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
Sea level rise in Tampa Bay
Synthesis of U.S. Geological Survey science for the Chesapeake Bay ecosystem and implications for environmental management
Paleoecology of the Late Pennsylvanian-age Calhoun coal bed and implications for long-term dynamics of wetland ecosystems
Deglacial climate variability in central Florida, USA
Rapid sea level rise and ice sheet response to 8,200-year climate event
Response of Everglades tree islands to environmental change
Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida
Impact of millennial-scale Holocene climate variability on eastern North American terrestrial ecosystems: Pollen-based climatic reconstruction
Tree islands of the Florida everglades? Long-term stability and response to hydrologic change
Ecosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses - year two
Atlas of pollen and spores of the Florida Everglades
Anthropogenic and natural variation in ridge and slough pollen assemblages
Science and Products
- Science
- Data
- Multimedia
- Publications
Filter Total Items: 100
Sea level rise in Tampa Bay
Understanding relative sea level (RSL) rise during periods of rapid climatic change is critical for evaluating modern sea level rise given the vulnerability of Antarctic ice shelves to collapse [Hodgson et al, 2006], the retreat of the world's glaciers [Oerlemans, 2005], and mass balance trends of the Greenland ice sheet [Rignot and Kanagaratnam, 2006]. The first-order pattern of global sea levelAuthorsT. Cronin, N.T. Edgar, Gillian L. Brooks, D. Hastings, R. Larson, A. Hine, S. Locker, B. Suthard, B. Flower, D. Hollander, J. Wehmiller, D. Willard, S. SmithSynthesis of U.S. Geological Survey science for the Chesapeake Bay ecosystem and implications for environmental management
The purpose of this report is to present a synthesis of the USGS Chesapeake Bay science related to the 2001-06 goals and provide implications for environmental management. The report provides USGS findings that address the science needs of the Chesapeake Bay Program (CBP) restoration goals and includes summaries of 1. land-use change; 2. water quality in the watershed, including nutrients, sedimenAuthorsScott W. Ator, Vicki S. Blazer, John W. Brakebill, Donald R. Cahoon, Peter R. Claggett, Thomas M. Cronin, Judith M. Denver, Christine L. Densmore, Allen C. Gellis, Cliff R. Hupp, Jurate M. Landwehr, Michael J. Langland, Christopher A. Ottinger, Milan J. Pavich, Matthew C. Perry, Scott W. Phillips, Stephen D. Preston, Jeff P. Raffensperger, Barnett A. Rattner, Nancy B. Rybicki, Debra A. WillardPaleoecology of the Late Pennsylvanian-age Calhoun coal bed and implications for long-term dynamics of wetland ecosystems
Quantitative plant assemblage data from coal balls, miospores, megaspores, and compression floras from the Calhoun coal bed (Missourian) of the Illinois Basin (USA) are used to interpret spatial and temporal changes in plant communities in the paleo-peat swamp. Coal-ball and miospore floras from the Calhoun coal bed are dominated strongly by tree ferns, and pteridosperms and sigillarian lycopsidsAuthorsD. A. Willard, T.L. Phillips, Alicia D. Lesnikowska, William A. DiMicheleDeglacial climate variability in central Florida, USA
Pollen and ostracode evidence from lacustrine sediments underlying modern Tampa Bay, Florida, document frequent and abrupt climatic and hydrological events superimposed on deglacial warming in the subtropics. Radiocarbon chronology on well-preserved mollusk shells and pollen residue from core MD02-2579 documents continuous sedimentation in a variety of non-marine habitats in a karst-controlled basAuthorsD. A. Willard, C.E. Bernhardt, G. R. Brooks, T. M. Cronin, T. Edgar, R. LarsonRapid sea level rise and ice sheet response to 8,200-year climate event
The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6–8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sea level rise during this event.AuthorsT. M. Cronin, P.R. Vogt, D. A. Willard, R. Thunell, J. Halka, M. Berke, J. PohlmanResponse of Everglades tree islands to environmental change
Tree islands are centers of biodiversity within the Florida Everglades, USA, but the factors controlling their distribution, formation, and development are poorly understood. We use pollen assemblages from tree islands throughout the greater Everglades ecosystem to reconstruct the timing of tree island formation, patterns of development, and response to specific climatic and environmental stressorAuthorsDebra A. Willard, Christopher E. Bernhardt, Charles W. Holmes, Bryan Landacre, Marci E. MarotDescriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida
Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measAuthorsG. Lynn Wingard, Thomas M. Cronin, Charles W. Holmes, Debra A. Willard, Carlos A. Budet, Ruth E. OrtizImpact of millennial-scale Holocene climate variability on eastern North American terrestrial ecosystems: Pollen-based climatic reconstruction
We present paleoclimatic evidence for a series of Holocene millennial-scale cool intervals in eastern North America that occurred every ???1400 years and lasted ???300-500 years, based on pollen data from Chesapeake Bay in the mid-Atlantic region of the United States. The cool events are indicated by significant decreases in pine pollen, which we interpret as representing decreases in January tempAuthorsD. A. Willard, C.E. Bernhardt, D.A. Korejwo, S.R. MeyersTree islands of the Florida everglades? Long-term stability and response to hydrologic change
Tree islands are important centers of biodiversity in the Florida Everglades; they have two to three times the plant and animal diversity of the surrounding wetlands. This high diversity is due primarily to their higher elevation relative to the adjacent wetlands (fig. 1). In the natural Everglades system, water levels fluctuated seasonally with rainfall, and tree islands were the only sites thatAuthorsDebra A. WillardEcosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses - year two
The Comprehensive Everglades Restoration Plan (CERP) lists restoration of the timing, quantity, and quality of the natural flow of freshwater as one its primary goals. Before restoration can occur, however, the baseline conditions of the environment prior to significant human alteration must be established and the range of variation within the natural system must be determined. In addition, theAuthorsG. Lynn Wingard, Thomas M. Cronin, Charles W. Holmes, Debra A. Willard, Gary S. Dwyer, Scott E. Ishman, William Orem, Christopher P. Williams, Jessica Albietz, Christopher E. Bernhardt, Carlos A. Budet, Bryan Landacre, Terry Lerch, Marci Marot, Ruth E. OrtizAtlas of pollen and spores of the Florida Everglades
An illustrated, descriptive atlas of pollen and spores from wetland plants of the Florida Everglades was compiled to facilitate identification of dispersed palynomorphs in sediments. The atlas includes 121 wetland species characteristic of eleven plant associations of the Florida Everglades including sloughs, sawgrass marshes, tree islands, wet prairies, cypress domes, mangrove forests, salt marshAuthorsDebra A. Willard, Christopher E. Bernhardt, Lisa M. Weimer, S. R. Cooper, Desire Gamez, Jennifer JensenAnthropogenic and natural variation in ridge and slough pollen assemblages
No abstract available.AuthorsC.E. Bernhardt, D. A. Willard, M. Marot, C. W. Holmes - 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