John B Bradford, Ph.D.
John Bradford is a Research Ecologist with the USGS Northwest Climate Adaptation Science Center. John studies dryland ecosystems in the context of global change and works with resource managers to identify adaptive strategies for sustaining these ecosystems in a changing world.
John focuses on understanding how changing climate, disturbances, and land use influence dryland vegetation, plant communities, and ecosystem services. He is currently engaged in the broad topics of ecohydrology and dryland sustainability in the western U.S. and has projects examining a) the potential influence of changing climatic conditions on the distribution and regeneration potential of trees and shrubs in the intermountain western U.S., b) strategies for understanding and enhancing dryland ecosystem resilience to changing climate and drought patterns, and c) ecosystem water balance and patterns of plant-available soil water in dryland regions.
Professional Experience
2011- Present: Research Ecologist - US Geological Survey, Southwest Biological Science Center, Flagstaff, AZ
2006 - 2011: Research Ecologist - USDA Forest Service, North Central Research Station, Grand Rapids, MN
2004 - 2006: Research Ecologist (Postdoctoral) - USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO
Education and Certifications
2004 - Ph.D., Ecology, Colorado State University
1996 - B.A., Biology, Cornell University
Science and Products
Sagebrush, greater sage-grouse, and the occurrence and importance of forbs
Seed bank and big sagebrush plant community composition in a range margin for big sagebrush
Total belowground carbon flux in subalpine forests is related to leaf area index, soil nitrogen, and tree height
Predicting tree biomass growth in the temperate-boreal ecotone: is tree size, age, competition or climate response most important?
Mid-latitude shrub steppe plant communities: Climate change consequences for soil water resources
A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration
Does the stress-gradient hypothesis hold water? Disentangling spatial and temporal variation in plant effects on soil moisture in dryland systems
The integrated rangeland fire management strategy actionable science plan
Growth-climate relationships across topographic gradients in the northern Great Lakes
LiDAR based prediction of forest biomass using hierarchical models with spatially varying coefficients
Desert grassland responses to climate and soil moisture suggest divergent vulnerabilities across the southwestern United States
Scale dependence of disease impacts on quaking aspen (Populus tremuloides) mortality in the southwestern United States
Science and Products
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Sagebrush, greater sage-grouse, and the occurrence and importance of forbs
Big sagebrush (Artemisia tridentata Nutt.) ecosystems provide habitat for sagebrush-obligate wildlife species such as the Greater Sage-Grouse (Centrocercus urophasianus). The understory of big sagebrush plant communities is composed of grasses and forbs that are important sources of cover and food for wildlife. The grass component is well described in the literature, but the composition, abundanceAuthorsVictoria E. Pennington, Daniel R. Schlaepfer, Jeffrey L. Beck, John B. Bradford, Kyle A. Palmquist, William K. LauenrothSeed bank and big sagebrush plant community composition in a range margin for big sagebrush
The potential influence of seed bank composition on range shifts of species due to climate change is unclear. Seed banks can provide a means of both species persistence in an area and local range expansion in the case of increasing habitat suitability, as may occur under future climate change. However, a mismatch between the seed bank and the established plant community may represent an obstacle tAuthorsTrace E. Martyn, John B. Bradford, Daniel R. Schlaepfer, Ingrid C. Burke, William K. LaurenrothTotal belowground carbon flux in subalpine forests is related to leaf area index, soil nitrogen, and tree height
In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynAuthorsErin Michele Berryman, Michael G. Ryan, John B. Bradford, Todd Hawbaker, R. BirdseyPredicting tree biomass growth in the temperate-boreal ecotone: is tree size, age, competition or climate response most important?
