Native seedlings along the Colorado River consisting of a mix of mostly Baccharis, tamarisk, and a couple of cottonwoods.A peso coin is included for scale.
Patrick Shafroth, PhD
Patrick B. Shafroth is a Research Ecologist at the Fort Collins Science Center.
Since 1991, Dr. Shafroth has conducted research on riparian ecosystems, primarily in arid and semi-arid regions of western U.S. He and his colleagues from the USGS and other institutions have focused their work on understanding relationships between surface and ground-water hydrology, fluvial processes, and the dynamics of native and introduced riparian vegetation. This research has often been conducted in the applied context of riparian ecosystem restoration with the goal of providing solid, objective scientific information that can be used to inform riparian restoration efforts. More specific restoration-related research areas include studies of large-scale flow experiments, dam removal, effects of invasive species control and associated restoration actions, and potential interactions with climate change.
Some of Dr. Shafroth’s current research includes studies of: vegetation and geomorphic responses to experimental flow releases downstream of dams on the Bill Williams River, Arizona; the Colorado River delta in Mexico and the U.S.; and the the Colorado River in Grand Canyon; vegetation and geomorphic responses to dam removal on the Elwha River, Washington, where the world's largest dam removals occurred recently; dynamics of non-native riparian plants along western rivers, including patterns of riparian vegetation recovery associated with biological control of Tamarix.
Education and Certifications
Ph.D. in Plant Biology, Arizona State University, 1999
M.S. in Forest Ecology, Colorado State University, 1993
B.A. in Environmental Studies and Geography, University of California, Santa Barbara, 1989
Science and Products
USGS science supporting the Elwha River Restoration Project
Ecological Drought in Riparian Ecosystems
Ecology and Management of Invasive Riparian Plants
Erosion and Invasive Saltcedar
Riparian Ecology
Science to Inform Riparian Ecosystem Restoration and Management
Large-scale streamflow experiments
Riparian Vegetation Response to Dam Removal
Biological Invasions of Riparian Ecosystems
Streamflow-fluvial Geomorphology-riparian Vegetation Interactions
Ecological Flows
Dam removal: synthesis of ecological and physical responses
Vegetation and geomorphic surfaces in the Elwha River delta, Washington, after dam removal, derived from 2016 and 2018 aerial imagery and 2007, 2014, and 2018 field surveys
Occurrence data and models for woody riparian native and invasive plant species in the conterminous western USA
Occurrence of plants in plots along the Gunnison River, Colorado, 1990-2017
Vascular plant diversity and associated environmental variables along the Elwha River, Washington, 2005-2017
Colorado River Delta Project: A compilation of vegetation indices, phenology assessment metrics, and estimates of evapotranspiration for circular bird plots in the Colorado River delta between 2000-2020 (ver. 1.0)
Southwestern Riparian Plant Trait Matrix, Colorado River, Grand Canyon, Arizona (ver. 2.0, 2022)
Riparian woody stem densities and landscape variables along the South Platte River, Colorado, United States, 2011-2016
Riparian vegetation, topography, and ground cover constituents along the Upper Colorado River near Moab, UT (2010-2017) (ver. 1.1, Jan 2023)
Ecological parameters in the Elwha River estuary before and during dam removal (ver. 2.0, August 2020)
Riparian vegetation, topography, sediment quality and river corridor geomorphology in the Lower Virgin River 2010-2017
Riparian seed dispersal phenology and snowmelt streamflow timing in the upper South Platte River Basin, observed in 2010-2011 and simulated for 1962-2098
Riparian vegetation, topography, sediment quality, and river corridor geomorphology in the Lower Virgin River, Nevada and Arizona, before (2010) and after (2011-2012) a 40-year return period flood
Native seedlings along the Colorado River consisting of a mix of mostly Baccharis, tamarisk, and a couple of cottonwoods.A peso coin is included for scale.
