Christian E Torgersen
I am a Supervisory Research Wildlife Biologist at the Forest and Rangeland Ecosystem Science Center
My research interests include landscape ecology, riverine landscapes, watershed processes, ecological scaling, water quality, fish habitat, land use/land cover change, landscape scenario modeling, spatial analysis, remote sensing and GIS.
Professional Experience
2002 - Present: USGS Forest and Rangeland Ecosystem Science Center, Supervisory Research Wildlife Biologist, Seattle, WA
Education and Certifications
Ph.D., Fisheries Science, Oregon State University, Corvallis, OR (2002)
M.S., Fisheries Science, Geography Minor, Oregon State University, Corvallis, OR (1996)
B.A., Geography/German, double major, University of Oregon, Eugene, OR (1993)
Science and Products
Aquatic & Landscape Ecology Research Team (FRESC)
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Projecting spatiotemporally explicit effects of climate change on stream temperature: A model comparison and implications for coldwater fishes
Longitudinal, lateral, vertical, and temporal thermal heterogeneity in a large impounded river: Implications for cold-water refuges
Lidar-based approaches for estimating solar insolation in heavily forested streams
Conceptualizing ecological responses to dam removal: If you remove it, what's to come?
Modeling intrinsic potential for beaver (Castor canadensis) habitat to inform restoration and climate change adaptation
Simulated juvenile salmon growth and phenology respond to altered thermal regimes and stream network shape
Longitudinal thermal heterogeneity in rivers and refugia for coldwater species: Effects of scale and climate change
Dam removal: Listening in
Landscape context and the biophysical response of rivers to dam removal in the United States
Envisioning, quantifying, and managing thermal regimes on river networks
Status and trends of dam removal research in the United States
Spatial variability of Chinook salmon spawning distribution and habitat preferences
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.
Science and Products
- Science
Aquatic & Landscape Ecology Research Team (FRESC)
Fresh waters are one of the most valuable and threatened resources worldwide. They supply critical services to society and harbor many of the world’s most imperiled species. We conduct research and provide technical assistance to address challenges to fresh waters. Our research focuses on ecological processes in freshwater and terrestrial systems and the effects of those processes on landscape... - Data
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
- Multimedia
- Publications
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 59Projecting spatiotemporally explicit effects of climate change on stream temperature: A model comparison and implications for coldwater fishes
Conservation planners and resource managers seek information about how the availability and locations of cold-water habitats will change in the future and how these predictions vary among models. We used a physical process-based model to demonstrate the implications of climate change for streamflow and water temperature in two watersheds with distinctive flow regimes: the Snoqualmie watershed (WA)AuthorsSe Yeun Lee, Aimee H. Fullerton, Ning Sun, Christian E. TorgersenLongitudinal, lateral, vertical, and temporal thermal heterogeneity in a large impounded river: Implications for cold-water refuges
Dam operations can affect mixing of the water column, thereby influencing thermal heterogeneity spatially and temporally. This occurs by restricting or eliminating connectivity in longitudinal, lateral, vertical, and temporal dimensions. We examined thermal heterogeneity across space and time and identified potential cold-water refuges for salmonids in a large impounded river in inland northwesterAuthorsFrancine H. Mejia, Christian E. Torgersen, Eric K Berntsen, Joseph R Maroney, J M Connor, Aimee H. Fullerton, Joseph L. Ebersole, Mark L LorangLidar-based approaches for estimating solar insolation in heavily forested streams
Methods to quantify solar insolation in riparian landscapes are needed due to the importance of stream temperature to aquatic biota. We have tested three lidar predictors using two approaches developed for other applications of estimating solar insolation from airborne lidar using field data collected in a heavily forested narrow stream in western Oregon, USA. We show that a raster methodology basAuthorsJeffrey J Richardson, Christian E. Torgersen, L Monika MoskalConceptualizing ecological responses to dam removal: If you remove it, what's to come?
