Debra A Willard, Ph.D.
I am a palynologist (pollen and spores) with expertise in paleoecology, paleoclimatology, and biostratigraphy. My biostratigraphic expertise extends from the Carboniferous to the Holocene, with an emphasis on Euramerica (Paleozoic) and the Northern Hemisphere. My paleoclimate expertise includes the late Paleozoic and the Paleogene to Holocene intervals.
Editorial Boards
- Global and Planetary Change
- Frontiers in Ecology and Evolution – Paleoecology section Review Editor
- Quaternary
- Review of Palaeobotany and Palynology
Professional Experience
2021-Present Research Geologist, US Geological Survey, Reston, Virginia
2011-2021 Coordinator, USGS Climate Research & Development Program
1991-2011 Research Geologist, US Geological Survey, Reston, Virginia
1990-1991 Postdoctoral Researcher, National Museum of Natural History, Smithsonian Institution, Washington, DC
Education and Certifications
University of Illinois at Urbana-Champaign - Ph.D., Botany 1990
University of Illinois at Urbana-Champaign - M.S., Botany 1985
The Pennsylvania State University - B.S., Botany 1982
Stephens College - A.A., Geology 1980
Affiliations and Memberships*
American Geophysical Union
Geological Society of America
The Palynological Society
Science and Products
Late Holocene vegetation, climate, and land-use impacts on carbon dynamics in the Florida Everglades
Reconstructing vegetation response to altered hydrology and its use for restoration, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida
Chronology from sediment cores collected in southwestern Everglades National Park, Florida
Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay
Climate variability during the Medieval Climate Anomaly and Little Ice Age based on ostracod faunas and shell geochemistry from Biscayne Bay, Florida
Timing and duration of North American glacial lake discharges and the Younger Dryas climate reversal
Recent and historic drivers of landscape change in the Everglades ridge, slough, and Tree Island mosaic
Development and application of a pollen-based paleohydrologic reconstruction from the lower Roanoke River Basin, North Carolina, USA
Interdisciplinary environmental project probes Chesapeake Bay down to the core
Impacts of past climate and sea level change on Everglades wetlands: placing a century of anthropogenic change into a late-Holocene context
Micropaleontologic record of Quaternary paleoenvironments in the Central Albemarle Embayment, North Carolina, U.S.A.
Millennial-scale variability during the last glacial in vegetation records from North America
Science and Products
- Science
- Data
- Multimedia
- Publications
Filter Total Items: 100
Late Holocene vegetation, climate, and land-use impacts on carbon dynamics in the Florida Everglades
Tropical and subtropical peatlands are considered a significant carbon sink. The Florida Everglades includes 6000-km2 of peat-accumulating wetland; however, detailed carbon dynamics from different environments within the Everglades have not been extensively studied or compared. Here we present carbon accumulation rates from 13 cores and 4 different environments, including sawgrass ridges and slougAuthorsMiriam C. Jones, Christopher E. Bernhardt, Debra A. WillardReconstructing vegetation response to altered hydrology and its use for restoration, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida
We present reconstructed hydrologic and vegetation trends of the last three centuries across the Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida in order to understand the effects of 20th century water management. We analyzed pollen assemblages from cores at marsh sites along three transects to document vegetation and infer hydroperiod and water depth both before and after human aAuthorsChristopher E. Bernhardt, Laura A. Brandt, Bryan D. Landacre, Marci E. Marot, Debra A. WillardChronology from sediment cores collected in southwestern Everglades National Park, Florida
Age model data are presented for 10 cores from the southwestern coastal mangrove zone of Everglades National Park, Florida, collected in Common Era (CE) 2004 and 2005 and used for paleoecological analysis. Carbon-14 (14C), lead-210 (210Pb), cesium-137 (137Cs), radium-226 (226Ra), and pollen biostratigraphic information is included, and age models were generated for 6 of the 10 cores. Age reversalsAuthorsC.E. Bernhardt, G.L. Wingard, D. A. Willard, M. E. Marot, B. Landacre, C. W. HolmesShipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay
Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite andAuthorsAnjana K. Shah, Peter R. Vogt, Joseph G. Rosenbaum, Wayne L. Newell, Thomas M. Cronin, Debra A. Willard, Rick A. Hagen, John Brozena, Albert HofstraClimate variability during the Medieval Climate Anomaly and Little Ice Age based on ostracod faunas and shell geochemistry from Biscayne Bay, Florida