Integrating social-ecological outcomes into invasive species management: The Tamarix case
Outcomes of control and monitoring of a widespread riparian invader (Tamarix spp.): A comparison of synthesis approaches
Vegetation responses to large dam removal on the Elwha River, Washington, USA
Strategic restoration planning for land birds in the Colorado River Delta, Mexico
A review of natural and managed revegetation responses in two de-watered reservoirs after large dam removals on the Elwha River, Washington, USA
Coastal vegetation responses to large dam removal on the Elwha River
Lessons learned from community and citizen science monitoring projects on the Elwha River Restoration Project
Community and citizen science on the Elwha River: Past, present, and future
Functional stability of vegetation following biocontrol of an invasive riparian shrub
Models combining multiple scales of inference capture hydrologic and climatic drivers of riparian tree distributions
Provenance, genotype, and flooding influence growth and resource acquisition characteristics in a clonal, riparian shrub
Does large dam removal restore downstream riparian vegetation diversity? Testing predictions on the Elwha River, Washington, USA
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.
Science and Products
- Science
Filter Total Items: 14
USGS science supporting the Elwha River Restoration Project
The Elwha River Restoration Project has reconnected the water, salmon, and sediment of a pristine river and coast of the Olympic Peninsula of Washington.Ecological Drought in Riparian Ecosystems
Drought is killing riparian trees along many rivers in the western United States. The cause can be increasing temperature or decreasing precipitation, flow or water-table elevation. At multiple locations we are relating water availability to physiological measurements of tree survival and water stress, such as ring width, carbon stable isotope ratio and branch hydraulic conductivity. These...Ecology and Management of Invasive Riparian Plants
Due to high rates of disturbance and human activity, streamside or “riparian” areas are prone to colonization and spread of invasive plants. In the western United States, hundreds of thousands of riparian acres are occupied by the invasive shrubs/trees tamarisk and Russian olive, as well as numerous exotic herbaceous plants. Our work focuses on understanding the factors driving the distribution...Erosion and Invasive Saltcedar
Formation of arroyos in the late 1800s greatly increased erosion across the southwestern United States. Since the 1930s, however, this erosion has decreased, partly because of bank stabilization by introduced saltcedar. With Isleta Pueblo Indian Nation, the Aquatic Systems Branch developed a new sediment dating method using saltcedar tree rings. We applied the method in a landmark study of arroyo...Riparian Ecology
Riparian ecologists at the Fort Collins Science Center study interactions among flow, channel change, and vegetation along rivers across the western United States and worldwide. Our work focuses on issues relevant to the management of water and public lands, including dam operation, climate change, invasive species, and ecological restoration. Investigations take place on a range of scales. For...Science to Inform Riparian Ecosystem Restoration and Management
Throughout the world, riparian habitats have been dramatically modified from their natural condition. Dams, non-native species and climate change are often principal drivers of these changes, via their alteration of water and sediment regimes that determine key resources for riparian plants.Large-scale streamflow experiments
Because the underlying cause of riparian system alteration is often attributed to the effects of dams on flow regime, managing flow releases, particularly high flows, from dams is an often-advocated approach to river and riparian restoration. Our work has focused on understanding effects of managed high flow releases (a.k.a., pulse flows, controlled floods) from dams along rivers in the lower...Riparian Vegetation Response to Dam Removal
Dam removal is an approach to river restoration that is becoming increasingly common. In most cases, dam removal is driven by considerations other than river restoration like dam safety, but how dam removal affects aquatic and riparian systems is of great interest in many dam removals. My work in this area has had two areas of focus thus far: 1) studies of vegetation and geomorphic change...Biological Invasions of Riparian Ecosystems
