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
Rapid inundation of the southern Florida coastline despite low relative sea-level rise rates during the late-Holocene
Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events
The mighty Susquehanna—extreme floods in Eastern North America during the past two millennia
Geographic attribution of soils using probabilistic modeling of GIS data for forensic search efforts
A North American Hydroclimate Synthesis (NAHS) of the Common Era
The ACER pollen and charcoal database: A global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
Shallow marine response to global climate change during the Paleocene-Eocene Thermal Maximum, Salisbury Embayment, USA
Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics
Holocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Coastal and wetland ecosystems of the Chesapeake Bay watershed: Applying palynology to understand impacts of changing climate, sea level, and land use
Patterns of floodplain sediment deposition along the regulated lower Roanoke River, North Carolina: annual, decadal, centennial scales
Pollen and spores of terrestrial plants
Science and Products
- Science
- Data
- Multimedia
- Publications
Filter Total Items: 100
Rapid inundation of the southern Florida coastline despite low relative sea-level rise rates during the late-Holocene
Sediment cores from Florida Bay, Everglades National Park were examined to determine ecosystem response to relative sea-level rise (RSLR) over the Holocene. High-resolution multiproxy analysis from four sites show freshwater wetlands transitioned to mangrove environments 4–3.6 ka, followed by estuarine environments 3.4–2.8 ka, during a period of enhanced climate variability. We calculate a RSLR raAuthorsMiriam Jones, G. Lynn Wingard, Bethany Stackhouse, Katherine Keller, Debra A. Willard, Marci E. Marot, Bryan D. Landacre, Christopher E. BernhardtArctic vegetation, temperature, and hydrology during Early Eocene transient global warming events
Early Eocene global climate was warmer than much of the Cenozoic and was punctuated by a series of transient warming events or ‘hyperthermals’ associated with carbon isotope excursions when temperature increased by 4–8° C. The Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) and Eocene Thermal Maximum 2 (ETM2, 53.5 Ma) hyperthermals were of short duration (< 200 kyr) and dramatically restructured tAuthorsDebra A. Willard, Timme H Donders, Tammo Reichgelt, David R Greenwood, Francien Peterse, Francesca Sangiorgi, Appy Sluijs, Stefan SchoutenThe mighty Susquehanna—extreme floods in Eastern North America during the past two millennia
The hazards posed by infrequent major floods to communities along the Susquehanna River and the ecological health of Chesapeake Bay remain largely unconstrained due to the short length of streamgage records. Here we develop a history of high‐flow events on the Susquehanna River during the late Holocene from flood deposits contained in MD99‐2209, a sediment core recovered in 26 m of water from ChesAuthorsMichael Toomey, Meagan Cantwell, Steven Colman, Thomas M. Cronin, Jeffrey P. Donnelly, Liviu Giosan, Clifford Heil, Robert L. Korty, Marci E. Marot, Debra A. WillardGeographic attribution of soils using probabilistic modeling of GIS data for forensic search efforts
Examinations of soil traces associated with forensic evidence can be used to narrow potential source area(s) by characterizing features of the trace soil assemblage, some of which are limited to specific regions. Soil characteristics may be used to infer the likelihoods of the soil trace being derived from distinct areas within digital maps, including both maps of discrete classes such as formatioAuthorsLibby A Stern, Jodi B Webb, Debra A. Willard, Christopher E. Bernhardt, David Korejwo, Maureen Bottrell, Garrett McMahon, nancy McMillan, Jared Schuetter, Patrick Wheatley, Jack HieptasA North American Hydroclimate Synthesis (NAHS) of the Common Era
This study presents a synthesis of century-scale hydroclimate variations in North America for the Common Era (last 2000 years) using new age models of previously published multiple proxy-based paleoclimate data. This North American Hydroclimate Synthesis (NAHS) examines regional hydroclimate patterns and related environmental indicators, including vegetation, lake water elevation, stream flow andAuthorsJessica R. Rodysill, Lesleigh Anderson, Thomas M. Cronin, Miriam C. Jones, Robert S. Thompson, David B. Wahl, Debra A. Willard, Jason A. Addison, Jay R. Alder, Katherine H. Anderson, Lysanna Anderson, John A. Barron, Christopher E. Bernhardt, Steven W. Hostetler, Natalie M. Kehrwald, Nicole Khan, Julie N. Richey, Scott W. Starratt, Laura E. Strickland, Michael Toomey, Claire C. Treat, G. Lynn WingardByWater Resources Mission Area, Climate Research and Development Program, Energy Resources Program, Groundwater and Streamflow Information Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Florence Bascom Geoscience Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, St. Petersburg Coastal and Marine Science CenterThe ACER pollen and charcoal database: A global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficientAuthorsM.F. Sánchez-Goñi, S. Desprat, A.