Debra A Willard, Ph.D.
I am a palynologist (pollen and spores) with expertise in paleoecology and biostratigraphy. My biostratigraphic expertise extends from the Carboniferous to the Holocene, with an emphasis on Euramerica (Paleozoic) and the Northern Hemisphere. My paleoecological 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 Land Change Science 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
Filter Total Items: 105
A 26 million year gap in the central Arctic record at the greenhouse-icehouse transition: Looking for clues A 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)
Authors
Francesca Sangiorgi, Hans-Juergen Brumsack, Debra A. Willard, Stefan Schouten, Catherine E. Stickley, Matthew O’Regan, Gert-Jan Reichart, Jaap S. Sinninghe Damste, Henk Brinkhuis
Paleoecology and ecosystem restoration: Case studies from Chesapeake Bay and the Florida Everglades Paleoecology 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...
Authors
Debra A. Willard, Thomas M. Cronin
Marl prairie vegetation response to 20th century hydrologic change Marl 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...
Authors
Christopher E. Bernhardt, Debra A. Willard
Synthesis of age data and chronology for Florida Bay and Biscayne Bay cores collected for ecosystem history of South Florida’s estuaries project Synthesis 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...
Authors
G. Lynn Wingard, J.W. Hudley, C. W. Holmes, Debra A. Willard, M. Marot
USGS Tampa Bay Pilot Study USGS 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...
Authors
K. K. Yates, T. M. Cronin, M. Crane, M. Hansen, A. Nayeghandi, P. Swarzenski, T. Edgar, G. R. Brooks, B. Suthard, A. Hine, S. Locker, Debra A. Willard, D. Hastings, B. Flower, D. Hollander, R.A. Larson, K. Smith
Deglacial climate variability in central Florida, USA Deglacial 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...
Authors
Debra A. Willard, C.E. Bernhardt, G. R. Brooks, T. M. Cronin, T. Edgar, R. Larson
Synthesis of U.S. Geological Survey science for the Chesapeake Bay ecosystem and implications for environmental management Synthesis 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...
Authors
Scott 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. Willard
Rapid sea level rise and ice sheet response to 8,200-year climate event Rapid 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...
Authors
T. M. Cronin, P.R. Vogt, Debra A. Willard, R. Thunell, J. Halka, M. Berke, J. Pohlman
Sea level rise in Tampa Bay 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...
Authors
T. 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. Smith
Paleoecology of the Late Pennsylvanian-age Calhoun coal bed and implications for long-term dynamics of wetland ecosystems Paleoecology 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...
Authors
Debra A. Willard, T.L. Phillips, Alicia D. Lesnikowska, William A. DiMichele
Response of Everglades tree islands to environmental change Response 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...
Authors
Debra A. Willard, Christopher E. Bernhardt, Charles W. Holmes, Bryan Landacre, Marci E. Marot
Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida Descriptions 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...
Authors
G. Lynn Wingard, Thomas M. Cronin, Charles W. Holmes, Debra A. Willard, Carlos A. Budet, Ruth E. Ortiz
Science and Products
Filter Total Items: 105
A 26 million year gap in the central Arctic record at the greenhouse-icehouse transition: Looking for clues A 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)
Authors
Francesca Sangiorgi, Hans-Juergen Brumsack, Debra A. Willard, Stefan Schouten, Catherine E. Stickley, Matthew O’Regan, Gert-Jan Reichart, Jaap S. Sinninghe Damste, Henk Brinkhuis
Paleoecology and ecosystem restoration: Case studies from Chesapeake Bay and the Florida Everglades Paleoecology 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...
Authors
Debra A. Willard, Thomas M. Cronin
Marl prairie vegetation response to 20th century hydrologic change Marl 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...
Authors
Christopher E. Bernhardt, Debra A. Willard
Synthesis of age data and chronology for Florida Bay and Biscayne Bay cores collected for ecosystem history of South Florida’s estuaries project Synthesis 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...
Authors
G. Lynn Wingard, J.W. Hudley, C. W. Holmes, Debra A. Willard, M. Marot
USGS Tampa Bay Pilot Study USGS 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...
Authors
K. K. Yates, T. M. Cronin, M. Crane, M. Hansen, A. Nayeghandi, P. Swarzenski, T. Edgar, G. R. Brooks, B. Suthard, A. Hine, S. Locker, Debra A. Willard, D. Hastings, B. Flower, D. Hollander, R.A. Larson, K. Smith
Deglacial climate variability in central Florida, USA Deglacial 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...
Authors
Debra A. Willard, C.E. Bernhardt, G. R. Brooks, T. M. Cronin, T. Edgar, R. Larson
Synthesis of U.S. Geological Survey science for the Chesapeake Bay ecosystem and implications for environmental management Synthesis 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...
Authors
Scott 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. Willard
Rapid sea level rise and ice sheet response to 8,200-year climate event Rapid 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...
Authors
T. M. Cronin, P.R. Vogt, Debra A. Willard, R. Thunell, J. Halka, M. Berke, J. Pohlman
Sea level rise in Tampa Bay 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...
Authors
T. 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. Smith
Paleoecology of the Late Pennsylvanian-age Calhoun coal bed and implications for long-term dynamics of wetland ecosystems Paleoecology 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...
Authors
Debra A. Willard, T.L. Phillips, Alicia D. Lesnikowska, William A. DiMichele
Response of Everglades tree islands to environmental change Response 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...
Authors
Debra A. Willard, Christopher E. Bernhardt, Charles W. Holmes, Bryan Landacre, Marci E. Marot
Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida Descriptions 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...
Authors
G. Lynn Wingard, Thomas M. Cronin, Charles W. Holmes, Debra A. Willard, Carlos A. Budet, Ruth E. Ortiz
*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