Jessica J Walker
Jessica started with the USGS as a Mendenhall Postdoctoral Researcher in 2014.
Jessica's broad research interests center on the analysis of landscape change using remote sensing data. Past projects have included tracking the vegetative trajectories of areas recovering from fire events, both in the semi-arid, high-elevation forests of Arizona and the boreal forests of Alaska. Additional recent work includes examining surface inundation patterns via Landsat and MODIS imagery as part of the PLACE project (Patterns in the Landscape - Analyses of Cause and Effect).
Education and Certifications
2012 - Ph.D. Geospatial and Environmental Analysis, Virginia Tech
2000 - M.A. Geography, University of Arizona, Tucson
1991 - B.A. Applied Math, Williams College
Science and Products
Filter Total Items: 13
Data - Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA Data - Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA
Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the central Cascade Mountain area, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous...
Filter Total Items: 19
Phenology patterns indicate recovery trajectories of ponderosa pine forests after high-severity fires Phenology patterns indicate recovery trajectories of ponderosa pine forests after high-severity fires
Post-fire recovery trajectories in ponderosa pine (Pinus ponderosa Laws.) forests of the US Southwest are increasingly shifting away from pre-burn vegetation communities. This study investigated whether phenological metrics derived from a multi-decade remotely sensed imagery time-series could differentiate among grass, evergreen shrub, deciduous, or conifer-dominated replacement pathways...
Authors
Jessica J. Walker, Christopher E. Soulard
Integrating stream gage data and Landsat imagery to complete time-series of surface water extents in Central Valley, California Integrating stream gage data and Landsat imagery to complete time-series of surface water extents in Central Valley, California
Accurate monitoring of surface water location and extent is critical for the management of diverse water resource phenomena. The multi-decadal archive of Landsat satellite imagery is punctuated by missing data due to cloud cover during acquisition times, hindering the assembly of a continuous time series of inundation dynamics. This study investigated whether streamflow volume...
Authors
Jessica J. Walker, Christopher E. Soulard, Roy E. Petrakis
Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways
Warming temperatures associated with climate change can have indirect effects on migratory birds that rely on seasonally available food resources and habitats that vary across spatial and temporal scales. We used two heat-based indices of spring onset, the First Leaf Index (FLI) and the First Bloom Index (FBI), as proxies of habitat change for the period 1901 to 2012 at three spatial...
Authors
Eric K. Waller, Theresa M. Crimmins, Jessica J. Walker, Erin E. Posthumus, Jake Weltzin
Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA
Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the Cascade Mountains, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous Change...
Authors
Christopher E. Soulard, Jessica J. Walker, Glenn E. Griffith
Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California
To assess how montane meadow vegetation recovered after a wildfire that occurred in Yosemite National Park, CA in 1996, Google Earth Engine image processing was applied to leverage the entire Landsat Thematic Mapper archive from 1985 to 2012. Vegetation greenness (normalized difference vegetation index [NDVI]) was summarized every 16 days across the 28-year Landsat time series for 26...
Authors
Christopher E. Soulard, Christine M. Albano, Miguel L. Villarreal, Jessica J. Walker
Mapping presence and predicting phenological status of invasive buffelgrass in southern Arizona using MODIS, climate and citizen science observation data Mapping presence and predicting phenological status of invasive buffelgrass in southern Arizona using MODIS, climate and citizen science observation data
The increasing spread and abundance of an invasive perennial grass, buffelgrass (Pennisetum ciliare), represents a critical threat to the native vegetation communities of the Sonoran desert in southern Arizona, USA, where buffelgrass eradication is a high priority for resource managers. Herbicidal treatment of buffelgrass is most effective when the vegetation is actively growing, but the
Authors
Cynthia S.A. Wallace, Jessica J. Walker, Susan M. Skirvin, Caroline Patrick-Birdwell, Jake F. Weltzin, Helen Raichle
Phenological response of an Arizona dryland forest to short-term climatic extremes Phenological response of an Arizona dryland forest to short-term climatic extremes
Baseline information about dryland forest phenology is necessary to accurately anticipate future ecosystem shifts. The overarching goal of our study was to investigate the variability of vegetation phenology across a dryland forest landscape in response to climate alterations. We analyzed the influence of site characteristics and climatic conditions on the phenological patterns of an...