An 800-year-long environmental history of Biscayne Bay, Florida, is reconstructed from ostracod faunal and shell geochemical (oxygen, carbon isotopes, Mg/Ca ratios) studies of sediment cores from three mudbanks in the central and southern parts of the bay. Using calibrations derived from analyses of modern Biscayne and Florida Bay ostracods, palaeosalinity oscillations associated with changes in pAuthorsThomas M. Cronin, G. Lynn Wingard, Gary S. Dwyer, Peter K. Swart, Debra A. Willard, Jessica AlbietzTiming and duration of North American glacial lake discharges and the Younger Dryas climate reversal
No abstract available.AuthorsJ. A. Rayburn, Thomas M. Cronin, D. A. Franzi, P. L. K. Knuepfer, Debra A. WillardRecent and historic drivers of landscape change in the Everglades ridge, slough, and Tree Island mosaic
More than half of the original Everglades extent formed a patterned peat mosaic of elevated ridges, lower and more open sloughs, and tree islands aligned parallel to the dominant flow direction. This ecologically important landscape structure remained in a dynamic equilibrium for millennia prior to rapid degradation over the past century in response to human manipulation of the hydrologic system.AuthorsLaurel G. Larsen, Nicholas Aumen, Christopher E. Bernhardt, Vic Engel, Thomas J. Givnish, P McCormick S Hagerthey, Judson Harvey, Lynn Leonard, P. McCormick, Christopher McVoy, Gregory B. Noe, Martha K. Nungesser, K. Rutchey, Fred Sklar, Tiffany G. Troxler, John C. Volin, Debra A. WillardDevelopment and application of a pollen-based paleohydrologic reconstruction from the lower Roanoke River Basin, North Carolina, USA
We used pollen assemblages to reconstruct late-Holocene paleohydrologic patterns in floodplain deposits from the lower Roanoke River basin (North Carolina, southeastern USA). Using 120 surface samples from 38 transects, we documented statistical relationships between pollen assemblages, vegetation, and landforms. Backswamp pollen assemblages (long hydroperiods) are dominated by Nyssa (tupelo) andAuthorsD. Willard, C. Bernhardt, R. Brown, B. Landacre, P. TownsendInterdisciplinary environmental project probes Chesapeake Bay down to the core
Interrelated environmental concerns about Chesapeake Bay are being addressed in an interdisciplinary project using paleoecological and geochemical records from sediment cores to investigate Holocene climate and human encroachment. The research is looking at interannual through millennial-scale variability of bay salinity, sediment accumulation, and dissolved oxygen, temperature, and faunal and floAuthorsThomas M. Cronin, S. Colman, D. Willard, R. Kerhin, C. Holmes, A. Karlsen, S. Ishman, J. BrattonImpacts of past climate and sea level change on Everglades wetlands: placing a century of anthropogenic change into a late-Holocene context
We synthesize existing evidence on the ecological history of the Florida Everglades since its inception ~7 ka (calibrated kiloannum) and evaluate the relative impacts of sea level rise, climate variability, and human alteration of Everglades hydrology on wetland plant communities. Initial freshwater peat accumulation began between 6 and 7 ka on the platform underlying modern Florida Bay when sea lAuthorsD. A. Willard, C.E. BernhardtMicropaleontologic record of Quaternary paleoenvironments in the Central Albemarle Embayment, North Carolina, U.S.A.
To understand the temporal and spatial variation of eustatic sea-level fluctuations, glacio–hydro–isostacy, tectonics, subsidence, geologic environments and sedimentation patterns for the Quaternary of a passive continental margin, a nearly complete stratigraphic record that is fully integrated with a three dimensional chronostratigraphic framework, and paleoenvironmental information are necessaryAuthorsStephen J. Culver, Kathleen M. Farrell, David J. Mallinson, Debra A. Willard, Benjamin P. Horton, Stanley R. Riggs, E. Robert Thieler, John F. Wehmiller, Peter Parham, Scott W. Snyder, Caroline HillierMillennial-scale variability during the last glacial in vegetation records from North America
High-resolution pollen records from North America show that terrestrial environments were affected by Dansgaard-Oeschger (D-O) and Heinrich climate variability during the last glacial. In the western, more mountainous regions, these climate changes are generally observed in the pollen records as altitudinal movements of climate-sensitive plant species, whereas in the southeast, they are recorded aAuthorsGonzalo Jiménez-Moreno, R. Scott Anderson, S. Desprat, L.D. Grigg, E.C. Grimm, L.E. Heusser, Brian F. Jacobs, C. Lopez-Martinez, C.L. Whitlock, D. A. Willard - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government