As global temperatures rise, variation in annual climate is also changing, with unknown consequences for forest biomes. Growing forests have the ability to capture atmospheric CO2and thereby slow rising CO2 concentrations. Forests’ ongoing ability to sequester C depends on how tree communities respond to changes in climate variation. Much of what we know about tree and forest response to climate vAuthorsJane R. Foster, Andrew O. Finley, Anthony W. D'Amato, John B. Bradford, Sudipto BanerjeeMid-latitude shrub steppe plant communities: Climate change consequences for soil water resources
In the coming century, climate change is projected to impact precipitation and temperature regimes worldwide, with especially large effects in drylands. We use big sagebrush ecosystems as a model dryland ecosystem to explore the impacts of altered climate on ecohydrology and the implications of those changes for big sagebrush plant communities using output from 10 Global Circulation Models (GCMs)AuthorsKyle A. Palmquist, Daniel R. Schlaepfer, John B. Bradford, Willliam K. LauenrothA review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration
The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling emergence and/or establishmentAuthorsMatthew Petrie, A.M. Wildeman, John B. Bradford, R.M. Hubbard, W.K. LauenrothDoes the stress-gradient hypothesis hold water? Disentangling spatial and temporal variation in plant effects on soil moisture in dryland systems
The nature of the relationship between water limitation and facilitation has been one of the most contentious debates surrounding the stress-gradient hypothesis (SGH), which states that plant-plant interactions shift from competition to facilitation with increasing environmental stress. We take a closer look at the potential role of soil moisture in mediating plant-plant interaction outcomes by aAuthorsBradley J. Butterfield, John B. Bradford, Cristina Armas, Ivan Prieto, Francisco I. PugnaireThe integrated rangeland fire management strategy actionable science plan
The Integrated Rangeland Fire Management Strategy (hereafter Strategy, DOI 2015) outlined the need for coordinated, science-based adaptive management to achieve long-term protection, conservation, and restoration of the sagebrush (Artemisia spp.) ecosystem. A key component of this management approach is the identification of knowledge gaps that limit implementation of effective strategies to meetAuthorsCameron L. Aldridge, Ken Berg, Chad S. Boyd, Stephen P. Boyte, John B. Bradford, Ed Brunson, John H. Cissel, Courtney J. Conway, Anna D. Chalfoun, Jeanne C. Chambers, Patrick Clark, Peter S. Coates, Michele R. Crist, Dawn M. Davis, Nicole DeCrappeo, Patricia A. Deibert, Kevin E. Doherty, Louisa B. Evers, Deborah M. Finch, Sean P. Finn, Matthew J. Germino, Nancy F. Glenn, Corey Gucker, John A. Hall, Steven E. Hanser, Douglas W. Havlina, Julie A. Heinrichs, Matt Heller, Collin G. Homer, Molly E. Hunter, Ruth W. Jacobs, Jason W. Karl, Richard Kearney, Susan K Kemp, Francis F. Kilkenny, Steven T. Knick, Karen Launchbaugh, Daniel J. Manier, Kenneth E. Mayer, Susan E. Meyer, Adrian P. Monroe, Eugénie MontBlanc, Beth A. Newingham, Michael L. Pellant, Susan L. Phillips, David S. Pilliod, Mark A. Ricca, Bryce A. Richardson, Jeffrey A. Rose, Nancy Shaw, Roger L. Sheley, Douglas J. Shinneman, Lief A. Wiechman, Bruce K. WylieGrowth-climate relationships across topographic gradients in the northern Great Lakes
Climatic conditions exert important control over the growth, productivity, and distribution of forests, and characterizing these relationships is essential for understanding how forest ecosystems will respond to climate change. We used dendrochronological methods to develop climate–growth relationships for two dominant species, Populus tremuloides (quaking aspen) and Pinus resinosa (red pine), inAuthorsS.F. Dymond, A.W. D'Amato, R.K. Kolka, P.V. Bolstad, S.D. Sebestyen, John B. BradfordLiDAR based prediction of forest biomass using hierarchical models with spatially varying coefficients
Many studies and production inventory systems have shown the utility of coupling covariates derived from Light Detection and Ranging (LiDAR) data with forest variables measured on georeferenced inventory plots through regression models. The objective of this study was to propose and assess the use of a Bayesian hierarchical modeling framework that accommodates both residual spatial dependence andAuthorsChad Babcock, Andrew O. Finley, John B. Bradford, Randall K. Kolka, Richard A. Birdsey, Michael G. RyanDesert grassland responses to climate and soil moisture suggest divergent vulnerabilities across the southwestern United States
Climate change predictions include warming and drying trends, which are expected to be particularly pronounced in the southwestern United States. In this region, grassland dynamics are tightly linked to available moisture, yet it has proven difficult to resolve what aspects of climate drive vegetation change. In part, this is because it is unclear how heterogeneity in soils affects plant responsesAuthorsJennifer Gremer, John B. Bradford, Seth M. Munson, Michael C. DuniwayScale dependence of disease impacts on quaking aspen (Populus tremuloides) mortality in the southwestern United States
Depending on how disease impacts tree exposure to risk, both the prevalence of disease and disease effects on survival may contribute to patterns of mortality risk across a species' range. Disease may accelerate tree species' declines in response to global change factors, such as drought, biotic interactions, such as competition, or functional traits, such as allometry. To assess the role of diseaAuthorsDavid M. Bell, John B. Bradford, William K. Lauenroth - Science
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