Authors
Jessica J. Walker, Kirsten de Beurs, Randolph Wynne
Science and Products
Filter Total Items: 13
Data - Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA Data - Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA
Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the central Cascade Mountain area, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous...
Filter Total Items: 19
Phenology patterns indicate recovery trajectories of ponderosa pine forests after high-severity fires Phenology patterns indicate recovery trajectories of ponderosa pine forests after high-severity fires
Post-fire recovery trajectories in ponderosa pine (Pinus ponderosa Laws.) forests of the US Southwest are increasingly shifting away from pre-burn vegetation communities. This study investigated whether phenological metrics derived from a multi-decade remotely sensed imagery time-series could differentiate among grass, evergreen shrub, deciduous, or conifer-dominated replacement pathways...
Authors
Jessica J. Walker, Christopher E. Soulard
Integrating stream gage data and Landsat imagery to complete time-series of surface water extents in Central Valley, California Integrating stream gage data and Landsat imagery to complete time-series of surface water extents in Central Valley, California
Accurate monitoring of surface water location and extent is critical for the management of diverse water resource phenomena. The multi-decadal archive of Landsat satellite imagery is punctuated by missing data due to cloud cover during acquisition times, hindering the assembly of a continuous time series of inundation dynamics. This study investigated whether streamflow volume...
Authors
Jessica J. Walker, Christopher E. Soulard, Roy E. Petrakis
Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways
Warming temperatures associated with climate change can have indirect effects on migratory birds that rely on seasonally available food resources and habitats that vary across spatial and temporal scales. We used two heat-based indices of spring onset, the First Leaf Index (FLI) and the First Bloom Index (FBI), as proxies of habitat change for the period 1901 to 2012 at three spatial...
Authors
Eric K. Waller, Theresa M. Crimmins, Jessica J. Walker, Erin E. Posthumus, Jake Weltzin
Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA
Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the Cascade Mountains, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous Change...
Authors
Christopher E. Soulard, Jessica J. Walker, Glenn E. Griffith
Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California
To assess how montane meadow vegetation recovered after a wildfire that occurred in Yosemite National Park, CA in 1996, Google Earth Engine image processing was applied to leverage the entire Landsat Thematic Mapper archive from 1985 to 2012. Vegetation greenness (normalized difference vegetation index [NDVI]) was summarized every 16 days across the 28-year Landsat time series for 26...
Authors
Christopher E. Soulard, Christine M. Albano, Miguel L. Villarreal, Jessica J. Walker
Mapping presence and predicting phenological status of invasive buffelgrass in southern Arizona using MODIS, climate and citizen science observation data Mapping presence and predicting phenological status of invasive buffelgrass in southern Arizona using MODIS, climate and citizen science observation data
The increasing spread and abundance of an invasive perennial grass, buffelgrass (Pennisetum ciliare), represents a critical threat to the native vegetation communities of the Sonoran desert in southern Arizona, USA, where buffelgrass eradication is a high priority for resource managers. Herbicidal treatment of buffelgrass is most effective when the vegetation is actively growing, but the
Authors
Cynthia S.A. Wallace, Jessica J. Walker, Susan M. Skirvin, Caroline Patrick-Birdwell, Jake F. Weltzin, Helen Raichle
Phenological response of an Arizona dryland forest to short-term climatic extremes Phenological response of an Arizona dryland forest to short-term climatic extremes
Baseline information about dryland forest phenology is necessary to accurately anticipate future ecosystem shifts. The overarching goal of our study was to investigate the variability of vegetation phenology across a dryland forest landscape in response to climate alterations. We analyzed the influence of site characteristics and climatic conditions on the phenological patterns of an...
Authors
Jessica J. Walker, Kirsten de Beurs, Randolph Wynne