Karen Thorne, Ph.D.
Dr. Karen Thorne is a Research Ecologist with the USGS Western Ecological Research Center,
Her research focus is on climate change impacts to coastal ecosystems. In particular, her work has included assessing sea-level rise and storm impacts to coastal ecosystems, wetland ecology, restoration, and blue carbon. She received her Ph.D. and MS from the University of California, Davis.
Dr. Thorne's interests lie in conservation and management issues surrounding climate-related research that assess changes to ecosystems. Her current focus is assessing how sea-level rise and storms impact tidal wetland ecosystems in the U.S. and island habitats. She conducts research to inform climate adaptation and planning to help managers mitigate impacts and conduct restoration. Her research is based on field data collection methods that can be developed into climate change impact models using ArcGIS and other remote sensing tools.
RESEARCH INTERESTS
- Global Change Biology
- Coastal Ecosystems
- Wetland Ecology
- Restoration
- Threatened & Endangered Species
- Blue Carbon
- Landscape Ecology
- Ecological Response Modeling
- Storm Monitoring
- Sea-level Rise Planning & Decision Support
Professional Experience
Research Ecologist, USGS, Western Ecological Research Center, Davis Field Station, 2012 - present
Biologist, USGS, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 2005 to 2012
Research Associate, U.S. Fish & Wildlife Service, Fairbanks, AK, 2002 to 2005
Education and Certifications
PhD, Geography, Global Change, University of California, Davis, 2012
MSc, Geography, Environmental Studies, University of California, Davis, 2008
BS, Wildlife, Fish, & Conservation Biology, University of California, Davis 2000
Affiliations and Memberships*
California Landscape Conservation Cooperative Science Team
Science and Products
Cogswell Marsh
China Camp Marsh
Fagan Marsh
Laumeister Marsh
Coon Island Marsh
Colma Marsh
Coastal Ecosystem Response to Sea-level Rise
Modeling Sea-Level Rise in San Francisco Bay Estuary
Ecological Stressors - Rocky Coastlines, Mangroves, Marshes, Droughts, and Storms
Supporting Informed Responses to Sea-Level Rise
San Pablo Bay Marsh
Black John Marsh
Soil, Plant, and Elevation Characteristics of Tidal and Managed Impounded Wetlands in Suisun Marsh, California, USA (2018-2019)
WARMER-2 Model Inputs and Projections for Three Tidal Wetland Sites Across San Francisco Bay Estuary
Mangrove Elevation and Species' Responses to Sea-level Rise Across Pohnpei, Federated States of Micronesia (ver. 1.1, December 2021)
Pacific Northwest tidal marsh plant biomass from a 2017 greenhouse experiment with flooding and salinity manipulations
Impounded and tidal wetland plant diversity and composition across spatial scales, San Francisco Bay-Delta, California, USA (2016-2018)
Small mammal surveys from northern San Francisco Bay: 1998-2014
LEAN-Corrected Collier County DEM for wetlands
LEAN-Corrected DEM for Suisun Marsh
LEAN-corrected San Francisco Bay digital elevation model, 2018
Digital elevation model outputs from wetland accreting rate model of ecosystem resilience (WARMER) at ten year intervals from 2010-2110
Data for climate-related variation in plant peak biomass and growth phenology across Pacific Northwest tidal marshes
Decomposition of plant litter in Pacific coast tidal marshes, 2014-2015
Atmospheric river storm flooding influences tidal marsh elevation building processes
Elevations of mangrove forests of Pohnpei, Micronesia
Seasonal impoundment management reduces nitrogen cycling but not resilience to surface fire in a tidal wetland
Enhancing marsh elevation using sediment augmentation: A case study from southern California, USA
Incorporation of uncertainty to improve projections of tidal wetland elevation and carbon accumulation with sea-level rise
Climate change vulnerability assessment for the California coastal national monument—Trinidad and Point Arena-Stornetta units
Sea-level rise vulnerability of mangrove forests on the Micronesian Island of Pohnpei
Intensity of grass invasion negatively correlated with population density and age structure of an endangered dune plant across its range
Wetlands in intermittently closed estuaries can build elevations to keep pace with sea-level rise
Distribution, abundance, and genomic diversity of the endangered antioch dunes evening primrose (Oenothera deltoides subsp. howellii) surveyed in 2019
Mangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia
Seasonal impoundment alters patterns of tidal wetland plant diversity across spatial scales
Science and Products
- Science
Filter Total Items: 34
Cogswell Marsh
Cogswell marsh is located on the eastern side of south San Francisco Bay and covers 60 hectares. We surveyed 523 elevation points and 228 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores near Laumeister marsh were extrapolated to...China Camp Marsh
The marsh in China Camp State Park is located on the western side of San Pablo Bay and covers 97 hectares. We surveyed 753 elevation points and 423 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores were used as input for the WARMER...Fagan Marsh
Fagan marsh is located along the Napa River and covers 68 hectares. We surveyed 481 elevation points and 241 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores at Coon Island marsh were extrapolated to Fagan marsh and used as input...Laumeister Marsh