-L. Daniau, F. Bassinot, J.M. Polanco-Martinez, S.P. Harrison, J.R.M. Allen, R.S. Anderson, H. Behling, R. Bonnefille, F. Burjachs, J.S. Carrión, R. Cheddadi, J.S. Clark, N. Combourieu-Nebout, C.J. Courtney Mustaphi, G.H. Debusk, L. Dupont, J. Finch, W.J. Fletcher, M. Giardini, C. González, W.D. Gosling, L.D. Grigg, E.C. Grimm, R. Hayashi, K. Helmens, Heusser. L.E., T. Hill, G. Hope, B. Huntley, Y. Igarashi, T. Irino, B. F. Jacobs, G. Jiménez-Moreno, S. Kawai, P. Kershaw, F. Kumon, I. Lawson, M.-P. Ledru, A.-M. Lézine, P.-M. Liew, D. Magri, R. Marchant, V. Margari, F. Mayle, M. McKenzie, P. Moss, U.C. Müller, F. Naughton, R.M. Newnham, T. Oba, R. Pérez-Obiol, R. Pini, C. Ravazzi, K.H. Roucoux, S. Rucina, L. Scott, H. Takahara, P.C. Tzedakis, D.H. Urrego, Debra A. Willard, B. Van Geel, B.G. Valencia, M.J. Vandergoes, A. Vincens, C.L. Whitlock, Debra A. Willard, M. YamamotoShallow marine response to global climate change during the Paleocene-Eocene Thermal Maximum, Salisbury Embayment, USA
The Paleocene-Eocene Thermal Maximum (PETM) was an interval of extreme warmth that caused disruption of marine and terrestrial ecosystems on a global scale. Here we examine the sediments, flora, and fauna from an expanded section at Mattawoman Creek-Billingsley Road (MCBR) in Maryland and explore the impact of warming at a nearshore shallow marine (30–100 m water depth) site in the Salisbury EmbayAuthorsJean Self-Trail, Marci M. Robinson, Timothy J. Bralower, Jocelyn A. Sessa, Elizabeth A. Hajek, Lee R. Kump, Sheila M. Trampush, Debra A. Willard, Lucy E. Edwards, David S. Powars, Gregory A. WandlessTrans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics
This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic divAuthorsP.A. Baker, S.C. Fritz, C.G. Silva, C.A. Rigsby, M.L. Absy, R.P. Almeida, Maria C. Caputo, C.M. Chiessi, F.W. Cruz, C.W. Dick, S.J. Feakins, J. Figueiredo, K.H. Freeman, C. Hoorn, C.A. Jaramillo, A. Kern, E.M. Latrubesse, M.P. Ledru, A. Marzoli, A. Myrbo, A. Noren, W.E. Piller, M.I.F. Ramos, C.C. Ribas, R. Trinadade, A.J. West, I. Wahnfried, Debra A. WillardHolocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Multi-proxy analyses were conducted on a sediment core from Favre Lake, a high elevation cirque lake in the northern Ruby Mountains, Nevada, and provide a ca. 7600 year record of local and regional environmental change. Data indicate that lake levels were lower from 7600-5750 cal yr BP, when local climate was warmer and/or drier than today. Effective moisture increased after 5750 cal yr BP and remAuthorsDavid B. Wahl, Scott W. Starratt, Lysanna Anderson, Jennifer E. Kusler, Christopher C. Fuller, Jason A. Addison, Elmira WanCoastal and wetland ecosystems of the Chesapeake Bay watershed: Applying palynology to understand impacts of changing climate, sea level, and land use
The mid-Atlantic region and Chesapeake Bay watershed have been influenced by fluctuations in climate and sea level since the Cretaceous, and human alteration of the landscape began ~12,000 years ago, with greatest impacts since colonial times. Efforts to devise sustainable management strategies that maximize ecosystem services are integrating data from a range of scientific disciplines to understaAuthorsDebra A. Willard, Christopher E. Bernhardt, Cliff R. Hupp, Wayne L. NewellPatterns of floodplain sediment deposition along the regulated lower Roanoke River, North Carolina: annual, decadal, centennial scales
The lower Roanoke River on the Coastal Plain of North Carolina is not embayed and maintains a floodplain that is among the largest on the mid-Atlantic Coast. This floodplain has been impacted by substantial aggradation in response to upstream colonial and post-colonial agriculture between the mid-eighteenth and mid-nineteenth centuries. Additionally, since the mid-twentieth century stream flow hasAuthorsCliff R. Hupp, Edward R. Schenk, Daniel Kroes, Debra A. Willard, Phil A. Townsend, Robert K. PeetPollen and spores of terrestrial plants
Pollen and spores are valuable tools in reconstructing past sea level and climate because of their ubiquity, abundance, and durability as well as their reciprocity with source vegetation to environmental change (Cronin, 1999; Traverse, 2007; Willard and Bernhardt, 2011). Pollan is found in many sedimentary environments, from freshwater to saltwater, terrestrial to marine. It can be abundant in a mAuthorsChristopher E. Bernhardt, Debra 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