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
Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data
Simulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts
Shifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance
Ecohydrology of dry regions: storage versus pulse soil water dynamics
Technical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States
Temperature drives global patterns in forest biomass distribution in leaves, stems, and roots
Forest Ecosystem respiration estimated from eddy covariance and chamber measurements under high turbulence and substantial tree mortality from bark beetles
Initial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region
Forest stand structure, productivity, and age mediate climatic effects on aspen decline
Natural regeneration processes in big sagebrush (Artemisia tridentata)
Modeling regeneration responses of big sagebrush (Artemisia tridentata) to abiotic conditions
Fifteen-year patterns of soil carbon and nitrogen following biomass harvesting
Science and Products
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Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data
Modern operational forest inventory often uses remotely sensed data that cover the whole inventory area to produce spatially explicit estimates of forest properties through statistical models. The data obtained by airborne light detection and ranging (LiDAR) correlate well with many forest inventory variables, such as the tree height, the timber volume, and the biomass. To construct an accurate moAuthorsVirpi Junttila, Tuomo Kauranne, Andrew O. Finley, John B. BradfordSimulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts
Many semi-arid plant communities in western North America are dominated by big sagebrush. These ecosystems are being reduced in extent and quality due to economic development, invasive species, and climate change. These pervasive modifications have generated concern about the long-term viability of sagebrush habitat and sagebrush-obligate wildlife species (notably greater sage-grouse), highlightinAuthorsDaniel R. Schlaepfer, Kyle A. Taylor, Victoria E. Pennington, Kellen N. Nelson, Trace E. Martin, Caitlin M. Rottler, William K. Lauenroth, John B. BradfordShifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance
Summary 1. Terrestrial vegetation influences hydrologic cycling. In water-limited, dryland ecosystems, altered ecohydrology as a consequence of vegetation change can impact vegetation structure, ecological functioning and ecosystem services. Shrub steppe ecosystems dominated by big sagebrush (Artemisia tridentata) are widespread across western North America, and provide a range of ecosystem servicAuthorsJohn B. Bradford, Daniel R. Schlaepfer, William K. Lauenroth, Ingrid C. BurkeEcohydrology of dry regions: storage versus pulse soil water dynamics
Although arid and semiarid regions are defined by low precipitation, the seasonal timing of temperature and precipitation can influence net primary production and plant functional type composition. The importance of precipitation seasonality is evident in semiarid areas of the western U.S., which comprise the Intermountain (IM) zone, a region that receives important winter precipitation and is domAuthorsWilliam K. Lauenroth, Daniel R. Schlaepfer, John B. BradfordTechnical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States
Forest ecosystems play a critical role in mitigating greenhouse gas emissions. Forest carbon (C) is stored through photosynthesis and released via decomposition and combustion. Relative to C fixation in biomass, much less is known about C depletion through decomposition of woody debris, particularly under a changing climate. It is assumed that the increased temperatures and longer growing seasonsAuthorsMatthew B. Russell, Christopher W. Woodall, Anthony W. D'Amato, Shawn Fraver, John B. BradfordTemperature drives global patterns in forest biomass distribution in leaves, stems, and roots
Whether the fraction of total forest biomass distributed in roots, stems, or leaves varies systematically across geographic gradients remains unknown despite its importance for understanding forest ecology and modeling global carbon cycles. It has been hypothesized that plants should maintain proportionally more biomass in the organ that acquires the most limiting resource. Accordingly, we hypotheAuthorsPeter B. Reich, Yunjian Lou, John B. Bradford, Hendrik Poorter, Charles H. Perry, Jacek OleksynForest Ecosystem respiration estimated from eddy covariance and chamber measurements under high turbulence and substantial tree mortality from bark beetles
Eddy covariance nighttime fluxes are uncertain due to potential measurement biases. Many studies report eddy covariance nighttime flux lower than flux from extrapolated chamber measurements, despite corrections for low turbulence. We compared eddy covariance and chamber estimates of ecosystem respiration at the GLEES Ameriflux site over seven growing seasons under high turbulence (summer night meaAuthorsHeather N. Speckman, John M. Frank, John B. Bradford, Brianna L. Miles, William J. Massman, William J. Parton, Michael G. RyanInitial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region
Contemporary forest management practices are increasingly designed to optimize novel objectives, such as maximizing biomass feedstocks and/or maintaining ecological legacies, but many uncertainties exist regarding how these practices influence forest carbon (C) cycling. We examined the responses of soil respiration (Rs) to biomass harvesting and green-tree retention in an effort to empirically assAuthorsValerie J. Kurth, John B. Bradford, Robert A. Slesak, Anthony W. D'AmatoForest stand structure, productivity, and age mediate climatic effects on aspen decline
Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index tAuthorsDavid M. Bell, John B. Bradford, William K. LauenrothNatural regeneration processes in big sagebrush (Artemisia tridentata)
Big sagebrush, Artemisia tridentata Nuttall (Asteraceae), is the dominant plant species of large portions of semiarid western North America. However, much of historical big sagebrush vegetation has been removed or modified. Thus, regeneration is recognized as an important component for land management. Limited knowledge about key regeneration processes, however, represents an obstacle to identifyiAuthorsDaniel R. Schlaepfer, William K. Lauenroth, John B. BradfordModeling regeneration responses of big sagebrush (Artemisia tridentata) to abiotic conditions
Ecosystems dominated by big sagebrush, Artemisia tridentata Nuttall (Asteraceae), which are the most widespread ecosystems in semiarid western North America, have been affected by land use practices and invasive species. Loss of big sagebrush and the decline of associated species, such as greater sage-grouse, are a concern to land managers and conservationists. However, big sagebrush regenerationAuthorsDaniel R. Schlaepfer, William K. Lauenroth, John B. BradfordFifteen-year patterns of soil carbon and nitrogen following biomass harvesting
The substitution of forest-derived woody biofuels for fossil fuel energy has garnered increasing attention in recent years, but information regarding the mid- and long-term effects on soil productivity is limited. We investigated 15-yr temporal trends in forest floor and mineral soil (0–30 cm) C and N pools in response to organic matter removal treatments (OMR; stem-only harvest, SOH; whole-tree hAuthorsValerie J. Kurth, Anthony W. D'Amato, Brian J. Palik, John B. Bradford - Science
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