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
Effects of postfire climate and seed availability on postfire conifer regeneration
Compounding effects of white pine blister rust, mountain pine beetle, and fire threaten four white pine species
Mortality predispositions of conifers across western USA
Height-related changes in forest composition, not tree vulnerability, explain increasing mortality with height during an extreme drought
The Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire
The influence of pre-fire growth patterns on post-fire tree mortality for common conifers in western U.S. parks
Tree mortality in blue oak woodland during extreme drought in Sequoia National Park, California
Size matters, but not consistently
Negative impacts of summer heat on Sierra Nevada tree seedlings
Which trees die during drought? The key role of insect host-tree selection
Pre‐fire drought and competition mediate post‐fire conifer mortality in western U.S. National Parks
Science and Products
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Filter Total Items: 92
Effects of postfire climate and seed availability on postfire conifer regeneration
Large, severe fires are becoming more frequent in many forest types across the western United States and have resulted in tree mortality across tens of thousands of hectares. Conifer regeneration in these areas is limited because seeds must travel long distances to reach the interior of large burned patches and establishment is jeopardized by increasingly hot and dry conditions. To better inform pAuthorsJoseph A E Stewart, Phillip J. van Mantgem, Derek J N Young, Kristen L. Shive, Haiganoush K. Preisler, Adrian Das, Nathan L. Stephenson, Jon Keeley, Hugh D. Safford, Micah C. Wright, Kevin R Welch, James H. ThorneCompounding effects of white pine blister rust, mountain pine beetle, and fire threaten four white pine species
Invasive pathogens and bark beetles have caused precipitous declines of various tree species around the globe. Here, we characterized long‐term patterns of mountain pine beetle (Dendroctonus ponderosae; MPB) attacks and white pine blister rust, an infectious tree disease caused by the pathogen, Cronartium ribicola. We focused on four dominant white pine host species in Sequoia and Kings Canyon NatAuthorsJoan C Dudney, Jonathan C B Nesmith, Matthew Cahill, Jennifer E Cribbs, Dan M Duriscoe, Adrian Das, Nathan L. Stephenson, John J. BattlesMortality predispositions of conifers across western USA
Conifer mortality rates are increasing in western North America, but the physiological mechanisms underlying this trend are not well understood.We examined tree‐ring‐based radial growth along with stable carbon (C) and oxygen (O) isotope composition (δ13C and δ18O, respectively) of dying and surviving conifers at eight old‐growth forest sites across a strong moisture gradient in the western USA toAuthorsWenzhi Wang, Nathan B. English, Charlotte Grossiord, Arthur Gessler, Adrian Das, Nathan L. Stephenson, Christopher H. Baisan, Craig D. Allen, Nate G. McDowellHeight-related changes in forest composition, not tree vulnerability, explain increasing mortality with height during an extreme drought
Recently, Stovall et al.1 (hereafter SSY) showed that during an extreme drought, remotely sensed mortality of tall trees was more than double that of short trees. They interpreted this to be a consequence of inherently greater hydraulic vulnerability of tall trees, and suggested that tall-tree vulnerability should thus generalize more broadly. Here we reassess their conclusions using contemporanAuthorsNathan L. Stephenson, Adrian DasThe Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire
Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes recordsAuthorsC. Alina Cansler, Sharon M. Hood, J. Morgan Varner, Phillip J. van Mantgem, Michelle C. Agne, Robert A. Andrus, Matthew P. Ayres, Bruce D. Ayres, Jonathan D. Bakker, Michael A. Battaglia, Barbara J. Bentz, Carolyn R. Breece, James K. Brown, Daniel R. Cluck, Tom W. Coleman, R. Gregory Corace, W. Wallace Covington, Douglas S. Cram, James B. Cronan, Joseph E. Crouse, Adrian Das, Ryan S. Davis, Darci M. Dickinson, Stephen A Fitzgerald, Peter Z. Fule, Lisa M. Ganio, Lindsay M. Grayson, Charles B. Halpern, Jim L. Hanula, Brian J. Harvey, J. Kevin Hiers, David W. Huffman, MaryBeth Keifer, Tara L. Keyser, Leda N. Kobziar, Thomas E. Kolb, Crystal A. Kolden, Karen E. Kopper, Jason R. Kreitler, Jesse K. Kreye, Andrew M. Latimer, Andrew P. Lerch, Maria J. Lombardero, Virginia L. McDaniel, Charles W. McHugh, Joel D. McMillin, Jason J. Moghaddas, Joseph J. O'Brien, Daniel D. B. Perrakis, David W. Peterson, Susan J. Pritchard, Robert A. Progar, Kenneth F. Raffa, Elizabeth D. Reinhardt, Joseph C. Restaino, John P. Roccaforte, Brendan M. Rogers, Kevin C. Ryan, Hugh D. Safford, Alyson E. Santoro, Timothy M. Shearman, Alice M. Shumate, Carolyn H. Sieg, Sheri L. Smith, Rebecca J. Smith, Nathan L. Stephenson, Mary Stuever, Jens Stevens, Michael T. Stoddard, Walter G. Thies, Nicole M. Vaillant, Shelby A. Weiss, Douglas J. Westlind, Travis J. Woolley, Micah C. WrightThe 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-fireAuthorsPhillip van Mantgem, Donald A. Falk, Emma C. Williams, Adrian J. Das, Nathan L. StephensonTree 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 severiAuthorsAdrian J. Das, Nicholas J. Ampersee, Anne Hopkins Pfaff, Nathan L. Stephenson, Tedmund J Swiecki, Elizabeth A Bernhardt, Patricia Haggerty, Koren R. NydickSize 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 interpretAuthorsNathan L. Stephenson, Adrian J. DasNegative 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 thAuthorsEmily V. Moran, Adrian J. Das, Jon Keeley, Nathan L. StephensonWhich 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: outbreakingAuthorsNathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Beverly M Bulaon, Julie L. YeePre‐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. Stephenson - Software
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