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
Millennial-scale variability during the last glacial in vegetation records from North America
Response of the everglades ridge and slough landscape to climate variability and 20th-century water management
A Holocene record of climate-driven shifts in coastal carbon sequestration
Mid-Cenozoic tectonic and paleoenvironmental setting of the central Arctic Ocean
Increased terrestrial to ocean sediment and carbon fluxes in the northern Chesapeake Bay associated with twentieth century land alteration
A 26 million year gap in the central Arctic record at the greenhouse-icehouse transition: Looking for clues
Impacts of post-glacial lake drainage events and revised chronology of the Champlain Sea episode 13-9 ka
Micropaleontologic record of late Pliocene and Quaternary paleoenvironments in the northern Albemarle Embayment, North Carolina, U.S.A.
Paleoecology and ecosystem restoration: Case studies from Chesapeake Bay and the Florida Everglades
Marl Prairie Vegetation Response to 20th Century Hydrologic Change
Synthesis of age data and chronology for Florida Bay and Biscayne Bay cores collected for ecosystem history of South Florida’s estuaries project
USGS Tampa Bay Pilot Study
Science and Products
- Science
- Data
- Multimedia
- Publications
Filter Total Items: 100
Millennial-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. WillardResponse of the everglades ridge and slough landscape to climate variability and 20th-century water management
The ridge and slough landscape of the Florida Everglades consists of a mosaic of linear sawgrass ridges separated by deeper-water sloughs with tree islands interspersed throughout the landscape. We used pollen assemblages from transects of sediment cores spanning sawgrass ridges, sloughs, and ridge-slough transition zones to determine the timing of ridge and slough formation and to evaluate the reAuthorsC.E. Bernhardt, D. A. WillardA Holocene record of climate-driven shifts in coastal carbon sequestration
A sediment core collected in the mesohaline portion of Chesapeake Bay was found to contain periods of increased delivery of refractory black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs). The BC was most likely produced by biomass combustion during four centennialscale dry periods as indicated by the Palmer Drought Severity Index (PDSI), beginning in the late Medieval Warm Period of 1100AuthorsSiddhartha Mitra, A.R. Zimmerman, G.B. Hunsinger, D. Willard, J.C. DunnMid-Cenozoic tectonic and paleoenvironmental setting of the central Arctic Ocean
Drilling results from the Integrated Ocean Drilling Program's Arctic Coring Expedition (ACEX) to the Lomonosov Ridge (LR) document a 26 million year hiatus that separates freshwater-influenced biosilica-rich deposits of the middle Eocene from fossil-poor glaciomarine silty clays of the early Miocene. Detailed micropaleontological and sedimentological data from sediments surrounding this mid-CenozoAuthorsM. O'Regan, K. Moran, J. Backman, M. Jakobsson, F. Sangiorgi, Henk Brinkhuis, Rob Pockalny, Alasdair Skelton, Catherine E. Stickley, N. Koc, Hans-Juergen Brumsack, Debra A. WillardIncreased terrestrial to ocean sediment and carbon fluxes in the northern Chesapeake Bay associated with twentieth century land alteration
We calculated Chesapeake Bay (CB) sediment and carbon fluxes before and after major anthropogenic land clearance using robust monitoring, modeling and sedimentary data. Four distinct fluxes in the estuarine system were considered including (1) the flux of eroded material from the watershed to streams, (2) the flux of suspended sediment at river fall lines, (3) the burial flux in tributary sedimentAuthorsC. Saenger, T. M. Cronin, D. Willard, J. Halka, R. KerhinA 26 million year gap in the central Arctic record at the greenhouse-icehouse transition: Looking for clues
The Cenozoic record of the Lomonosov Ridge (central Arctic Ocean) recovered during Integrated Ocean Drilling Program (IODP) Expedition 302 revealed an unexpected 26 Ma hiatus, separating middle Eocene (∼44.4 Ma) from lower Miocene sediments (∼18.2 Ma). To elucidate the nature of this unconformity, we performed a multiproxy palynological (dinoflagellate cysts, pollen, and spores), micropaleontologiAuthorsFrancesca Sangiorgi, Hans-Juergen Brumsack, Debra A. Willard, Stefan Schouten, Catherine E. Stickley, Matthew O'Regan, Gert-Jan Reichart, Jaap S. Sinninghe Damste, Henk BrinkhuisImpacts of post-glacial lake drainage events and revised chronology of the Champlain Sea episode 13-9 ka
Lithologic, CHIRP (Compressed High Intensity Radar Pulse) sonar, paleomagnetic, stable isotopic and micropaleontological analyses of sediment cores from Lake Champlain (New York, Vermont) were used to determine the age of the post-glacial Champlain Sea marine episode, the timing of salinity changes and their relationship to freshwater discharge from mid-continent glacial lakes. Calibrated radiocarAuthorsT. M. Cronin, P.L. Manley, S. Brachfeld, T.O. Manley, D. A. Willard, J.-P. Guilbault, J.A. Rayburn, R. Thunell, M. BerkeMicropaleontologic record of late Pliocene and Quaternary paleoenvironments in the northern Albemarle Embayment, North Carolina, U.S.A.
Micropaleontological data provide a strong actualistic basis for detailed interpretations of Quaternary paleoenvironmental change. The 90 m-thick Quaternary record of the Albemarle Embayment in the mid-Atlantic coastal plain of the USA provides an excellent opportunity to use such an approach in a region where the details of Quaternary environmental change are poorly known.The foraminiferal recordAuthorsS.J. Culver, K.M. Farrell, D. J. Mallinson, B. P. Horton, D. A. Willard, E. R. Thieler, S.R. Riggs, S.W. Snyder, J.F. Wehmiller, C.E. Bernhardt, C. HillierPaleoecology and ecosystem restoration: Case studies from Chesapeake Bay and the Florida Everglades
Climate extremes that cause droughts, floods, or large temperature fluctuations can complicate ecosystem restoration efforts focused on local and regional human disturbance. Restoration targets are often based primarily on monitoring data and modeling simulations, which provide information on species' short-term response to disturbance and environmental variables. Consequently, the targets may beAuthorsDebra A. Willard, Thomas M. CroninMarl Prairie Vegetation Response to 20th Century Hydrologic Change
We conducted geochronologic and pollen analyses from sediment cores collected in solution holes within marl prairies of Big Cypress National Preserve to reconstruct vegetation patterns of the last few centuries and evaluate the stability and longevity of marl prairies within the greater Everglades ecosystem. Based on radiocarbon dating and pollen biostratigraphy, these cores contain sediments depoAuthorsChristopher E. Bernhardt, Debra A. WillardSynthesis of age data and chronology for Florida Bay and Biscayne Bay cores collected for ecosystem history of South Florida’s estuaries project
210Pb, 14C, and pollen biostratigraphic data have been compiled and synthesized to develop age models for cores collected from Florida Bay and Biscayne Bay. These cores are being used to interpret the ecosystem history of south Florida’s estuaries by examining the physical, chemical, and biological record preserved within the cores. The beginning of the 20th century, which marks an important turniAuthorsG. Lynn Wingard, J.W. Hudley, C. W. Holmes, Debra A. Willard, M. MarotUSGS Tampa Bay Pilot Study
Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the TampAuthorsK. K. Yates, T. M. Cronin, M. Crane, M. Hansen, A. Nayeghandi, P. Swarzenski, T. Edgar, G. R. Brooks, B. Suthard, A. Hine, S. Locker, D. A. Willard, D. Hastings, B. Flower, D. Hollander, R.A. Larson, K. Smith - 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