Christian E Torgersen
I am a Supervisory Research Landscape Ecologist 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
2005 - Present: USGS Forest and Rangeland Ecosystem Science Center, Supervisory Research Landscape Ecologist, Seattle, WA
2002 - 2005: USGS Forest and Rangeland Ecosystem Science Center, Research Biologist, Corvallis, OR
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)
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...
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.
Filter Total Items: 63
A process-based hierarchical framework for monitoring glaciated alpine headwaters A process-based hierarchical framework for monitoring glaciated alpine headwaters
Recent studies have demonstrated the geomorphic complexity and wide range of hydrologic regimes found in alpine headwater channels that provide complex habitats for aquatic taxa. These geohydrologic elements are fundamental to better understand patterns in species assemblages and indicator taxa and are necessary to aquatic monitoring protocols that aim to track changes in physical...
Authors
Anne Weekes, Christian E. Torgersen, David Montgomery, Andrea Woodward, Susan Bolton
Predicting spread of invasive exotic plants into dewatered reservoirs after dam removal on the Elwha River, Olympic National Park, Washington Predicting spread of invasive exotic plants into dewatered reservoirs after dam removal on the Elwha River, Olympic National Park, Washington
The National Park Service is planning to start the restoration of the Elwha River ecosystem in Olympic National Park by removing two high head dams beginning in 2011. The potential for dispersal of exotic plants into dewatered reservoirs following dam removal, which would inhibit restoration of native vegetation, is of great concern. We focused on predicting long-distance dispersal of...
Authors
Andrea Woodward, Christian Torgersen, Joshua Chenoweth, Katherine Beirne, Steve Acker
Temperature-associated population diversity in salmon confers benefits to mobile consumers Temperature-associated population diversity in salmon confers benefits to mobile consumers
Habitat heterogeneity can generate intraspecific diversity through local adaptation of populations. While it is becoming increasingly clear that population diversity can increase stability in species abundance, less is known about how population diversity can benefit consumers that can integrate across population diversity in their prey. Here we demonstrate cascading effects of thermal
Authors
Casey Ruff, Daniel Schindle, Jonathan B. Armstrong, Kale Bentle, Gabriel Brooks, Gordon W. Holtgrieve, Molly McGlauflin, Christian E. Torgersen, James Seeb
Hydrological connectivity for riverine fish: measurement challenges and research opportunities Hydrological connectivity for riverine fish: measurement challenges and research opportunities
In this review, we first summarize how hydrologic connectivity has been studied for riverine fish capable of moving long distances, and then identify research opportunities that have clear conservation significance. Migratory species, such as anadromous salmonids, are good model organisms for understanding ecological connectivity in rivers because the spatial scale over which movements...
Authors
A.H. Fullerton, K.M. Burnett, E.A. Steel, R.L. Flitcroft, G.R. Pess, B.E. Feist, Christian Torgersen, D. Miller, B.L. Sanderson
Predicting recolonization patterns and interactions between potamodromous and anadromous salmonids in response to dam removal in the Elwha River, Washington State, USA Predicting recolonization patterns and interactions between potamodromous and anadromous salmonids in response to dam removal in the Elwha River, Washington State, USA
The restoration of salmonids in the Elwha River following dam removal will cause interactions between anadromous and potamodromous forms as recolonization occurs in upstream and downstream directions. Anadromous salmonids are expected to recolonize historic habitats, and rainbow trout (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus) isolated above the dams for 90 years are...
Authors
S.J. Brenkman, G.R. Pess, C.E. Torgersen, K.K. Kloehn, J.J. Duda, S.C. Corbett
Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon
The Lower Crooked River is a remarkable groundwater-fed stream flowing through vertical basalt canyons in the Deschutes River Valley ecoregion in central Oregon (Pater and others, 1998). The 9-mile section of the river between the Crooked River National Grasslands boundary near Ogden Wayside and river mile (RM) 8 is protected under the National Wild and Scenic Rivers Act (16 U.S.C. 1271...
Authors
Christian E. Torgersen, David Hockman-Wert, Douglas S. Bateman, David W. Leer, Robert E. Gresswell
A spatially explicit approach for evaluating relationships among coastal cutthroat trout, habitat, and disturbance in small Oregon streams A spatially explicit approach for evaluating relationships among coastal cutthroat trout, habitat, and disturbance in small Oregon streams
Abstract has not been submitted
Authors
R. E. Gresswell, C.E. Torgersen, D.S. Bateman, T.J. Guy, S.R. Hendricks, J. Wofford
Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution
We evaluate the efficacy of single-pass electrofishing without blocknets as a tool for collecting spatially continuous fish distribution data in headwater streams. We compare spatial patterns in abundance, sampling effort, and length-frequency distributions from single-pass sampling of coastal cutthroat trout (Oncorhynchus clarki clarki) to data obtained from a more precise multiple-pass...
Authors
Douglas Bateman, Robert Gresswell, Christian Torgersen
A geostatistical approach for describing spatial pattern in stream networks A geostatistical approach for describing spatial pattern in stream networks
The shape and configuration of branched networks influence ecological patterns and processes. Recent investigations of network influences in riverine ecology stress the need to quantify spatial structure not only in a two-dimensional plane, but also in networks. An initial step in understanding data from stream networks is discerning non-random patterns along the network. On the other...
Authors
L.M. Ganio, C.E. Torgersen, R. E. Gresswell
Describing spatial pattern in stream networks: A practical approach Describing spatial pattern in stream networks: A practical approach
The shape and configuration of branched networks influence ecological patterns and processes. Recent investigations of network influences in riverine ecology stress the need to quantify spatial structure not only in a two-dimensional plane, but also in networks. An initial step in understanding data from stream networks is discerning non-random patterns along the network. On the other...
Authors
L.M. Ganio, C.E. Torgersen, R. E. Gresswell
Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales
1. Spatial patterns in channel morphology and substratum composition at small (1–10 metres) and large scales (1–10 kilometres) were analysed to determine the influence of habitat heterogeneity on the distribution and abundance of larval lamprey. 2. We used a nested sampling design and multiple logistic regression to evaluate spatial heterogeneity in the abundance of larval Pacific...
Authors
Christian E. Torgersen, David Close
Pattern detection in stream networks: Quantifying spatial variability in fish distribution Pattern detection in stream networks: Quantifying spatial variability in fish distribution
Biological and physical properties of rivers and streams are inherently difficult to sample and visualize at the resolution and extent necessary to detect fine-scale distributional patterns over large areas. Satellite imagery and broad-scale fish survey methods are effective for quantifying spatial variability in biological and physical variables over a range of scales in marine...
Authors
Christian Torgersen, Robert Gresswell, Douglas Bateman
Non-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.
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.
Science and Products
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...
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.
Filter Total Items: 63
A process-based hierarchical framework for monitoring glaciated alpine headwaters A process-based hierarchical framework for monitoring glaciated alpine headwaters
Recent studies have demonstrated the geomorphic complexity and wide range of hydrologic regimes found in alpine headwater channels that provide complex habitats for aquatic taxa. These geohydrologic elements are fundamental to better understand patterns in species assemblages and indicator taxa and are necessary to aquatic monitoring protocols that aim to track changes in physical...
Authors
Anne Weekes, Christian E. Torgersen, David Montgomery, Andrea Woodward, Susan Bolton
Predicting spread of invasive exotic plants into dewatered reservoirs after dam removal on the Elwha River, Olympic National Park, Washington Predicting spread of invasive exotic plants into dewatered reservoirs after dam removal on the Elwha River, Olympic National Park, Washington
The National Park Service is planning to start the restoration of the Elwha River ecosystem in Olympic National Park by removing two high head dams beginning in 2011. The potential for dispersal of exotic plants into dewatered reservoirs following dam removal, which would inhibit restoration of native vegetation, is of great concern. We focused on predicting long-distance dispersal of...
Authors
Andrea Woodward, Christian Torgersen, Joshua Chenoweth, Katherine Beirne, Steve Acker
Temperature-associated population diversity in salmon confers benefits to mobile consumers Temperature-associated population diversity in salmon confers benefits to mobile consumers
Habitat heterogeneity can generate intraspecific diversity through local adaptation of populations. While it is becoming increasingly clear that population diversity can increase stability in species abundance, less is known about how population diversity can benefit consumers that can integrate across population diversity in their prey. Here we demonstrate cascading effects of thermal
Authors
Casey Ruff, Daniel Schindle, Jonathan B. Armstrong, Kale Bentle, Gabriel Brooks, Gordon W. Holtgrieve, Molly McGlauflin, Christian E. Torgersen, James Seeb
Hydrological connectivity for riverine fish: measurement challenges and research opportunities Hydrological connectivity for riverine fish: measurement challenges and research opportunities
In this review, we first summarize how hydrologic connectivity has been studied for riverine fish capable of moving long distances, and then identify research opportunities that have clear conservation significance. Migratory species, such as anadromous salmonids, are good model organisms for understanding ecological connectivity in rivers because the spatial scale over which movements...
Authors
A.H. Fullerton, K.M. Burnett, E.A. Steel, R.L. Flitcroft, G.R. Pess, B.E. Feist, Christian Torgersen, D. Miller, B.L. Sanderson
Predicting recolonization patterns and interactions between potamodromous and anadromous salmonids in response to dam removal in the Elwha River, Washington State, USA Predicting recolonization patterns and interactions between potamodromous and anadromous salmonids in response to dam removal in the Elwha River, Washington State, USA
The restoration of salmonids in the Elwha River following dam removal will cause interactions between anadromous and potamodromous forms as recolonization occurs in upstream and downstream directions. Anadromous salmonids are expected to recolonize historic habitats, and rainbow trout (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus) isolated above the dams for 90 years are...
Authors
S.J. Brenkman, G.R. Pess, C.E. Torgersen, K.K. Kloehn, J.J. Duda, S.C. Corbett
Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon
The Lower Crooked River is a remarkable groundwater-fed stream flowing through vertical basalt canyons in the Deschutes River Valley ecoregion in central Oregon (Pater and others, 1998). The 9-mile section of the river between the Crooked River National Grasslands boundary near Ogden Wayside and river mile (RM) 8 is protected under the National Wild and Scenic Rivers Act (16 U.S.C. 1271...
Authors
Christian E. Torgersen, David Hockman-Wert, Douglas S. Bateman, David W. Leer, Robert E. Gresswell
A spatially explicit approach for evaluating relationships among coastal cutthroat trout, habitat, and disturbance in small Oregon streams A spatially explicit approach for evaluating relationships among coastal cutthroat trout, habitat, and disturbance in small Oregon streams
Abstract has not been submitted
Authors
R. E. Gresswell, C.E. Torgersen, D.S. Bateman, T.J. Guy, S.R. Hendricks, J. Wofford
Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution
We evaluate the efficacy of single-pass electrofishing without blocknets as a tool for collecting spatially continuous fish distribution data in headwater streams. We compare spatial patterns in abundance, sampling effort, and length-frequency distributions from single-pass sampling of coastal cutthroat trout (Oncorhynchus clarki clarki) to data obtained from a more precise multiple-pass...
Authors
Douglas Bateman, Robert Gresswell, Christian Torgersen
A geostatistical approach for describing spatial pattern in stream networks A geostatistical approach for describing spatial pattern in stream networks
The shape and configuration of branched networks influence ecological patterns and processes. Recent investigations of network influences in riverine ecology stress the need to quantify spatial structure not only in a two-dimensional plane, but also in networks. An initial step in understanding data from stream networks is discerning non-random patterns along the network. On the other...
Authors
L.M. Ganio, C.E. Torgersen, R. E. Gresswell
Describing spatial pattern in stream networks: A practical approach Describing spatial pattern in stream networks: A practical approach
The shape and configuration of branched networks influence ecological patterns and processes. Recent investigations of network influences in riverine ecology stress the need to quantify spatial structure not only in a two-dimensional plane, but also in networks. An initial step in understanding data from stream networks is discerning non-random patterns along the network. On the other...
Authors
L.M. Ganio, C.E. Torgersen, R. E. Gresswell
Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales
1. Spatial patterns in channel morphology and substratum composition at small (1–10 metres) and large scales (1–10 kilometres) were analysed to determine the influence of habitat heterogeneity on the distribution and abundance of larval lamprey. 2. We used a nested sampling design and multiple logistic regression to evaluate spatial heterogeneity in the abundance of larval Pacific...
Authors
Christian E. Torgersen, David Close
Pattern detection in stream networks: Quantifying spatial variability in fish distribution Pattern detection in stream networks: Quantifying spatial variability in fish distribution
Biological and physical properties of rivers and streams are inherently difficult to sample and visualize at the resolution and extent necessary to detect fine-scale distributional patterns over large areas. Satellite imagery and broad-scale fish survey methods are effective for quantifying spatial variability in biological and physical variables over a range of scales in marine...
Authors
Christian Torgersen, Robert Gresswell, Douglas Bateman
Non-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.
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.