantha Sutton, Jennifer J. Swenson, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Boyd Wright, S. Joseph Wright, Thomas G. Whitham, Kai Zhu, Jess K. Zimmerman, Magdalna Zywiec, James S. Clark
Climate change risks to global forest health: Emergence of unexpected events of elevated tree mortality worldwide
Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about climate change risks to global forest health. We currently lack both sufficient data and understanding to identify whether these observations represent a global trend towards increasing tree mortality. Here, we document events of sudden and unexpected elevated tree mortality follo
Authors
Henrik Hartmann, Ana Bastos, Adrian Das, Adriane Esquivel-Muelbert, William M Hammond, Jordi Martínez-Vilalta, Nate G. McDowell, Jennifer S. Powers, Thomas A. M. Pugh, Katinka X. Ruthrof, Craig D. Allen
Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery
The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four ma
Authors
Tong Qiu, Robert Andrus, Marie-Claire Aravena Acuna, Davide Ascoli, Yves Bergeron, Roberta Berretti, Daniel Berveiller, Thomas Biovin, Raul Bonal, Don C. Bragg, Thomas Caignard, Rafael Calama, J. Julio Camarero, Chia-Huo Chang-Yang, Natalie L. Cleavitt, Benoit Courbaud, Francois Courbet, Thomas Curt, Adrian Das, Evangelia Daskalakou, Hendrik Davi, Nicolas Delpierre, Sylvain Delzon, Michael Dietze, Sergio Donoso Calderon, Laurent Dormont, Josep Maria Espelta, Timothy J. Fahey, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzner, Cathryn H. Greenberg, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Valentin Journé, Daisuke Kabeya, Christopher L. Kilner, Thomas Kitzberger, Johannes M. H. Knops, Richard K. Kobe, Georges Kunstler, Hiroko Kurokawa, Jonathan G. A. Lageard, Jalene LaMontagne, Mateusz Ledwon, Francois Lefevre, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Christopher M. Moore, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Kyotaro Noguchi, Jean-Marc Ourcival, Robert Parmenter, Ian Pearse, Ignacio M. Perez-Ramos, Lukasz Piechnik, John Poulsen, Renata Poulton-Kamakura, Miranda Redmond, Chantal D. Reid, Kyle C. Rodman, Francisco Rodrigues-Sanchez, Javier Sanguinetti, C. Lane Scher, Wiliam H Schlesinger, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Michael A. Steele, Nathan L. Stephenson, Jacob N. Straub, I-Fang Sun, Samantha Sutton, Jennifer J. Swenson, Margaret Swift, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas Wion, Boyd Wright, S. Joseph Wright, Kai Zhu, Jess Zimmermann, Roman Zlotin, Magdalena Zywiec, James S. Clark
Globally, tree fecundity exceeds productivity gradients
Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250-fold increase in seed abundance from cold-dry to warm-wet climates, driven primarily by a 100-fold increase in seed production for a give
Authors
Valentin Journé, Robert A. Andrus, Marie-Claire Aravena Acuna, Davide Ascoli, Roberta Berretti, Daniel Berveiller, Michal Bogdziewicz, Thomas Boivin, Raul Bonal, Thomas Caignard, Rafael Calama, J. Julio Camarero, Chia-Hao Chang-Yang, Benoit Courbaud, Francois Courbet, Thomas Curt, Adrian Das, Evangelia Daskalakou, Hendrik Davi, Nicolas Delpierre, Sylvain Delzon, Michael Dietze, Sergio Donoso Calderon, Laurent Dormont, Josep Maria Espelta, Timothy J. Fahey, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzer, Cathryn H. Greenberg, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Daisuke Kabeya, Roland Kays, Thomas Kitzberger, Johannes M. H. Knops, Richard K. Kobe, Georges Kunstler, Jonathan G. A. Lageard, Jalene M. LaMontagne, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Christopher M. Moore, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Kyotaro Noguchi, Jean-Marc Ourcival, Robert Parmenter, Ian Pearse, Ignacio M. Perez-Ramos, Lukasz Piechnik, John Poulsen, Renata Poulton-Kamakura, Tong Qiu, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, Francisco Rodriguez-Sanchez, Javier D Sanguinetti, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Michael A. Steele, Nathan L. Stephenson, Jacob N. Straub, Jennifer J. Swenson, Margaret Swift, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Boyd Wright, S. Joseph Wright, Kai Zhu, Jess K. Zimmerman, Roman Zlotin, Magdalena Zywiec, James S. Clark
North American tree migration paced by climate in the West, lagging in the East
Tree fecundity and recruitment have not yet been quantified at scales needed to anticipate biogeographic shifts in response to climate change. By separating their responses, this study shows coherence across species and communities, offering the strongest support to date that migration is in progress with regional limitations on rates. The southeastern continent emerges as a fecundity hotspot, but
Authors
Shubhi Sharma, Robert Andrus, Yves Bergeron, Michal Bogdziewicz, Don C. Bragg, Dale G. Brockway, Natalie L. Cleavitt, Benoit Courbaud, Adrian Das, Michael Dietze, Timothy J. Fahey, Jerry F. Franklin, Gilbert S. Gregory, Cathryn H. Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Ines Ibanez, Jill F. Johnstone, Christopher L. Kilner, Johannes M. H. Knops, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Diana Macias, Emily V. Moran, Jonathan A. Myers, Robert Parmenter, Ian Pearse, Renata Poulton-Kamakura, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, William H. Schlesinger, Michael A. Steele, Nathan L. Stephenson, Jennifer J. Swenson, Margaret Swift, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, Christopher W. Woodall, Roman Zlotin, James S. Clark
Empirically validated drought vulnerability mapping in the mixed conifer forests of the Sierra Nevada
Severe droughts are predicted to become more frequent in the future, and the consequences of such droughts on forests can be dramatic, resulting in massive tree mortality, rapid change in forest structure and composition, and substantially increased risk of catastrophic fire. Forest managers have tools at their disposal to try to mitigate these effects but are often faced with limited resources, f
Authors
Adrian Das, Michèle R Slaton, Jeffrey Mallory, Gregory P. Asner, Roberta E. Martin, Paul Hardwick
Crowding, climate, and the case for social distancing among trees
In an emerging era of megadisturbance, bolstering forest resilience to wildfire, insects, and drought has become a central objective in many western forests. Climate has received considerable attention as a driver of these disturbances, but few studies have examined the complexities of climate–vegetation–disturbance interactions. Current strategies for creating resilient forests often rely on retr
Authors
Tucker J. Furniss, Adrian Das, Phillip J. van Mantgem, Nathan L. Stephenson, James A. Lutz
Forest resistance to extended drought enhanced by prescribed fire in low elevation forests of the Sierra Nevada
Prescribed fire reduces fire hazards by removing dead and live fuels (small trees and shrubs). Reductions in forest density following prescribed fire treatments (often in concert with mechanical treatments) may also lessen competition so that residual trees might be more likely to survive when confronted with additional stressors, such as drought. The current evidence for these effects is mixed an
Authors
Phillip J. van Mantgem, Anthony C. Caprio, Nathan L. Stephenson, Adrian Das
Nonlinear shifts in infectious rust disease due to climate change
Range shifts of infectious plant disease are expected under climate change. As plant diseases move, emergent abiotic-biotic interactions are predicted to modify their distributions, leading to unexpected changes in disease risk. Evidence of these complex range shifts due to climate change, however, remains largely speculative. Here, we combine a long-term study of the infectious tree disease, whit
Authors
Joan Dudney, Claire Willing, Adrian Das, Andrew M. Latimer, Jonathan C B Nesmith, John J. Battles
Mapping the vulnerability of giant sequoias after extreme drought in California using remote sensing
Between 2012 and 2016, California suffered one of the most severe droughts on record. During this period Sequoiadendron giganteum (giant sequoias) in the Sequoia and Kings Canyon National Parks (SEKI), California, USA experienced canopy water content (CWC) loss, unprecedented foliage senescence, and, in a few cases, death. We present an assessment of the vulnerability of giant sequoia populations
Authors
Andres Baeza, Roberta E. Martin, Nathan L. Stephenson, Adrian Das, Paul Hardwick, Koren R. Nydick, Jeff Mallory, Michèle Slaton, Kirk Evans, Gregory P. Asner
Continent-wide tree fecundity driven by indirect climate effects
Indirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here we find from a synthesis of tree species in North
Authors
James S. Clark, Robert A. Andrus, Melaine Aubry-Kientz, Yves Bergeron, Michal Bogdziewicz, Don C. Bragg, Dale G. Brockway, Natalie L. Cleavitt, Susan Cohen, Benoit Courbaud, Robert Daley, Adrian Das, Michael Dietze, Timothy J. Fahey, Istem Fer, Jerry F. Franklin, Catherine A. Gehring, Gregory S. Gilbert, Catheryn H Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Ines Ibanez, Jill F. Johnstone, Christopher L. Kilner, Johannes MH Knops, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Kristin L Legg, Jordan Luongo, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Yassine Messaoud, Christopher M. Moore, Emily V. Moran, Orrin B Myers, Chase Nunez, Robert Parmenter, Scott Pearson, Renata Poulton Kamakura, Ethan Ready, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, Wiliam H Schlesinger, Amanda M Schwantes, Erin Shanahan, Shubhi Sharma, Michael A. Steele, Nathan L. Stephenson, Samantha Sutton, Jennifer J. Swenson, Margaret Swift, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, Kai Zhu, Roman Zlotin
Why is tree drought mortality so hard to predict?
Widespread tree mortality following droughts has emerged as an environmentally and economically devastating ‘ecological surprise’. It is well established that tree physiology is important in understanding drought-driven mortality; however, the accuracy of predictions based on physiology alone has been limited. We propose that complicating factors at two levels stymie predictions of drought-driven
Authors
Anna T Trugman, Leander D.L. Anderegg, William RL Anderegg, Adrian Das, Nathan L. Stephenson
poscrptR
poscrptR 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 conifers
This 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.
Science and Products
- Science
Forest health and drought response
Forests provide society with economically important and often irreplaceable goods and services, such as wood products, carbon sequestration, clean water, biodiversity, and recreational opportunities. Yet hotter droughts (droughts in which unusually high temperatures exacerbate the effects of low precipitation) are projected to increase in frequency and intensity in coming decades, potentially...Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?
The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. CSequoia and Kings Canyon Field Station
The 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.Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts
Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest
Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this immCan Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?
In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...Characterizing a link in the terrestrial carbon cycle: a global overview of individual tree mass growth
Forests sequester the majority of the terrestrial biosphere’s carbon and are key components of the global carbon cycle, potentially contributing substantial feedbacks to ongoing climatic changes. It is therefore remarkable that no consensus yet exists about the fundamental nature of tree mass growth (and thus carbon sequestration rate). Specifically, does tree mass growth rate increase, decrease, - Data
Assessment of Giant Sequoia Mortality and Regeneration within Burned Groves in Sequoia and Kings Canyon National Parks
Provided are data containing condition assessments on individual giant sequoia (Sequoiadendron giganteum; SEGI) stems and post-fire regeneration counts within Board Camp, Suwanee, New Oriole Lake, and a subset of Redwood Mountain groves of Sequoia and Kings Canyon national parks, respectively. Stem data contain condition-related attributes (e.g., spatial location, diameter breast height, status -Calibration and Validation Data and Model Coefficients for Mixed Conifer Vulnerability Project from Sequoia and Kings Canyon National Park 2015 to 2019
These datasets contain the attributes of individual trees located in and around Sequoia and Kings Canyon national parks. Attributes include remote sensing indices, terrain characteristics, and-- for the calibration data-- tree size and growth rates. Calibration data (mixedconifervulnerability_calibrationdataset.csv) were collected in long term research plots where trees are visited annually to cheSequoia and Yosemite National Parks Mortality and Fire Data (1990-2019) for Competition-Fire-Drought Interaction Analysis
This dataset records mortality-- including involvement of bark beetles-- and burn severity information for trees in long term forest dynamics plots in Sequoia National Park and Yosemite National Park that experienced fire. These data support the following publication: Furniss, T.J., Das, A.J., van Mantgem, P.J., Stephenson, N.L. and Lutz, J.A., 2021. Crowding, climate, and the case for sociData for Use in poscrptR Post-fire Conifer Regeneration Prediction Model
These 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, anForest Structure Data for Burned and Unburned Sites at Sequoia and Kings Canyon National Parks
These data represent tree diameter, species, mortality status, and plot attributes from 164 plots in Sequoia and Kings Canyon national parks, California. Plots were matched with local records of recent fire history to determine burn status and year burned if applicable. These data support the following publication: van Mantgem, P.J., Caprio, A.C., Stephenson, N.L. and Das, A.J., 2021. Forest RePost-fire conifer regeneration observations for National Forest land in California (2009 - 2017)
This data consists of presence/absence observations for post-fire conifer regeneration. The data also includes estimates of plot-level topography (slope, aspect), relativized differenced normalized burn ratio (RdNBR), post-fire climate, live basal area, and seed rain. These data support the following publication:Seed and Associated Tree Data from Long Term Research Plots in Sequoia and Yosemite national parks
This dataset was used as part of a continent-wide analysis of tree fecundity and its association with climate and tree size. This dataset consists of: plotinfo.csv, which contains basic attribute information for the field plots where the data were collected; seeddata.csv, which contains the data for seeds collected (how many, what type, etc.); trapxycoord.csv, which contains location and identificTree mortality in blue oak woodlands in Sequoia National Park during the extreme drought
These data were collected to quantify oak mortality during the 2014-2017 drought. 30 tenth hectare drought plots were established throughout the blue oak woodland of Sequoia National Park. Information on species, size, and mortality were collected for all standing trees in each plot. In addition, two long-term 2.25 ha plots were established, in which the same data were collected.Seedling and tree data from Sequoia National Park and Yosemite National Park
These tables include data from 25 long-term forest plots located in either Sequoia or Yosemite national park. Trees in these plots (established between 1982 and 2001) are censused annually for mortality and measured for diameter every 4 to 6 years. Plots were mostly 1 hectare (ha) in size (range 0.9 - 2.5 ha) and contained at least two 25 by 25 meter seedling sub-plots to monitor natural seedlingTree mortality in Sequoia National Park from 2004 to 2007 and during severe drought in 2014 to 2017
These data describe tree mortality and the factors associated with tree mortality for a variety of plots in Sequoia National Park. Most of the data were collected between 2014 and 2017 (during an extremely severe drought), along with some comparison data from 2004 to 2007. These data support the following publication: Stephenson, N.L., Das, A.J., Ampersee, N.J., Bulaon, B.M., and Yee, J.L.,Sequoia foliage dieback data from Sequoia National Park
These datasets provide spatially-explicit estimates of the magnitude of giant sequoia foliage dieback along selected trail corridors in Sequoia and Kings Canyon national parks, California, from 2014 through 2017. They additionally provide giant sequoia tree-ring measurements, through the year 1989, for two locations in the Giant Forest grove, Sequoia National Park, California.Mortality factors for dead trees from a subset of plots from the Sierra Nevada Forest Dynamics Plot Network from 1998 to 2010
This dataset was used to summarize and analyze the mortality factors recorded on dead trees in the Sierra Nevada Forest Dynamics Plot Network, which is managed by the Sequoia and Kings Canyon Field station of the U.S. Geological Survey's Western Ecological Research Center. Each row of the dataset represents an individual dead tree. These are dead trees that were recorded in the network from 1998 t - Publications
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Linking seed size and number to trait syndromes in trees
AimOur understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whether reproduction represents an independent dimensionAuthorsMichal Bogdziewicz, Marie-Claire Aravena Acuña, Robert A. Andrus, Davide Ascoli, Yves Bergeron, Daniel Brveiller, Thomas Boivin, Raul Bonal, Thomas Caignard, Maxime Cailleret, Rafael Calama, Sergio Donoso Calderon, J. Julio Camarero, Chia-Hao Chang-Yang, Jerome Chave, Francesco Chianucci, Natalie L. Cleavitt, Benoit Courbaud, Andrea Cutini, Thomas Curt, Adrian Das, Hendrik Davi, Nicolas Delpiere, Sylvain Delzon, Michael Dietze, Laurent Dormont, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzer, Cathryn H. Greenberg, Arthur Guignabert, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Valentin Journé, Thomas Kitzberger, Johannes M.H. Knops, Georges Kunstler, Richard Kobe, Jonathan G. A. Lageard, Jalene M. LaMontagne, Mateusz Ledwon, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Anders Marell, Eliot J.B. McIntire, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Shoji Naoe, Kyotaro Noguchi, Michio Oguro, Hiroko Kurokawa, Jean-Marc Ourcival, Robert Parmenter, Ignacio M. Perez-Ramos, Lukasz Piechnik, Tomasz Podgórski, John Poulsen, Tong Qiu, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, Pavel Šamonil, Jan Holik, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Mitsue Shibata, Shubhi Sharma, Miles Silman, Michael A. Steele, Jacob N. Straub, I-Fang Sun, Samantha Sutton, Jennifer J. Swenson, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Boyd Wright, S. Joseph Wright, Thomas G. Whitham, Kai Zhu, Jess K. Zimmerman, Magdalna Zywiec, James S. ClarkClimate change risks to global forest health: Emergence of unexpected events of elevated tree mortality worldwide
Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about climate change risks to global forest health. We currently lack both sufficient data and understanding to identify whether these observations represent a global trend towards increasing tree mortality. Here, we document events of sudden and unexpected elevated tree mortality folloAuthorsHenrik Hartmann, Ana Bastos, Adrian Das, Adriane Esquivel-Muelbert, William M Hammond, Jordi Martínez-Vilalta, Nate G. McDowell, Jennifer S. Powers, Thomas A. M. Pugh, Katinka X. Ruthrof, Craig D. AllenLimits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery
The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four maAuthorsTong Qiu, Robert Andrus, Marie-Claire Aravena Acuna, Davide Ascoli, Yves Bergeron, Roberta Berretti, Daniel Berveiller, Thomas Biovin, Raul Bonal, Don C. Bragg, Thomas Caignard, Rafael Calama, J. Julio Camarero, Chia-Huo Chang-Yang, Natalie L. Cleavitt, Benoit Courbaud, Francois Courbet, Thomas Curt, Adrian Das, Evangelia Daskalakou, Hendrik Davi, Nicolas Delpierre, Sylvain Delzon, Michael Dietze, Sergio Donoso Calderon, Laurent Dormont, Josep Maria Espelta, Timothy J. Fahey, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzner, Cathryn H. Greenberg, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Valentin Journé, Daisuke Kabeya, Christopher L. Kilner, Thomas Kitzberger, Johannes M. H. Knops, Richard K. Kobe, Georges Kunstler, Hiroko Kurokawa, Jonathan G. A. Lageard, Jalene LaMontagne, Mateusz Ledwon, Francois Lefevre, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Christopher M. Moore, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Kyotaro Noguchi, Jean-Marc Ourcival, Robert Parmenter, Ian Pearse, Ignacio M. Perez-Ramos, Lukasz Piechnik, John Poulsen, Renata Poulton-Kamakura, Miranda Redmond, Chantal D. Reid, Kyle C. Rodman, Francisco Rodrigues-Sanchez, Javier Sanguinetti, C. Lane Scher, Wiliam H Schlesinger, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Michael A. Steele, Nathan L. Stephenson, Jacob N. Straub, I-Fang Sun, Samantha Sutton, Jennifer J. Swenson, Margaret Swift, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas Wion, Boyd Wright, S. Joseph Wright, Kai Zhu, Jess Zimmermann, Roman Zlotin, Magdalena Zywiec, James S. ClarkGlobally, tree fecundity exceeds productivity gradients
Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250-fold increase in seed abundance from cold-dry to warm-wet climates, driven primarily by a 100-fold increase in seed production for a giveAuthorsValentin Journé, Robert A. Andrus, Marie-Claire Aravena Acuna, Davide Ascoli, Roberta Berretti, Daniel Berveiller, Michal Bogdziewicz, Thomas Boivin, Raul Bonal, Thomas Caignard, Rafael Calama, J. Julio Camarero, Chia-Hao Chang-Yang, Benoit Courbaud, Francois Courbet, Thomas Curt, Adrian Das, Evangelia Daskalakou, Hendrik Davi, Nicolas Delpierre, Sylvain Delzon, Michael Dietze, Sergio Donoso Calderon, Laurent Dormont, Josep Maria Espelta, Timothy J. Fahey, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Georg Gratzer, Cathryn H. Greenberg, Qinfeng Guo, Andrew Hacket-Pain, Arndt Hampe, Qingmin Han, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Jill F. Johnstone, Daisuke Kabeya, Roland Kays, Thomas Kitzberger, Johannes M. H. Knops, Richard K. Kobe, Georges Kunstler, Jonathan G. A. Lageard, Jalene M. LaMontagne, Theodor Leininger, Jean-Marc Limousin, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Christopher M. Moore, Emily V. Moran, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Kyotaro Noguchi, Jean-Marc Ourcival, Robert Parmenter, Ian Pearse, Ignacio M. Perez-Ramos, Lukasz Piechnik, John Poulsen, Renata Poulton-Kamakura, Tong Qiu, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, Francisco Rodriguez-Sanchez, Javier D Sanguinetti, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Michael A. Steele, Nathan L. Stephenson, Jacob N. Straub, Jennifer J. Swenson, Margaret Swift, Peter A. Thomas, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Boyd Wright, S. Joseph Wright, Kai Zhu, Jess K. Zimmerman, Roman Zlotin, Magdalena Zywiec, James S. ClarkNorth American tree migration paced by climate in the West, lagging in the East
Tree fecundity and recruitment have not yet been quantified at scales needed to anticipate biogeographic shifts in response to climate change. By separating their responses, this study shows coherence across species and communities, offering the strongest support to date that migration is in progress with regional limitations on rates. The southeastern continent emerges as a fecundity hotspot, butAuthorsShubhi Sharma, Robert Andrus, Yves Bergeron, Michal Bogdziewicz, Don C. Bragg, Dale G. Brockway, Natalie L. Cleavitt, Benoit Courbaud, Adrian Das, Michael Dietze, Timothy J. Fahey, Jerry F. Franklin, Gilbert S. Gregory, Cathryn H. Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Ines Ibanez, Jill F. Johnstone, Christopher L. Kilner, Johannes M. H. Knops, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Diana Macias, Emily V. Moran, Jonathan A. Myers, Robert Parmenter, Ian Pearse, Renata Poulton-Kamakura, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, William H. Schlesinger, Michael A. Steele, Nathan L. Stephenson, Jennifer J. Swenson, Margaret Swift, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, Christopher W. Woodall, Roman Zlotin, James S. ClarkEmpirically validated drought vulnerability mapping in the mixed conifer forests of the Sierra Nevada
Severe droughts are predicted to become more frequent in the future, and the consequences of such droughts on forests can be dramatic, resulting in massive tree mortality, rapid change in forest structure and composition, and substantially increased risk of catastrophic fire. Forest managers have tools at their disposal to try to mitigate these effects but are often faced with limited resources, fAuthorsAdrian Das, Michèle R Slaton, Jeffrey Mallory, Gregory P. Asner, Roberta E. Martin, Paul HardwickCrowding, climate, and the case for social distancing among trees
In an emerging era of megadisturbance, bolstering forest resilience to wildfire, insects, and drought has become a central objective in many western forests. Climate has received considerable attention as a driver of these disturbances, but few studies have examined the complexities of climate–vegetation–disturbance interactions. Current strategies for creating resilient forests often rely on retrAuthorsTucker J. Furniss, Adrian Das, Phillip J. van Mantgem, Nathan L. Stephenson, James A. LutzForest resistance to extended drought enhanced by prescribed fire in low elevation forests of the Sierra Nevada
Prescribed fire reduces fire hazards by removing dead and live fuels (small trees and shrubs). Reductions in forest density following prescribed fire treatments (often in concert with mechanical treatments) may also lessen competition so that residual trees might be more likely to survive when confronted with additional stressors, such as drought. The current evidence for these effects is mixed anAuthorsPhillip J. van Mantgem, Anthony C. Caprio, Nathan L. Stephenson, Adrian DasNonlinear shifts in infectious rust disease due to climate change
Range shifts of infectious plant disease are expected under climate change. As plant diseases move, emergent abiotic-biotic interactions are predicted to modify their distributions, leading to unexpected changes in disease risk. Evidence of these complex range shifts due to climate change, however, remains largely speculative. Here, we combine a long-term study of the infectious tree disease, whitAuthorsJoan Dudney, Claire Willing, Adrian Das, Andrew M. Latimer, Jonathan C B Nesmith, John J. BattlesMapping the vulnerability of giant sequoias after extreme drought in California using remote sensing
Between 2012 and 2016, California suffered one of the most severe droughts on record. During this period Sequoiadendron giganteum (giant sequoias) in the Sequoia and Kings Canyon National Parks (SEKI), California, USA experienced canopy water content (CWC) loss, unprecedented foliage senescence, and, in a few cases, death. We present an assessment of the vulnerability of giant sequoia populationsAuthorsAndres Baeza, Roberta E. Martin, Nathan L. Stephenson, Adrian Das, Paul Hardwick, Koren R. Nydick, Jeff Mallory, Michèle Slaton, Kirk Evans, Gregory P. AsnerContinent-wide tree fecundity driven by indirect climate effects
Indirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here we find from a synthesis of tree species in NorthAuthorsJames S. Clark, Robert A. Andrus, Melaine Aubry-Kientz, Yves Bergeron, Michal Bogdziewicz, Don C. Bragg, Dale G. Brockway, Natalie L. Cleavitt, Susan Cohen, Benoit Courbaud, Robert Daley, Adrian Das, Michael Dietze, Timothy J. Fahey, Istem Fer, Jerry F. Franklin, Catherine A. Gehring, Gregory S. Gilbert, Catheryn H Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Ines Ibanez, Jill F. Johnstone, Christopher L. Kilner, Johannes MH Knops, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Kristin L Legg, Jordan Luongo, James A. Lutz, Diana Macias, Eliot J. B. McIntire, Yassine Messaoud, Christopher M. Moore, Emily V. Moran, Orrin B Myers, Chase Nunez, Robert Parmenter, Scott Pearson, Renata Poulton Kamakura, Ethan Ready, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, Wiliam H Schlesinger, Amanda M Schwantes, Erin Shanahan, Shubhi Sharma, Michael A. Steele, Nathan L. Stephenson, Samantha Sutton, Jennifer J. Swenson, Margaret Swift, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, Kai Zhu, Roman ZlotinWhy is tree drought mortality so hard to predict?
Widespread tree mortality following droughts has emerged as an environmentally and economically devastating ‘ecological surprise’. It is well established that tree physiology is important in understanding drought-driven mortality; however, the accuracy of predictions based on physiology alone has been limited. We propose that complicating factors at two levels stymie predictions of drought-drivenAuthorsAnna T Trugman, Leander D.L. Anderegg, William RL Anderegg, Adrian Das, Nathan L. Stephenson - Software
poscrptR
poscrptR 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 conifers
This 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. - News