Nathan Stephenson
Dr. Nathan Stephenson is a Scientist Emeritus at the Western Ecological Research Center.
Earth’s vast forests provide human communities with irreplaceable goods and services such as carbon sequestration, hydrologic regulation, clean water, biodiversity, critical wildlife habitat, wood products, and recreational and spiritual opportunities. An overarching goal of Dr. Nathan Stephenson's research is to improve scientists' and land managers' ability to understand, forecast, and adapt to the effects of ongoing global changes – particularly changing climatic and disturbance regimes – on forests.
Accordingly, most of his research falls in three broad, complementary themes: (1) improving mechanistic understanding of forest and carbon dynamics, (2) detection, attribution, and interpretation of forest changes, and (3) adaptations to rapid global changes. The last theme extends well beyond forests, to natural areas in general.
RESEARCH INTERESTS
- Forest ecology
- Global change biology
- Climate change
- Fire ecology
- Natural areas management
- Adaptation
EDUCATION
- Ph.D., Ecology and Systematics, Cornell University, 1988
- B.S., Biological Sciences, University of California, Irvine, 1979
Science and Products
Pre‐fire drought and competition mediate post‐fire conifer mortality in western U.S. National Parks
Leaf to landscape responses of giant sequoia to hotter drought: An introduction and synthesis for the special section
Remote measurement of canopy water content in giant sequoias (Sequoiadendron giganteum) during drought
Navigating translational ecology: Creating opportunities for scientist participation
Landscape-scale variation in canopy water content of giant sequoias during drought
Foundations of translational ecology
Patterns and correlates of giant sequoia foliage dieback during California’s 2012–2016 hotter drought
What mediates tree mortality during drought in the southern Sierra Nevada?
Seasonal and diel environmental conditions predict western pond turtle (Emys marmorata) behavior at a perennial and an ephemeral stream in Sequoia National Park, California
Why do trees die? Characterizing the drivers of background tree mortality
Does prescribed fire promote resistance to drought in low elevation forests of the Sierra Nevada, California, USA?
Montane Forests
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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 commAuthorsPhillip J. van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. StephensonLeaf 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 measAuthorsKoren 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-KaganRemote 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 physiologicAuthorsRoberta 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. StephensonNavigating translational ecology: Creating opportunities for scientist participation
Interest in translational ecology (TE) – a research approach that yields useful scientific outcomes through ongoing collaboration between scientists and stakeholders – is growing among both of these groups. Translational ecology brings together participants from different cultures and with different professional incentives. We address ways to cultivate a culture of TE, such as investing time in unAuthorsLauren M. Hallett, Toni Lyn Morelli, Leah R. Gerber, Max A. Moritz, Mark W. Schwartz, Nathan L. Stephenson, Jennifer L. Tank, Matthew A. Williamson, Connie A. WoodhouseLandscape-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 successiveAuthorsTarin Paz-Kagan, Nicolas R. Vaughn, Roberta E. Martin, Philip G. Brodrick, Nathan L. Stephenson, Adrian Das, Koren R. Nydick, Gregory P. AsnerFoundations of translational ecology
Ecologists who specialize in translational ecology (TE) seek to link ecological knowledge to decision making by integrating ecological science with the full complement of social dimensions that underlie today's complex environmental issues. TE is motivated by a search for outcomes that directly serve the needs of natural resource managers and decision makers. This objective distinguishes it from bAuthorsCarolyn A. F. Enquist, Stephen T. Jackson, Gregg M. Garfin, Frank W. Davis, Leah R. Gerber, Jeremy Littell, Jennifer L. Tank, Adam Terando, Tamara U. Wall, Benjamin S. Halpern, J. Kevin Hiers, Toni L. Morelli, Elizabeth McNie, Nathan L. Stephenson, Matthew A. Williamson, Connie A. Woodhouse, Laurie Yung, Mark W. Brunson, Kimberly R. Hall, Lauren M. Hallett, Dawn M. Lawson, Max A. Moritz, Koren R. Nydick, Amber Pairis, Andrea J. Ray, Claudia M. Regan, Hugh D. Safford, Mark W. Schwartz, M. Rebecca ShawPatterns 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 apparentlyAuthorsNathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Kathleen G. Cahill, Anthony C. Caprio, John E. Sanders, A. Park WilliamsWhat mediates tree mortality during drought in the southern Sierra Nevada?
Severe drought has the potential to cause selective mortality within a forest, thereby inducing shifts in forest species composition. The southern Sierra Nevada foothills and mountains of California have experienced extensive forest dieback due to drought stress and insect outbreak. We used high-fidelity imaging spectroscopy (HiFIS) and light detection and ranging (LiDAR) from the Carnegie AirbornAuthorsTarin Paz-Kagan, Philip Brodrick, Nicholas R. Vaughn, Adrian J. Das, Nathan L. Stephenson, Koren R. Nydick, Gregory P. AsnerSeasonal and diel environmental conditions predict western pond turtle (Emys marmorata) behavior at a perennial and an ephemeral stream in Sequoia National Park, California
Managers making decisions may benefit from a well-informed understanding of a species' population size and trends. Given the cryptic nature and habitat characteristics of the western pond turtle (Emys marmorata), however, imperfect detection may be high and population estimates are frequently varied and unreliable. As a case study to investigate this issue, we used temperature dataloggers to examiAuthorsGabrielle Ruso, Erik Meyer, Adrian J. DasWhy do trees die? Characterizing the drivers of background tree mortality
The drivers of background tree mortality rates—the typical low rates of tree mortality found in forests in the absence of acute stresses like drought—are central to our understanding of forest dynamics, the effects of ongoing environmental changes on forests, and the causes and consequences of geographical gradients in the nature and strength of biotic interactions. To shed light on factors contriAuthorsAdrian J. Das, Nathan L. Stephenson, Kristin P. DavisDoes prescribed fire promote resistance to drought in low elevation forests of the Sierra Nevada, California, USA?
Prescribed fire is a primary tool used to restore western forests following more than a century of fire exclusion, reducing fire hazard by removing dead and live fuels (small trees and shrubs). It is commonly assumed that the reduced forest density following prescribed fire also reduces competition for resources among the remaining trees, so that the remaining trees are more resistant (more likelAuthorsPhillip J. van Mantgem, Anthony C. Caprio, Nathan L. Stephenson, Adrian J. DasMontane Forests
This long-anticipated reference and sourcebook for California’s remarkable ecological abundance provides an integrated assessment of each major ecosystem type—its distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and prAuthorsMalcolm P. North, Brandon M. Collins, Hugh D. Safford, Nathan L. Stephenson - Software
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