Laumeister marsh is located on the western side of south San Francisco Bay and covers 37 hectares. We surveyed 717 elevation points and 72 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores at a nearby marsh (Whale’s Tail) were used...Coon Island Marsh
Coon Island marsh is located along the Napa River and covers 99 hectares. We surveyed 799 elevation points and 364 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores were used as input for the WARMER sea-level rise response model...Colma Marsh
Colma marsh is located on the western side of south San Francisco Bay and covers 25 hectares. We surveyed 537 elevation points to determine baseline conditions of the marsh; no vegetation surveys were conducted. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores near Laumeister marsh were...Coastal Ecosystem Response to Sea-level Rise
USGS WERC’s Dr. Karen Thorne, her team of reseachers, and her partners are currently taking a local site network approach to describe current and future conditions and projected responses of coastal ecosystems to sea-level rise and other stressors. The Coastal Ecosystem Response to Climate Change (CERCC) program’s goal is to understand how ecosystems vary in their ability to keep up with sea-level...Modeling Sea-Level Rise in San Francisco Bay Estuary
With sea level rise, how will the coastal habitats of the San Francisco Bay Estuary change over the next 100 years? Mapping and modeling studies by Dr. Karen Thorne, WERC scientists, and partners have produced scenarios for this important coastal ecosystem.Ecological Stressors - Rocky Coastlines, Mangroves, Marshes, Droughts, and Storms
Coastal estuaries that contain marshes and mangroves are currently being reshaped by changing ocean and atmospheric conditions through prolong drought, sea-level rise and increased extreme storm events. Many projected increases in sea-level are expected to result in loss of tidal wetlands and their component species. In addition, changing sediment loads, extreme tide and storm events, and shifting...Supporting Informed Responses to Sea-Level Rise
To facilitate communication and outreach of sea level rise research results and implications, Dr. Karen Thorne and members of USGS WERC are hosting in-person workshops along the Pacific coast at different sites in Washington, Oregon, and California.San Pablo Bay Marsh
The marsh at San Pablo Bay National Wildlife Refuge is located at the north side of San Pablo Bay and covers 1411 hectares. We surveyed 1,396 elevation points and 888 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores at China Camp...Black John Marsh
Black John marsh is located along the Petaluma River and covers 25 hectares. We surveyed 217 elevation points and 110 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores at Petaluma marsh were extrapolated to Black John Ecological... - Data
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Soil, Plant, and Elevation Characteristics of Tidal and Managed Impounded Wetlands in Suisun Marsh, California, USA (2018-2019)
These datasets provide information on soil properties, plant species cover, and soil surface elevation in a tidal wetland and a managed impounded wetland in northern Suisun Marsh, California, USA. These data support the following publication: Jones, S.F., Schutte, C.A., Roberts, B.J. and Thorne, K.M., 2022. Seasonal impoundment management reduces nitrogen cycling but not resilience to surfaWARMER-2 Model Inputs and Projections for Three Tidal Wetland Sites Across San Francisco Bay Estuary
Understanding the rates and patterns of tidal wetland elevation changes relative to sea-level is essential for understanding the extent of potential wetland loss over the coming years. Using an enhanced and more flexible modeling framework of an ecosystem model (WARMER-2), we explored sea-level rise (SLR) impacts on wetland elevations and carbon sequestration rates through 2100 by considering planMangrove Elevation and Species' Responses to Sea-level Rise Across Pohnpei, Federated States of Micronesia (ver. 1.1, December 2021)
Future sea-level rise poses a risk to mangrove forests. To better understand potential vulnerability, we developed a new numerical model of soil elevation for mangrove forests. We used the model to generate projections of elevation and mangrove forest composition change under four sea-level rise scenarios through 2100 (37, 52, 67, and 117 cm by 2100). We employed a data-driven modeling approach, uPacific Northwest tidal marsh plant biomass from a 2017 greenhouse experiment with flooding and salinity manipulations
The sensitivity of tidal marshes to environmental changes that result from sea-level rise or drought conditions is uncertain. We used a controlled greenhouse experiment and factorial flooding x salinity treatments to explore the differential responses of three tidal marsh plant species. Each species exhibited unique responses, with negative responses to increased salinity and longer flooding, butImpounded and tidal wetland plant diversity and composition across spatial scales, San Francisco Bay-Delta, California, USA (2016-2018)
These datasets provide information on plant alpha, beta, and gamma diversity, and plant species abundance at several spatial scales for tidal wetlands along a salinity gradient in the San Francisco Bay-Delta and an impounded brackish wetland complex in Suisun Marsh, California. Files include diversity metrics calculated at the patch, site, and region scales, average percent cover of wetland dominaSmall mammal surveys from northern San Francisco Bay: 1998-2014
This datasets summarizes small mammal trapping efforts that USGS San Francisco Bay Estuary Field Station has led, co-led, or supervised, to detect and monitor the endangered salt marsh harvest mouse (Reithrodontomys raviventris) in the northern reaches of San Francisco Bay from 1998-2014. As the salt marsh harvest mouse is listed as endangered under the Endangered Species Act, sensitive locationLEAN-Corrected Collier County DEM for wetlands
Lidar-derived digital elevation models often contain a vertical bias due to vegetation. In areas with tidal influence the amount of bias can be ecologically significant, for example, by decreasing the expected inundation frequency. We generated a corrected digital elevation model (DEM) for wetlands throughout Collier county using a modification of the Lidar Elevation Adjustment with NDVI (LEAN) teLEAN-Corrected DEM for Suisun Marsh
Lidar-derived digital elevation models often contain a vertical bias due to vegetation. In areas with tidal influence the amount of bias can be ecologically significant, for example, by decreasing the expected inundation frequency. We generated a corrected digital elevation mode (DEM) for Suisun marsh using a modification of the Lidar Elevation Adjustment with NDVI (LEAN) technique (Buffington etLEAN-corrected San Francisco Bay digital elevation model, 2018
Lidar-derived digital elevation models often contain a vertical bias due to vegetation. In areas with tidal influence the amount of bias can be ecologically significant, for example, by decreasing the expected inundation frequency. We generated a corrected digital elevation mode (DEM) for tidal marsh areas around San Francisco Bay using the Lidar Elevation Adjustment with NDVI (LEAN) technique (BuDigital elevation model outputs from wetland accreting rate model of ecosystem resilience (WARMER) at ten year intervals from 2010-2110
Digital elevation model outputs from wetland accreting rate model of ecosystem resilience (WARMER) at ten year intervals from 2010-2110. Baseline elevations were collected with RTK GPS units and LiDAR elevations in non-surveyed areas were also corrected using LEAN method. Historical accretion rates were collected at each salt marsh and used to parameterize WARMER, predicting future elevations.Data for climate-related variation in plant peak biomass and growth phenology across Pacific Northwest tidal marshes
This data release is comprised of tidal marsh biomass data and spatial predictions of peak biomass and Julian day of peak biomass using data from the Landsat archive. Aboveground biomass dry weight of mixed-species plots (25x50 cm) at a tidal marsh in Willapa Bay, Washington were used to establish a relationship between biomass and tasseled cap greeness (TCG). The julian day of annual peak greenneDecomposition of plant litter in Pacific coast tidal marshes, 2014-2015
Decomposition of plant matter is one of the key processes affecting carbon cycling and storage in tidal wetlands. In this study, we evaluated the effects of factors related to climate change (temperature, inundation) and vegetation composition on rates of litter decay in seven tidal marsh sites along the Pacific coast. In 2014 we conducted manipulative experiments to test inundation effects on lit - Multimedia
- Publications
Filter Total Items: 59
Atmospheric river storm flooding influences tidal marsh elevation building processes
Disturbances are a key component of ecological processes in coastal ecosystems. Investigating factors that affect tidal marsh accretion and elevation change is important, largely due to accelerating sea-level rise and the ecological and economic value of wetlands. Sediment accumulation rates, elevation change, and flooding were examined at five marshes along a riverine-tidal gradient in the northeAuthorsKaren M. Thorne, Scott Jones, Chase M. Freeman, Kevin J. Buffington, Christopher N. Janousek, Glenn R. GuntenspergenElevations of mangrove forests of Pohnpei, Micronesia
Mangrove surface elevation is the crux of mangrove vulnerability to sea level rise. Local topography influences critical periods of tidal inundation that govern distributions of mangrove species and dictates future distributions. This study surveyed ground surface elevations of the extensive mangroves of Pohnpei, Federated States of Micronesia, integrating four survey technologies to solve issuesAuthorsJoanna C Ellison, Kevin J. Buffington, Karen M. Thorne, Dean B. Gesch, Jeffrey Irwin, Jeffrey J. DanielsonSeasonal impoundment management reduces nitrogen cycling but not resilience to surface fire in a tidal wetland
Hydrology and salinity regimes of many impounded wetlands are manipulated to provide seasonal habitats for migratory waterfowl, with little-known consequences for ecosystem structure and function. Managed hydrology can alter ecosystems by directly changing soil properties and processes and by influencing plant community dynamics. Additionally, management history may influence ecosystem response toAuthorsScott Jones, Charles A Schutte, Brian J Roberts, Karen M. ThorneEnhancing marsh elevation using sediment augmentation: A case study from southern California, USA
