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
The impact of anthropogenic land-cover change on the Florida Peninsula Sea Breezes and warm season sensible weather
Late-Holocene climate andecosystem history from Chesapeake Bay sediment cores, USA
Medieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay
Ecosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses
Tree Islands of the Florida Everglades - A Disappearing Resource
Paleoecological insights on fixed tree island development in the Florida Everglades: I. environmental controls
The U.S. Geological Survey and the Chesapeake Bay – The role of science in environmental restoration
Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay
The Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia
Long-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana
Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf
Pollen assemblages as paleoenvironmental proxies in the Florida Everglades
Science and Products
- Science
- Data
- Multimedia
- Publications
Filter Total Items: 100
The impact of anthropogenic land-cover change on the Florida Peninsula Sea Breezes and warm season sensible weather
During the twentieth century, the natural landscape of the Florida peninsula was transformed extensively by agriculture, urbanization, and the diversion of surface water features. The purpose of this paper is to present a numerical modeling study in which the possible impacts of this transformation on the warm season climate of the region were investigated. For three separate July–August periods (AuthorsC. H. Marshall, R.A. Pielke, L. T. Steyaert, D. A. WillardLate-Holocene climate andecosystem history from Chesapeake Bay sediment cores, USA
Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during the last 230AuthorsD. A. Willard, T. M. Cronin, S. VerardoMedieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay
We present paleoclimate evidence for rapid (< 100 years) shifts of ~2-4oC in Chesapeake Bay (CB) temperature ~2100, 1600, 950, 650, 400 and 150 years before present (years BP) reconstructed from magnesium/calcium (Mg/Ca) paleothermometry. These include large temperature excursions during the Little Ice Age (~1400-1900 AD) and the Medieval Warm Period (~800-1300 AD) possibly related to changes in tAuthorsT. M. Cronin, G. S. Dwyer, T. Kamiya, S. Schwede, D. A. WillardEcosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses
During the last century, the environs of Biscayne Bay have been greatly affected by anthropogenic alteration through urbanization of the Miami/Dade County area. The sources, timing, delivery, and quality of freshwater flow into the Bay have been changed by construction of a complex canal system that controls movement of water throughout south Florida. Changes in shoreline and sub-aquatic vegetatioAuthorsG. Lynn Wingard, Thomas M. Cronin, G. S. Dwyer, S. E. Ishman, D. A. Willard, C. W. Holmes, C.E. Bernhardt, C.P. Williams, M. E. Marot, J.B. Murray, R.G. Stamm, J.H. Murray, C. BudetTree Islands of the Florida Everglades - A Disappearing Resource
Until recently, the timing and cause of tree island formation have been poorly understood, with estimates of initial tree-island development as early as thousands of years ago to as recently as the last few decades. To increase our knowledge about the origins of these features, sediment cores were collected on and around tree islands. These cores were dated using radioisotopic techniques, includinAuthorsPaleoecological insights on fixed tree island development in the Florida Everglades: I. environmental controls
Palynological and geochemical analyses of sediment cores collected on two tree islands in the Florida Everglades indicate long-term hydrologic and chemical differences between tree islands and surrounding marshes and sloughs. Gumbo Limbo and Nuthouse tree islands are elongate, teardrop-shaped islands in Water Conservation Area 3B. Prior to tree island formation at both sites, pollen records indicaAuthorsDebra A. Willard, James B. Murray, Charles W. Holmes, Michael S. Korvela, Daniel Mason, William H. Orem, D. Timothy TowlesThe U.S. Geological Survey and the Chesapeake Bay – The role of science in environmental restoration
The Chesapeake Bay is the Nation's largest estuary and historically supported one of the most productive fisheries in the world. In addition to supporting aquatic communities and wildlife, the bay's watershed serves the economic and recreational needs of 15 million people. The fertile soils of the watershed support significant agricultural production. Unfortunately, the commercial, economic, and rAuthorsRoger A. Barlow, John W. Brakebill, John F. Bratton, Vicki S. Blazer, John Karl Bohlke, Owen P. Bricker, Steve M. Colman, Thomas M. Cronin, Cliff R. Hupp, Janet R. Keough, Jurate M. Landwehr, Michael J. Langland, Wayne L. Newell, Matthew Perry, Scott W. Phillips, Steve D. Preston, Nancy B. Rybicki, Nancy S. Simon, Debra A. WillardByEcosystems Mission Area, Water Resources Mission Area, Climate Adaptation Science Centers, Chesapeake Bay Activities, Eastern Ecological Science Center, Florence Bascom Geoscience Center, Maryland-Delaware-D.C. Water Science Center, Pennsylvania Water Science Center, Woods Hole Coastal and Marine Science CenterRadiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay
Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materialAuthorsSteven M. Colman, P.C. Baucom, J.F. Bratton, T. M. Cronin, J. P. McGeehin, D. Willard, A.R. Zimmerman, P.R. VogtThe Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia
No abstract available.AuthorsDebra A. Willard, Charles W. Holmes, Lisa M. WeimerLong-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana
No abstract available.AuthorsD. A. Willard, T. M. Cronin, S. E. Ishman, Marci MarotBedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf
Two piston cores from the Eurasian flank of Lomonosov Ridge near lat 88.9°N, long 140°E provide the first samples of bedrock from this high-standing trans-Arctic ridge. Core 94-PC27 sampled nonmarine siltstone similar in facies and age to uppermost Triassic to lower Lower Jurassic and mid– Lower Cretaceous beds in the 4 to > 5 km Mesozoic section on Franz Josef Land, on the outer Barents shelf. AAuthorsArthur Grantz, Victoria L. Pease, Debra A. Willard, R. L. Phillips, David L. ClarkPollen assemblages as paleoenvironmental proxies in the Florida Everglades
Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet prairies, brackish marshes,AuthorsD. A. Willard, L. M. Weimer, W.L. Riegel - 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