One of the desired outcomes of dam decommissioning and removal is the recovery of aquatic and riparian ecosystems. To investigate this common objective, we synthesized information from empirical studies and ecological theory into conceptual models that depict key physical and biological links driving ecological responses to removing dams. We define models for three distinct spatial domains: upstreAuthorsJ. Ryan Bellmore, George R. Pess, Jeffrey J. Duda, Jim E. O'Connor, Amy E. East, Melissa M. Foley, Andrew C. Wilcox, Jon J. Major, Patrick B. Shafroth, Sarah A. Morley, Christopher S. Magirl, Chauncey W. Anderson, James E. Evans, Christian E. Torgersen, Laura S. CraigByEcosystems Mission Area, Coastal and Marine Hazards and Resources Program, Species Management Research Program, Arizona Water Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, Geology, Minerals, Energy, and Geophysics Science Center, John Wesley Powell Center for Analysis and Synthesis, Oregon Water Science Center, Pacific Coastal and Marine Science Center, Western Fisheries Research CenterModeling intrinsic potential for beaver (Castor canadensis) habitat to inform restoration and climate change adaptation
Through their dam-building activities and subsequent water storage, beaver have the potential to restore riparian ecosystems and offset some of the predicted effects of climate change by modulating streamflow. Thus, it is not surprising that reintroducing beaver to watersheds from which they have been extirpated is an often-used restoration and climate-adaptation strategy. Identifying sites for reAuthorsBenjamin J. Dittbrenner, Michael M. Pollack, Jason W. Schilling, Julian D. Olden, Joshua J. Lawler, Christian E. TorgersenSimulated juvenile salmon growth and phenology respond to altered thermal regimes and stream network shape
It is generally accepted that climate change will stress coldwater species such as Pacific salmon. However, it is unclear what aspect of altered thermal regimes (e.g., warmer winters, springs, summers, or increased variability) will have the greatest effect, and what role the spatial properties of river networks play. Thermally diverse habitats may afford protection from climate change by providinAuthorsAimee H. Fullerton, Brian J. Burke, Joshua J. Lawler, Christian E. Torgersen, Joseph L. Ebersole, Scott G. LeibowitzLongitudinal thermal heterogeneity in rivers and refugia for coldwater species: Effects of scale and climate change
Climate-change driven increases in water temperature pose challenges for aquatic organisms. Predictions of impacts typically do not account for fine-grained spatiotemporal thermal patterns in rivers. Patches of cooler water could serve as refuges for anadromous species like salmon that migrate during summer. We used high-resolution remotely sensed water temperature data to characterize summer therAuthorsA.H. Fullerton, Christian E. Torgersen, J.J. Lawer, E. A. Steel, J. L. Ebersole, S.Y. LeeDam removal: Listening in
Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus farAuthorsMelissa M. Foley, James Bellmore, James E. O'Connor, Jeffrey J. Duda, Amy E. East, Gordon G. Grant, Chauncey W. Anderson, Jennifer A. Bountry, Mathias J. Collins, Patrick J. Connolly, Laura S. Craig, James E. Evans, Samantha Greene, Francis J. Magilligan, Christopher S. Magirl, Jon J. Major, George R. Pess, Timothy J. Randle, Patrick B. Shafroth, Christian E. Torgersen, Desiree D. Tullos, Andrew C. WilcoxByEcosystems Mission Area, Natural Hazards Mission Area, Water Resources Mission Area, Volcano Hazards Program, Forest and Rangeland Ecosystem Science Center, John Wesley Powell Center for Analysis and Synthesis, Oregon Water Science Center, Pacific Coastal and Marine Science Center, Volcano Science Center, Western Fisheries Research Center, Columbia River Research Laboratory (CRRL)Landscape context and the biophysical response of rivers to dam removal in the United States
Dams have been a fundamental part of the U.S. national agenda over the past two hundred years. Recently, however, dam removal has emerged as a strategy for addressing aging, obsolete infrastructure and more than 1,100 dams have been removed since the 1970s. However, only 130 of these removals had any ecological or geomorphic assessments, and fewer than half of those included before- and after-remoAuthorsMelissa M. Foley, Francis J. Magilligan, Christian E. Torgersen, Jon J. Major, Chauncey W. Anderson, Patrick J. Connolly, Daniel J. Wieferich, Patrick B. Shafroth, James E. Evans, Dana M. Infante, Laura CraigByEcosystems Mission Area, Water Resources Mission Area, Science Synthesis, Analysis and Research Program, Science Analytics and Synthesis (SAS) Program, Forest and Rangeland Ecosystem Science Center, John Wesley Powell Center for Analysis and Synthesis, Oregon Water Science Center, Pacific Coastal and Marine Science CenterEnvisioning, quantifying, and managing thermal regimes on river networks
Water temperatures fluctuate in time and space, creating diverse thermal regimes on river networks. Temporal variability in these thermal landscapes has important biological and ecological consequences because of nonlinearities in physiological reactions; spatial diversity in thermal landscapes provides aquatic organisms with options to maximize growth and survival. However, human activities andAuthorsE. Ashley Steel, Timothy J. Beechie, Christian E. Torgersen, Aimee H. FullertonStatus and trends of dam removal research in the United States
Aging infrastructure coupled with growing interest in river restoration has driven a dramatic increase in the practice of dam removal. With this increase, there has been a proliferation of studies that assess the physical and ecological responses of rivers to these removals. As more dams are considered for removal, scientific information from these dam-removal studies will increasingly be called uAuthorsJames Bellmore, Jeffrey J. Duda, Laura Craig, Samantha L. Greene, Christian E. Torgersen, Mathias J. Collins, Katherine VittumSpatial variability of Chinook salmon spawning distribution and habitat preferences
We investigated physical habitat conditions associated with the spawning sites of Chinook Salmon Oncorhynchus tshawytscha and the interannual consistency of spawning distribution across multiple spatial scales using a combination of spatially continuous and discrete sampling methods. We conducted a census of aquatic habitat in 76 km of the upper main-stem Yakima River in Washington and evaluated sAuthorsJeremy M. Cram, Christian E. Torgersen, Ryan S. Klett, George R. Pess, Darran May, Todd N. Pearsons, Andrew H. DittmanNon-USGS Publications**
Torgersen, C.E., Close, D.A., 2004, Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales: Freshwater Biology, v. 49, no. 5, p. 614-630.Fausch, K.D., Torgersen, C.E., Baxter, C.V., Li, H.W., 2002, Landscapes to riverscapes- bridging the gap between research and conservation of stream fishes: BioScience, v. 52, no. 6, p. 483-498.Torgersen, C.E., Faux, R.N., McIntosh, B.A., Poage, N., Norton, D.J., 2001, Airborne thermal remote sensing for water temperature assessment in rivers and streams: Remote Sensing of Environment, v. 76, p. 386-398.Torgersen, C.E., Price, D.M., Li, H.W., McIntosh, B.A., 1999, Multiscale thermal refugia and stream habitat associations of chinook salmon in northwestern Oregon: Ecological Applications, v. 9, no. 1, p. 301-319, https://doi.org/10.1890/1051-0761(1999)009[0301:MTRASH]2.0.CO;2.Torgersen, C.E., Poage, N., Flood, M., Norton, D.J., McIntosh, B.A., 1996, Airborne thermal remote sensing of salmonid habitat for restoration planning in Pacific Northwestern watersheds, Baltimore, MD In eds., Proceedings of the Watershed 96 Conference: Alexandria, VA, Water Environment Federation, p. 812-814.Poage, N., Torgersen, C.E., Norton, D.J., Flood, M., McIntosh, B.A., 1996, Application of thermal infrared (FLIR) and visible videography to the monitoring and restoration of salmonid habitat in the Pacific Northwest In Greer, J.D., ed., Proceedings of the Sixth Forest Service Remote Sensing Applications Conference: Denver, CO, American Society for Photogrammetry and Remote Sensing, p. 376-379.Torgersen, C.E., Jones, J.A., Moldenke, A.R., LeMaster, M.P., 1995, The spatial heterogeneity of soil invertebrates and edaphic properties in an old growth forest stand in western Oregon In Collins, H.P., Robertson, G.P., Klug, M.J., eds., The Significance and Regulation of Soil Biodiversity: Dordrecht, Netherlands, Kluwer Academic Publishers, p. 225-236.Torgersen, C.E., Price, D.M., Li, H.W., McIntosh, B.A., 1995, Thermal refugia and chinook salmon habitat in Oregon- Applications of airborne thermal videography In Mausel, P., ed., Proceedings of the 15th Biennial Workshop on Color Photography and Videography: Terre Haute, IN, American Society for Photogrammetry and Remote Sensing, p. 167-171.Torgersen, C.E., Baxter, C.V., Li, H., McIntosh, B.A., 2006, Landscape influences on longitudinal patterns of river fishes- Spatially continuous analysis of fish-habitat relationships In Hughes, R., Wang, L., Wofford, J.E., eds., Influences of Landscapes on Stream Habitats and Biological Assemblages: Bethesda, MD, American Fisheries Society, p. 473-492**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.