Tidal marshes are an important component of estuaries that provide habitat for fish and wildlife, protection from flooding, recreation opportunities, and can improve water quality. Critical to maintaining these functions is vertical accretion, a key mechanism by which tidal marshes build elevation relative to local sea level. The beneficial use of dredged material to build marsh elevations in respAuthorsEvyan Borgnis Sloane, Karen M. Thorne, Christine R Whitcraft, Victoria TouchstoneIncorporation of uncertainty to improve projections of tidal wetland elevation and carbon accumulation with sea-level rise
Understanding the rates and patterns of tidal wetland elevation changes relative to sea-level is essential for understanding the extent of potential wetland loss over the coming years. Using an enhanced and more flexible modeling framework of an ecosystem model (WARMER-2), we explored sea-level rise (SLR) impacts on wetland elevations and carbon sequestration rates through 2100 by considering planAuthorsKevin J. Buffington, Christopher N. Janousek, Bruce D. Dugger, John C. Callaway, Lisa Schile-Beers, Evyan Borgnis Sloane, Karen M. ThorneClimate change vulnerability assessment for the California coastal national monument—Trinidad and Point Arena-Stornetta units
Executive SummaryThe California Coastal National Monument protects islets, reefs, and rock outcropping habitats in six onshore units, including the Trinidad and Point Arena-Stornetta Units.The California Coastal National Monument provides crucial habitat for resident and migratory species of seabirds, marine mammals, and invertebrates, which includes several federally listed threatened and endangeAuthorsKaren M. Thorne, Chase M. Freeman, Kevin J. Buffington, Susan E.W. De La CruzSea-level rise vulnerability of mangrove forests on the Micronesian Island of Pohnpei
IntroductionThe mangrove forests across the Federated States of Micronesia provide critical resources and contribute to climate resilience. Locally, mangrove forests provide habitat for fish and wildlife, timber, and other cultural resources. Mangrove forests also protect Micronesian communities from tropical cyclones and tsunamis, providing a buffer against powerful waves and winds. Mangrove foreAuthorsKaren M. Thorne, Kevin J. BuffingtonIntensity of grass invasion negatively correlated with population density and age structure of an endangered dune plant across its range
Invasive species are a global threat to ecosystem biodiversity and function; non-native grass invasion has been particularly problematic in sparsely vegetated ecosystems such as open dunes. Native plant population responses to invasion, however, are infrequently translated to landscape scales, limiting the effectiveness of these data for addressing conservation issues. We quantified population denAuthorsScott Jones, Anna Kennedy, Chase M. Freeman, Karen M. ThorneWetlands in intermittently closed estuaries can build elevations to keep pace with sea-level rise
Sea-level rise is a threat to coastal ecosystems, which have important conservation and economic value. While marsh response to sea-level rise has been well characterized for perennially open estuaries, bar-built intermittently-closed estuaries and their sea-level rise response are seldom addressed in the literature – despite being common globally. We seek to advance the conceptual understanding oAuthorsKaren M. Thorne, Kevin J. Buffington, Scott Jones, John L. LargierDistribution, abundance, and genomic diversity of the endangered antioch dunes evening primrose (Oenothera deltoides subsp. howellii) surveyed in 2019
Sand dune ecosystems are highly dynamic landforms found along coastlines and riverine deltas where a supply of sand-sized material is available to be delivered by aquatic and wind environments. These unique ecosystems provide habitat for a variety of endemic and rare plant and animal species. Sand dunes have been affected by human development, sand mining, and shoreline stabilization from invasiveMangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia
Mangrove forests are likely vulnerable to accelerating sea-level rise; however, we lack the tools necessary to understand their future resilience. On the Pacific island of Pohnpei, Federated States of Micronesia, mangroves are habitat to endangered species and provide critical ecosystem services that support local communities. We developed a generalizable modeling framework for mangroves that accoAuthorsKevin J. Buffington, Richard A. MacKenzie, Joel A. Carr, Maybeleen Apwong, Ken W. Krauss, Karen M. ThorneSeasonal impoundment alters patterns of tidal wetland plant diversity across spatial scales
Understanding patterns of biodiversity is a key goal of ecology and is especially pressing in the current human‐caused biodiversity crisis. In wetland ecosystems, human impacts are centered around hydrologic manipulation including the common practice of wetland diking and impoundment. Constraining how wetland management influences plant biodiversity patterns across spatial scales will provide infoAuthorsScott Jones, Christopher N. Janousek, Michael L. Casazza, John Y. Takekawa, Karen M. Thorne - 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