Beginning in the early twentieth century, non-native trees and shrubs, including tamarisk (also commonly known as saltcedar) and Russian-olive, were introduced to the United States for use as ornamental plants and in erosion-control plantings. These plants spread extensively, becoming the third and fourth most frequently occurring woody riparian plants in the American West.Streamflow-fluvial Geomorphology-riparian Vegetation Interactions
The foundation for applying science to river and riparian restoration contexts lies in a basic understanding of the factors that drive riparian vegetation dynamics. Much of our research is focused on clarifying relationships between streamflow, fluvial geomorphology, and riparian vegetation, including various feedbacks.Ecological Flows
Ecological flow is a central theme of AS Branch studies, as our research examines how water flows affect populations, communities, ecosystems, and hydroscapes. Our studies elucidate the interactions among hydrologic, geomorphologic, biogeochemical, biological, and anthropogenic processes. Branch scientists identify and quantify the spatial and temporal attributes of water flow for ecological needs...Dam removal: synthesis of ecological and physical responses
Dam decommissioning is rapidly emerging as an important river restoration strategy in the U.S., with several major removals recently completed or in progress. But few studies have evaluated the far-reaching consequences of these significant environmental perturbations, especially those resulting from removals of large (>10-15 m tall) structures during the last decade. In particular, interactions b - Data
Filter Total Items: 18
Vegetation and geomorphic surfaces in the Elwha River delta, Washington, after dam removal, derived from 2016 and 2018 aerial imagery and 2007, 2014, and 2018 field surveys
Removal of two large dams from the Elwha River, Washington USA, in 2011-2014 released ~20.5 metric tons (Mt) of impounded sediment, ~5.4 Mt of which was deposited in the river delta and estuary. This dataset presents measurements of geomorphic surfaces, vegetation colonization, and plant community development in the Elwha River delta and estuary after dam removal. Geomorphic surfaces and vegetatioOccurrence data and models for woody riparian native and invasive plant species in the conterminous western USA
We developed habitat suitability models for occurrence of three invasive riparian woody plant taxa of concern to Department of Interior land management agencies, as well as for three dominant native riparian woody taxa. Study taxa were non-native tamarisk (saltcedar; Tamarix ramosissima, Tamarix chinensis), Russian olive (Elaeagnus angustifolia) and Siberian elm (Ulmus pumila) and native plains/FrOccurrence of plants in plots along the Gunnison River, Colorado, 1990-2017
In 1990 the US Geological Survey Fort Collins Science Center and National Park Service Water Resources Division established 133 permanent 1meter (m) X 2 m plots along the Gunnison River near Warner Point in Black Canyon of the Gunnison National Park. A one-dimensional hydraulic model was calibrated to determine the inundation necessary to inundate each plot, and this can be combined with daily floVascular plant diversity and associated environmental variables along the Elwha River, Washington, 2005-2017
The data release presents observations of riparian vegetation, topography, soil characteristics, and ground cover in three river segments located above, below, and between the former Glines Canyon and Elwha Dams on the Elwha River, near Port Angeles, WA (river kilometers 2.5 to 31) to assess effects of dam removal on riparian vegetation. Vegetation data were collected before dam removal in 2005 anColorado River Delta Project: A compilation of vegetation indices, phenology assessment metrics, and estimates of evapotranspiration for circular bird plots in the Colorado River delta between 2000-2020 (ver. 1.0)
These data were compiled to understand the effects of riparian vegetation health on local abundance and species diversity of land birds. The primary objective of our study was to to determine the effects of riparian restoration on birds in the Colorado River delta. These tabular data represent vegetation indices and evapotranspiration (ET) data at varying spatial scales that correspond to avian usSouthwestern Riparian Plant Trait Matrix, Colorado River, Grand Canyon, Arizona (ver. 2.0, 2022)
Trait-based approaches to vegetation analyses are becoming more prevalent in studies of riparian vegetation dynamics, including responses to flow regulation, groundwater pumping, and climate change. These analyses require species trait data compiled from the literature and floras or original field measurements. Gathering such data makes trait-based research time intensive at best and impracticableRiparian woody stem densities and landscape variables along the South Platte River, Colorado, United States, 2011-2016
