Skip to main content
U.S. flag

An official website of the United States government

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

link
Surveying for the FEMA project

The Influence of Climatic changes on Extreme Streamflows in the United States

Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.
By
New England Water Science Center
link

The Influence of Climatic changes on Extreme Streamflows in the United States

Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.
Learn More
link
A lab technician swirls samples in a watch glass to assist in extracting pollen

Palynology Laboratory

In this lab, we specialize in extracting pollen palynomorphs from geologic field samples. We also assist our center's scientists with outreach programs to educate students and inform policy makers as to the importance of our science.
By
Florence Bascom Geoscience Center
link

Palynology Laboratory

In this lab, we specialize in extracting pollen palynomorphs from geologic field samples. We also assist our center's scientists with outreach programs to educate students and inform policy makers as to the importance of our science.
Learn More
link
USGS science for a changing world logo

Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives

Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely extend
By
John Wesley Powell Center for Analysis and Synthesis
link

Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives

Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely extend
Learn More

Radiocarbon dates, charcoal, and polycyclic aromatic hydrocarbon (PAH) data from Great Dismal Swamp Sites GDS-519 and GDS-520

Sediment cores were collected in Great Dismal Swamp National Wildlife Refuge in November, 2017 to advance understanding of climate- and land-management driven changes in vegetation, hydrology, and fire regimes. Radiocarbon dates were obtained from samples in two cores (GDS-519-3-21-2017 and GDS-520-3-21-2017) to generate age models for the cores. Bulk sediment samples, charcoal, plant macrofossils
By
Florence Bascom Geoscience Center
Filter Total Items: 101

Shallow 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 Embay
By
Florence Bascom Geoscience Center

Pollen 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 m
By
Florence Bascom Geoscience Center

Trans-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 div
By
Ecosystems, Land Change Science Program, Climate Research and Development Program

Coastal 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 understa
By
Climate Research and Development Program, Land Change Science Program

Late Holocene vegetation, climate, and land-use impacts on carbon dynamics in the Florida Everglades

Tropical and subtropical peatlands are considered a significant carbon sink. The Florida Everglades includes 6000-km2 of peat-accumulating wetland; however, detailed carbon dynamics from different environments within the Everglades have not been extensively studied or compared. Here we present carbon accumulation rates from 13 cores and 4 different environments, including sawgrass ridges and sloug
By
Florence Bascom Geoscience Center

Reconstructing vegetation response to altered hydrology and its use for restoration, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida

We present reconstructed hydrologic and vegetation trends of the last three centuries across the Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida in order to understand the effects of 20th century water management. We analyzed pollen assemblages from cores at marsh sites along three transects to document vegetation and infer hydroperiod and water depth both before and after human a
By
Florence Bascom Geoscience Center

Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay

Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite and
By
Chesapeake Bay Activities, Geosciences and Environmental Change Science Center

Climate variability during the Medieval Climate Anomaly and Little Ice Age based on ostracod faunas and shell geochemistry from Biscayne Bay, Florida: Chapter 14

An 800-year-long environmental history of Biscayne Bay, Florida, is reconstructed from ostracod faunal and shell geochemical (oxygen, carbon isotopes, Mg/Ca ratios) studies of sediment cores from three mudbanks in the central and southern parts of the bay. Using calibrations derived from analyses of modern Biscayne and Florida Bay ostracods, palaeosalinity oscillations associated with changes in p
By
Florence Bascom Geoscience Center

Micropaleontologic record of Quaternary paleoenvironments in the Central Albemarle Embayment, North Carolina, U.S.A.

To understand the temporal and spatial variation of eustatic sea-level fluctuations, glacio–hydro–isostacy, tectonics, subsidence, geologic environments and sedimentation patterns for the Quaternary of a passive continental margin, a nearly complete stratigraphic record that is fully integrated with a three dimensional chronostratigraphic framework, and paleoenvironmental information are necessary
By
Florence Bascom Geoscience Center

Development and application of a pollen-based paleohydrologic reconstruction from the lower Roanoke River Basin, North Carolina, USA

We used pollen assemblages to reconstruct late-Holocene paleohydrologic patterns in floodplain deposits from the lower Roanoke River basin (North Carolina, southeastern USA). Using 120 surface samples from 38 transects, we documented statistical relationships between pollen assemblages, vegetation, and landforms. Backswamp pollen assemblages (long hydroperiods) are dominated by Nyssa (tupelo) and

Impacts of past climate and sea level change on Everglades wetlands: placing a century of anthropogenic change into a late-Holocene context

We synthesize existing evidence on the ecological history of the Florida Everglades since its inception ~7 ka (calibrated kiloannum) and evaluate the relative impacts of sea level rise, climate variability, and human alteration of Everglades hydrology on wetland plant communities. Initial freshwater peat accumulation began between 6 and 7 ka on the platform underlying modern Florida Bay when sea l

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 a
link

Geologic records of a warmer Arctic

This article is part of the Fall 2019 issue of the Earth Science Matters Newsletter.

Read Article
link

Planning for effective restoration in the Everglades

This article is part of the Fall 2014 issue of the Earth Science Matters Newsletter. 

Read Article

Science and Products