Karen Thorne
Biography
Dr. Karen Thorne is a Principal Investigator with the USGS Western Ecological Research Center, where her research focus is in climate change impacts to ecosystems. In particular, her work has included assessing sea-level rise and storms impacts to nearshore ecosystems, wetland ecology and wildife. She received her Ph.D. and MS from the University of California, Davis.
Dr. Thorne's interests lie in conservation issues surrounding climate-related research that assess changes to ecosystems and wildlife. Her current focus is assessing how sea-level rise and storms impact salt marsh ecosystems and local wildlife populations. In particular, Dr. Thorne is interested in how wildlife respond to high water events and how this relates to predation and breeding success. 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
- Threatened & Endangered Species
- Wildlife Biology
- Landscape Ecology
- Ecological Response Modeling
- Storm Monitoring
- Sea-level Rise Planning & Decision Support
EDUCATION
• 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
COMMITTEES
• California Landscape Conservation Cooperative Science Team
PROFESSIONAL EXPERIENCE
• Biologist, USGS, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 2005 to present
• Research Associate, U.S. Fish & Wildlife Service, Fairbanks, AK, 2002 to 2005
Science and Products
Using Drone Imagery to Assess Impacts of the 2018 Carr Fire
USGS WERC’s Dr. Karen Thorne and her research team are using drone imagery to understand how the 2018 Carr Fire affected ecosystems and cultural resources. The study, a collaboration with the National Park Service (NPS), focuses on Whiskeytown National Recreation Area in northern California. The drone images will help the WERC researchers identify changes in topography, cultural sites, debris...
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-...
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.
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...
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.
Davis Field Station
The Davis Field Station is home to research programs that focus on coastal ecosystem dynamics, ecological stressors, and their effects on wildlife populations. These studies primarily take place along the Pacific coast from the Aleutian Islands to southern California. Current projects investigate sea-level rise along both coasts of North America, landscape-scale aquatic and terrestrial ecology...
Improving Our Ability to Forecast Tidal Marsh Response to Sea Level Rise
Our overall objective is to understand what controls the vulnerability of coastal marshes to risks associated with global change drivers and rising sea levels. Fundamental questions pertaining to coastal wetland vulnerability still need to be addressed. What factors explain spatial and geographic variation in tidal wetland vulnerability? How do short term climatic events (storms) influence the...
LEAN-Corrected Chesapeake Bay Digital Elevation Models, 2019
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 Chesapeake Bay using a modification of the Lidar Elevation Adjustment with NDVI (LEAN) technique (...
LEAN-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...
LEAN-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...
Digital 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...
Decomposition 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...
Thin-layer sediment addition to an existing salt marsh to combat sea-level rise and improve endangered species habitat in California, USA
Current tidal marsh elevations and their accretion rates are important predictors of vulnerability to sea-level rise. When tidal marshes are at risk, adaptation measures, such as sediment addition to increase elevations, can be implemented to prevent degradation and loss. In 2016, wildlife managers prescribed a thin-layer sediment addition of...
Thorne, Karen M.; Freeman, Chase; Rosencranz, Jordan A.; Ganju, Neil Kamal; Guntenspergen, Glenn R. Flooding regimes increase avian predation on wildlife prey in tidal marsh ecosystems
Within isolated and fragmented populations, species interactions such as predation can cause shifts in community structure and demographics in tidal marsh ecosystems. It is critical to incorporate species interactions into our understanding when evaluating the effects of sea‐level rise and storm surges on tidal marshes. In this study, we...
Thorne, Karen M.; Spragens, Kyle A.; Buffington, Kevin J.; Rosencranz, Jordan A.; Takekawa, John El Niño increases high‐tide flooding in tidal wetlands along the U.S. Pacific coast.
Periodic oscillations between El Niño and La Niña conditions in the Pacific Basin affect oceanographic and meteorological phenomena globally, with impacts on the abundance and distribution of marine species. However, El Niño effects on estuarine hydrology and tidal wetland processes have seldom been examined rigorously. We used detailed wetland...
Goodman, Arianna; Thorne, Karen M.; Buffington, Kevin J.; Freeman, Chase; Janousek, Christopher N. Rising tides: Assessing habitat vulnerability for an endangered salt marsh-dependent species with sea-level rise
Salt marsh-dependent species are vulnerable to impacts of sea-level rise (SLR). Site-specific differences in ecogeomorphic processes result in different SLR vulnerabilities. SLR impacts to Ridgway’s rail (Rallus obsoletus) of Southern California (SC) and San Francisco Bay (SF), U.S.A. could foreshadow SLR effects on other coastal endemic species....
Rosencranz, Jordan A.; Thorne, Karen M.; Buffington, Kevin J.; Overton, Cory T.; Takekawa, John; Casazza, Michael L.; McBroom, Jennifer; Wood, Julian K.; Nur, Nadav; Zembal, Richard L.; MacDonald, Glen M.; Ambrose, Richard F. Sea‐level rise, habitat loss, and potential extirpation of a salt marsh specialist bird in urbanized landscapes
Sea‐level rise (SLR) impacts on intertidal habitat depend on coastal topology, accretion, and constraints from surrounding development. Such habitat changes might affect species like Belding's savannah sparrows (Passerculus sandwichensis beldingi; BSSP), which live in high‐elevation salt marsh in the Southern California Bight. To predict how BSSP...
Rosencranz, Jordan; Thorne, Karen M.; Buffington, Kevin J.; Takekawa, John Y.; Hechinger, Ryan F.; Stewart, Tara E.; Ambrose, Richard F.; MacDonald, Glen M.; Holmgren, Mark A.; Crooks, Jeff A.; Patton, Robert T.; Lafferty, Kevin D. Climate-related variation in plant peak biomass and growth phenology across Pacific Northwest tidal marshes
The interannual variability of tidal marsh plant phenology is largely unknown and may have important ecological consequences. Marsh plants are critical to the biogeomorphic feedback processes that build estuarine soils, maintain marsh elevation relative to sea level, and sequester carbon. We calculated Tasseled Cap Greenness, a metric of...
Buffington, Kevin J.; Dugger, Bruce D.; Thorne, Karen M. U.S. Pacific coastal wetland resilience and vulnerability to sea-level rise
We used a first-of-its-kind comprehensive scenario approach to evaluate both the vertical and horizontal response of tidal wetlands to projected changes in the rate of sea-level rise (SLR) across 14 estuaries along the Pacific coast of the continental United States. Throughout the U.S. Pacific region, we found that tidal wetlands are highly...
Thorne, Karen M.; MacDonald, Glen M.; Guntenspergen, Glenn R.; Ambrose, Richard F.; Buffington, Kevin J.; Dugger, Bruce D.; Freeman, Chase; Janousek, Christopher; Brown, Lauren N.; Rosencranz, Jordan A.; Homquist, James; Smol, John P.; Hargan, Kathryn; Takekawa, John Y. Inundation, vegetation, and sediment effects on litter decomposition in Pacific Coast tidal marshes
The cycling and sequestration of carbon are important ecosystem functions of estuarine wetlands that may be affected by climate change. We conducted experiments across a latitudinal and climate gradient of tidal marshes in the northeast Pacific to evaluate the effects of climate- and vegetation-related factors on litter decomposition. We...
Janousek, Christopher; Buffington, Kevin J.; Guntenspergen, Glenn R.; Thorne, Karen M.; Dugger, Bruce D.; Takekawa, John Y. Are coastal managers ready for climate change? A case study from estuaries along the Pacific coast of the United States
A key challenge for coastal resource managers is to plan and implement climate change adaptation strategies inlight of uncertainties and competing management priorities. In 2014, we held six workshops across estuaries along the Pacific coast of North America with over 150 participants to evaluate resource managers' perceived level of understanding...
Thorne, Karen M.; Elliott-Fisk, Deborah L.; Freeman, Chase; Bui, Thuy-Vy D.; Powelson, Katherine; Janousek, Christopher; Buffington, Kevin J.; Takekawa, John Y. Statistical correction of lidar-derived digital elevation models with multispectral airborne imagery in tidal marshes
Airborne light detection and ranging (lidar) is a valuable tool for collecting large amounts of elevation data across large areas; however, the limited ability to penetrate dense vegetation with lidar hinders its usefulness for measuring tidal marsh platforms. Methods to correct lidar elevation data are available, but a reliable method that...
Buffington, Kevin J.; Dugger, Bruce D.; Thorne, Karen M.; Takekawa, John Y. Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes...
Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.
Effects of climate change on tidal marshes along a latitudinal gradient in California
Public SummaryThe coastal region of California supports a wealth of ecosystem services including habitat provision for wildlife and fisheries. Tidal marshes, mudflats, and shallow bays within coastal estuaries link marine, freshwater and terrestrial habitats, and provide economic and recreational benefits to local communities. Climate change...
Thorne, Karen M.; MacDonald, Glen M.; Ambrose, Rich F.; Buffington, Kevin J.; Freeman, Chase M.; Janousek, Christopher N.; Brown, Lauren N.; Holmquist, James R.; Guntenspergen, Glenn R.; Powelson, Katherine W.; Barnard, Patrick L.; Takekawa, John Y.
Sea-level Rise Scenario for San Francisco Bay Estuary - Arrowhead Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Coon Island
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Laumeister Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Gambinini Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Corte Madera Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - San Pablo Bay Strip Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - West San Pablo Bay Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Petaluma Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Cogswell Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - Fagan Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - China Camp State Park
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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Sea-level Rise Scenario for San Francisco Bay Estuary - BlackJohn Marsh
How will sea level rise impact coastal ecosystems like salt marshes? Will plant species change and shift available habitat for local wildlife? Or will the marsh be completely inundated? USGS scientists are conducting extensive elevation and habitat surveys along the U.S. Pacific Coast, and using the data to model sea level rise impact for the next 100 years. This research
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New USGS-Led Study Could Help Pacific Wetlands Adapt to Sea Level Rise
SAN FRANCISCO BAY, Calif. — A new study published Wednesday in Science Advances introduces an innovative tool to help resource managers preserve Pacific coastal wetlands from rising sea levels.
Study Shows Sea Level Rise to Threaten West Coast Tidal Wetlands Over the Next 100 Years
The U.S. Geological Survey and Oregon State University released a report this week examining Pacific Northwest tidal wetland vulnerability to sea level rise. Scientists found that, while vulnerability varies from marsh to marsh, most wetlands would likely be resilient to rising sea levels over the next 50-70 years.