This data set includes riparian woody stem counts, stem densities and landscape variables collected at 28 sites along the South Platte River, Colorado, United States from 2011-2016. Riparian woody stem densities were collected in the field during 2011, 2015, and 2016, and include the species Ulmus pumila, Populus deltoides, Salix amygdaloides, Fraxinus pennsylvanica, and Elaeagnus angustifolia. FoRiparian vegetation, topography, and ground cover constituents along the Upper Colorado River near Moab, UT (2010-2017) (ver. 1.1, Jan 2023)
The data release presents observations of riparian vegetation, topography, and ground cover in two river reaches of the Upper Colorado River within a river segment extending 208 river kilometers (rkm), from near the Colorado/Utah border to the confluence of the Green River. Methods included field observations and analysis of the plant community five times over eight years in the fall of 2010, 2012Ecological parameters in the Elwha River estuary before and during dam removal (ver. 2.0, August 2020)
The Elwha and Glines Canyon dams were removed from the Elwha River in Washington State from 2011 to 2014. We collected data for a variety of metrics in the estuary and on the river delta before (2006-2011) and during (2012-2014) dam removal to assess how increased sediment transport and deposition affected habitats, vegetation, invertebrates, and fish.Riparian vegetation, topography, sediment quality and river corridor geomorphology in the Lower Virgin River 2010-2017
Plant composition, geomorphic conditions and sediment properties before (2010-2012) and after (2015-2017) the arrival of a biocontrol agent (defoliating beetle in the Diorhabda genus) of invasive Tamarix spp. The data contains four csv files: localization (UTM coordinates of the transects), vegetation and geomorphology, species codes and sediment qualityRiparian seed dispersal phenology and snowmelt streamflow timing in the upper South Platte River Basin, observed in 2010-2011 and simulated for 1962-2098
This dataset presents observations and model projections of climate, riparian cottonwood and willow seed release phenology, snowmelt streamflow timing, and relative timing of seed release and snowmelt peak streamflow in the upper South Platte River Basin, USA. We collected field observations of seed release phenology from three riparian Salicaceae species at 14 riparian sites and used those observRiparian vegetation, topography, sediment quality, and river corridor geomorphology in the Lower Virgin River, Nevada and Arizona, before (2010) and after (2011-2012) a 40-year return period flood
The data release presents observations of riparian vegetation, topography, sediment quality, and river corridor geomorphology in four river reaches of the Lower Virgin River extending downstream 62 river kilometers (rkm) from near the town of Littlefield (AZ) and the Arizona-Nevada border at rkm 119. Methods included field observations and analysis of remotely-sensed data before (2010) and after ( - Multimedia
Water Released Across the U.S. - Mexico Border Brings Life to the Colorado RiverWater Released Across the U.S. - Mexico Border Brings Life to the Colorado River
Native seedlings along the Colorado River consisting of a mix of mostly Baccharis, tamarisk, and a couple of cottonwoods.A peso coin is included for scale.
Native seedlings along the Colorado River consisting of a mix of mostly Baccharis, tamarisk, and a couple of cottonwoods.A peso coin is included for scale.
- Publications
Filter Total Items: 126
Integrating social-ecological outcomes into invasive species management: The Tamarix case
Incorporating societal considerations into decisions related to invasive species management is desirable, but can be challenging because it requires a solid understanding of the ecological functions and socio-cultural and economic benefits and values of the invaded environment before and after invasion. The ecosystem service (ES) concept was designed to facilitate such decision-making by establishAuthorsEduardo Gonzalez-Sargas, Patrick B. Shafroth, Francesc BaroOutcomes of control and monitoring of a widespread riparian invader (Tamarix spp.): A comparison of synthesis approaches
Effective ecological restoration requires empirical assessment to determine outcomes of projects, but conclusions regarding the effects of restoration treatments on the whole ecosystem remain rare. Control of invasive shrubs and trees in the genus Tamarix and associated riparian restoration in the American Southwest has been of interest to scientists and resource managers for decades; dozens of stAuthorsAlexander R.B. Goetz, Eduardo Gonzalez-Sargas, Mayra C. Vidal, Patrick B. Shafroth, Annie L. Henry, Anna A. SherVegetation responses to large dam removal on the Elwha River, Washington, USA
Large dam removal can trigger changes to physical and biological processes that influence vegetation dynamics in former reservoirs, along river corridors downstream of former dams, and at a river’s terminus in deltas and estuaries. We present the first comprehensive review of vegetation response to major fluvial disturbance caused by the world’s largest dam removal. After being in place for nearlyAuthorsPatrick B. Shafroth, Laura G. Perry, James M. Helfield, Joshua Chenoweth, Rebecca L. BrownStrategic restoration planning for land birds in the Colorado River Delta, Mexico
Ecological restoration is an essential strategy for mitigating the current biodiversity crisis, yet restoration actions are costly. We used systematic conservation planning principles to design an approach that prioritizes restoration sites for birds and tested it in a riparian forest restoration program in the Colorado River Delta. Restoration goals were to maximize the abundance and diversity ofAuthorsJoanna Grand, Timothy D Meehan, William V. Deluca, Julia Morton, Jennifer Pitt, Alejandra Calvo-Fonseca, Chris Dodge, Martha Gómez-Sapiens, Eduardo González Sargas, Osvel Hinojosa-Huerta, Pamela L. Nagler, Carlos Restrepo-Giraldo, Patrick B. Shafroth, Stefanny Villagomez-Palma, Chad B WilseyA review of natural and managed revegetation responses in two de-watered reservoirs after large dam removals on the Elwha River, Washington, USA
Large dam removals are increasing in frequency and the response of natural and managed revegetation is a critical consideration for managed restoration of dewatered reservoir landscapes post dam removal. The removal of two large dams on the Elwha River in 2011-2014 provides insight into reservoir revegetation. We review literature and datasets from 2012 through 2018, 1-6 years since reservoir dewaAuthorsJoshua Chenoweth, Patrick B. Shafroth, Rebecca L. Brown, James M. Helfield, Jenise M. Bauman, Sara Cendejas-Zarelli, Chhaya M. Werner, Jarrett L. Schuster, Olivia A. MorganCoastal vegetation responses to large dam removal on the Elwha River
Introduction: Large dam removals provide a restoration opportunity for shrinking coastal wetland habitats. Dam removal can increase sediment delivery to sediment-starved river deltas and estuaries by restoring natural sediment transport and mobilizing reservoir-impounded sediment. However, rapid mobilization of massive quantities of sediment stored behind large dams also constitutes a major ecologAuthorsLaura G. Perry, Patrick B. Shafroth, Samuel J. Alfieri, Ian M. MillerLessons learned from community and citizen science monitoring projects on the Elwha River Restoration Project
Community and citizen science (CCS) projects – initiatives that involve public participation in scientific research – can both sustain and expand long-term monitoring of large dam removal projects. In this article, we discuss our perspectives on CCS associated with the Elwha River dam removals. We summarize how the public has been or could be involved in monitoring and distill lessons learned forAuthorsM. V. Eitzel, Ryan Meyer, Sarah A. Morley, Ian M. Miller, Patrick B. Shafroth, Chelsea Behymer, Christopher Jadallah, David Parks, Anna Kagley, Anne Shaffer, Heidi L. BallardCommunity and citizen science on the Elwha River: Past, present, and future
This report reflects on the past, present, and potential future of community and citizen science (CCS) in the Elwha River watershed, with particular focus on the years before and after a major restoration event: the removal of two dams that had impacted the river system for a century. We ask: how does CCS feature in the Elwha story and how could it feature? We use the term CCS to reference the broAuthorsM. V. Eitzel, Sarah A. Morley, Chelsea Behymer, Ryan Meyer, Anna Kagley, Heidi L. Ballard, Christopher Jadallah, Jeffrey J. Duda, Laurel Jennings, Ian M. Miller, Justin Stapleton, Anne Shaffer, Allyce Miller, Patrick B. Shafroth, Barbara BlackieFunctional stability of vegetation following biocontrol of an invasive riparian shrub
Understanding plant community response to environmental change is a crucial aspect of biological conservation and restoration, but species-based approaches are limited in that they do not reveal the underlying mechanisms driving vegetation dynamics. An understanding of trait-environment relationships is particularly important in the case of invasive species which may alter abiotic conditions and aAuthorsAnnie L. Henry, Eduardo Gonzalez-Sargas, Patrick B. Shafroth, