Adrian Das
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
Filter Total Items: 14
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Filter Total Items: 53
The influence of pre-fire growth patterns on post-fire tree mortality for common conifers in western U.S. parks
Fire severity in forests is often defined in terms of post-fire tree mortality, yet the influences on tree mortality following fire are not fully understood. For trees that are not killed immediately by severe fire injury, pre-fire growth may partially predict post-fire mortality probabilities for conifers of the western U.S. Here, we consider the influence of multiple growth patterns on post-fire
Authors
Phillip van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. Stephenson
Tree mortality in blue oak woodland during extreme drought in Sequoia National Park, California
Blue oak woodlands in California have been a focus of conservation concern for many years. Numerous studies have found that existing seedling and sapling numbers are inadequate to sustain current populations, and recent work has suggested that blue oak woodlands might be particularly vulnerable to a warming climate. California has recently experienced a drought of historically unprecedented severi
Authors
Adrian J. Das, Nicholas J. Ampersee, Anne Hopkins Pfaff, Nathan L. Stephenson, Tedmund J Swiecki, Elizabeth A Bernhardt, Patricia Haggerty, Koren R. Nydick
Size matters, but not consistently
E. Pennisi (“Forest giants are the trees most at risk,” News, 6 September, p. 962) interprets presentations of three studies as suggesting that “for trees, size is not strength, and forest giants are disproportionately vulnerable.” However, this conclusion is not well supported.
The observation that lightning is a major cause of large-tree mortality on Barro Colorado Island (BCI) is best interpret
Authors
Nathan L. Stephenson, Adrian J. Das
Negative impacts of summer heat on Sierra Nevada tree seedlings
Understanding the response of forests to climate change is important for predicting changes in biodiversity and ecosystem services, including carbon storage. Seedlings represent a key demographic stage in these responses, because seedling establishment is necessary for population persistence and spread, and because the conditions allowing seedlings to survive and grow are often more restrictive th
Authors
Emily V. Moran, Adrian J. Das, Jon Keeley, Nathan L. Stephenson
Which trees die during drought? The key role of insect host-tree selection
1. During drought, the tree subpopulations (such as size or vigor classes) that suffer disproportionate mortality can be conceptually arrayed along a continuum defined by the actions of biotic agents, particularly insects. At one extreme, stress dominates: insects are absent or simply kill the most physiologically stressed trees. At the opposite extreme, host selection dominates: outbreaking
Authors
Nathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Beverly M Bulaon, Julie L. Yee
Early-warning signals of individual tree mortality based on annual radial growth
Tree mortality is a key driver of forest dynamics and its occurrence is projected to increase in the future due to climate change. Despite recent advances in our understanding of the physiological mechanisms leading to death, we still lack robust indicators of mortality risk that could be applied at the individual tree scale. Here, we build on a previous contribution exploring the differences in g
Authors
Maxime Cailleret, Vasilis Dakos, Steven Jansen, Elisabeth M. R. Robert, Tuomas Aakala, Mariano M. Amoroso, Joe A. Antos, Christof Bigler, Harald Bugmann, Marco Caccianaga, Jesus-Julio Camarero, Paolo Cherubini, Marie R. Coyea, Katarina Cufar, Adrian J. Das, Hendrik Davi, Guillermo Gea-Izquierdo, Sten Gillner, Laurel J. Haavik, Henrik Hartmann, Ana-Maria Heres, Kevin R. Hultine, Pavel Janda, Jeffrey M. Kane, Viachelsav I. Kharuk, Thomas Kitzberger, Tamir Klein, Tom Levanic, Juan-Carlos Linares, Fabio Lombardi, Harri Makinen, Ilona Mészáros, Juha M. Metsaranta, Walter Oberhuber, Andreas Papadopoulos, Any Mary Petritan, Brigitte Rohner, Gabriel Sanguesa-Barreda, Jeremy M. Smith, Amanda B. Stan, Dejan B. Stojanovic, Maria-Laura Suarez, Miroslav Svoboda, Volodymyr Trotsiuk, Ricardo Villalba, Alana R. Westwood, Peter H. Wyckoff, Jordi Martínez-Vilalta
Pre‐fire drought and competition mediate post‐fire conifer mortality in western U.S. National Parks
Tree mortality is an important outcome of many forest fires. Extensive tree injuries from fire may lead directly to mortality, but environmental and biological stressors may also contribute to tree death. However, there is little evidence showing how the combined effects of two common stressors, drought and competition, influence post‐fire mortality. Geographically broad observations of three comm
Authors
Phillip J. van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. Stephenson
Leaf to landscape responses of giant sequoia to hotter drought: An introduction and synthesis for the special section
Hotter droughts are becoming more common as climate change progresses, and they may already have caused instances of forest dieback on all forested continents. Learning from hotter droughts, including where on the landscape forests are more or less vulnerable to these events, is critical to help resource managers proactively prepare for the future. As part of our Leaf to Landscape Project, we meas
Authors
Koren R. Nydick, Nathan L. Stephenson, Anthony R. Ambrose, Gregory P. Asner, Wendy L. Baxter, Adrian J. Das, Todd E. Dawson, Roberta E. Martin, Tarin Paz-Kagan
Remote measurement of canopy water content in giant sequoias (Sequoiadendron giganteum) during drought
California experienced severe drought from 2012 to 2016, and there were visible changes in the forest canopy throughout the State. In 2014, unprecedented foliage dieback was recorded in giant sequoia (Sequoiadendron giganteum) trees in Sequoia National Park, in the southern California Sierra Nevada mountains. Although visible changes in sequoia canopies can be recorded, biochemical and physiologic
Authors
Roberta E. Martin, Gregory P. Asner, Emily Francis, Anthony Ambrose, Wendy Baxter, Adrian J. Das, Nicolas R. Vaughn, Tarin Paz-Kagan, Todd E. Dawson, Koren R. Nydick, Nathan L. Stephenson
Individual species–area relationships in temperate coniferous forests
QuestionsWhat drives individual species–area relationships in temperate coniferous forests?LocationTwo 25.6‐ha forest plots on the Pacific Slope of North America, one in California, and one in Washington State.MethodsWe mapped all trees ≥1 cm in diameter and examined tree species diversity of their local neighbourhoods by calculating the individual species–area relationship for each species and fo
Authors
Adrian J. Das, Andrew J. Larson, James A. Lutz
Landscape-scale variation in canopy water content of giant sequoias during drought
Recent drought (2012–2016) caused unprecedented foliage dieback in giant sequoias (Sequoiadendron giganteum), a species endemic to the western slope of the southern Sierra Nevada in central California. As part of an effort to understand and map sequoia response to droughts, we studied the patterns of remotely sensed canopy water content (CWC), both within and among sequoia groves in two successive
Authors
Tarin Paz-Kagan, Nicolas R. Vaughn, Roberta E. Martin, Philip G. Brodrick, Nathan L. Stephenson, Adrian Das, Koren R. Nydick, Gregory P. Asner
Patterns and correlates of giant sequoia foliage dieback during California’s 2012–2016 hotter drought
Hotter droughts – droughts in which unusually high temperatures exacerbate the effects of low precipitation – are expected to increase in frequency and severity in coming decades, challenging scientists and managers to identify which parts of forested landscapes may be most vulnerable. In 2014, in the middle of California’s historically unprecedented 2012–2016 hotter drought, we noticed apparently
Authors
Nathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Kathleen G. Cahill, Anthony C. Caprio, John E. Sanders, A. Park Williams
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 53
The influence of pre-fire growth patterns on post-fire tree mortality for common conifers in western U.S. parks
Fire severity in forests is often defined in terms of post-fire tree mortality, yet the influences on tree mortality following fire are not fully understood. For trees that are not killed immediately by severe fire injury, pre-fire growth may partially predict post-fire mortality probabilities for conifers of the western U.S. Here, we consider the influence of multiple growth patterns on post-fire
Authors
Phillip van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. Stephenson
Tree mortality in blue oak woodland during extreme drought in Sequoia National Park, California
Blue oak woodlands in California have been a focus of conservation concern for many years. Numerous studies have found that existing seedling and sapling numbers are inadequate to sustain current populations, and recent work has suggested that blue oak woodlands might be particularly vulnerable to a warming climate. California has recently experienced a drought of historically unprecedented severi
Authors
Adrian J. Das, Nicholas J. Ampersee, Anne Hopkins Pfaff, Nathan L. Stephenson, Tedmund J Swiecki, Elizabeth A Bernhardt, Patricia Haggerty, Koren R. Nydick
Size matters, but not consistently
E. Pennisi (“Forest giants are the trees most at risk,” News, 6 September, p. 962) interprets presentations of three studies as suggesting that “for trees, size is not strength, and forest giants are disproportionately vulnerable.” However, this conclusion is not well supported.
The observation that lightning is a major cause of large-tree mortality on Barro Colorado Island (BCI) is best interpret
Authors
Nathan L. Stephenson, Adrian J. Das
Negative impacts of summer heat on Sierra Nevada tree seedlings
Understanding the response of forests to climate change is important for predicting changes in biodiversity and ecosystem services, including carbon storage. Seedlings represent a key demographic stage in these responses, because seedling establishment is necessary for population persistence and spread, and because the conditions allowing seedlings to survive and grow are often more restrictive th
Authors
Emily V. Moran, Adrian J. Das, Jon Keeley, Nathan L. Stephenson
Which trees die during drought? The key role of insect host-tree selection
1. During drought, the tree subpopulations (such as size or vigor classes) that suffer disproportionate mortality can be conceptually arrayed along a continuum defined by the actions of biotic agents, particularly insects. At one extreme, stress dominates: insects are absent or simply kill the most physiologically stressed trees. At the opposite extreme, host selection dominates: outbreaking
Authors
Nathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Beverly M Bulaon, Julie L. Yee
Early-warning signals of individual tree mortality based on annual radial growth
Tree mortality is a key driver of forest dynamics and its occurrence is projected to increase in the future due to climate change. Despite recent advances in our understanding of the physiological mechanisms leading to death, we still lack robust indicators of mortality risk that could be applied at the individual tree scale. Here, we build on a previous contribution exploring the differences in g
Authors
Maxime Cailleret, Vasilis Dakos, Steven Jansen, Elisabeth M. R. Robert, Tuomas Aakala, Mariano M. Amoroso, Joe A. Antos, Christof Bigler, Harald Bugmann, Marco Caccianaga, Jesus-Julio Camarero, Paolo Cherubini, Marie R. Coyea, Katarina Cufar, Adrian J. Das, Hendrik Davi, Guillermo Gea-Izquierdo, Sten Gillner, Laurel J. Haavik, Henrik Hartmann, Ana-Maria Heres, Kevin R. Hultine, Pavel Janda, Jeffrey M. Kane, Viachelsav I. Kharuk, Thomas Kitzberger, Tamir Klein, Tom Levanic, Juan-Carlos Linares, Fabio Lombardi, Harri Makinen, Ilona Mészáros, Juha M. Metsaranta, Walter Oberhuber, Andreas Papadopoulos, Any Mary Petritan, Brigitte Rohner, Gabriel Sanguesa-Barreda, Jeremy M. Smith, Amanda B. Stan, Dejan B. Stojanovic, Maria-Laura Suarez, Miroslav Svoboda, Volodymyr Trotsiuk, Ricardo Villalba, Alana R. Westwood, Peter H. Wyckoff, Jordi Martínez-Vilalta
Pre‐fire drought and competition mediate post‐fire conifer mortality in western U.S. National Parks
Tree mortality is an important outcome of many forest fires. Extensive tree injuries from fire may lead directly to mortality, but environmental and biological stressors may also contribute to tree death. However, there is little evidence showing how the combined effects of two common stressors, drought and competition, influence post‐fire mortality. Geographically broad observations of three comm
Authors
Phillip J. van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. Stephenson
Leaf to landscape responses of giant sequoia to hotter drought: An introduction and synthesis for the special section
Hotter droughts are becoming more common as climate change progresses, and they may already have caused instances of forest dieback on all forested continents. Learning from hotter droughts, including where on the landscape forests are more or less vulnerable to these events, is critical to help resource managers proactively prepare for the future. As part of our Leaf to Landscape Project, we meas
Authors
Koren R. Nydick, Nathan L. Stephenson, Anthony R. Ambrose, Gregory P. Asner, Wendy L. Baxter, Adrian J. Das, Todd E. Dawson, Roberta E. Martin, Tarin Paz-Kagan
Remote measurement of canopy water content in giant sequoias (Sequoiadendron giganteum) during drought
California experienced severe drought from 2012 to 2016, and there were visible changes in the forest canopy throughout the State. In 2014, unprecedented foliage dieback was recorded in giant sequoia (Sequoiadendron giganteum) trees in Sequoia National Park, in the southern California Sierra Nevada mountains. Although visible changes in sequoia canopies can be recorded, biochemical and physiologic
Authors
Roberta E. Martin, Gregory P. Asner, Emily Francis, Anthony Ambrose, Wendy Baxter, Adrian J. Das, Nicolas R. Vaughn, Tarin Paz-Kagan, Todd E. Dawson, Koren R. Nydick, Nathan L. Stephenson
Individual species–area relationships in temperate coniferous forests
QuestionsWhat drives individual species–area relationships in temperate coniferous forests?LocationTwo 25.6‐ha forest plots on the Pacific Slope of North America, one in California, and one in Washington State.MethodsWe mapped all trees ≥1 cm in diameter and examined tree species diversity of their local neighbourhoods by calculating the individual species–area relationship for each species and fo
Authors
Adrian J. Das, Andrew J. Larson, James A. Lutz
Landscape-scale variation in canopy water content of giant sequoias during drought
Recent drought (2012–2016) caused unprecedented foliage dieback in giant sequoias (Sequoiadendron giganteum), a species endemic to the western slope of the southern Sierra Nevada in central California. As part of an effort to understand and map sequoia response to droughts, we studied the patterns of remotely sensed canopy water content (CWC), both within and among sequoia groves in two successive
Authors
Tarin Paz-Kagan, Nicolas R. Vaughn, Roberta E. Martin, Philip G. Brodrick, Nathan L. Stephenson, Adrian Das, Koren R. Nydick, Gregory P. Asner
Patterns and correlates of giant sequoia foliage dieback during California’s 2012–2016 hotter drought
Hotter droughts – droughts in which unusually high temperatures exacerbate the effects of low precipitation – are expected to increase in frequency and severity in coming decades, challenging scientists and managers to identify which parts of forested landscapes may be most vulnerable. In 2014, in the middle of California’s historically unprecedented 2012–2016 hotter drought, we noticed apparently
Authors
Nathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Kathleen G. Cahill, Anthony C. Caprio, John E. Sanders, A. Park Williams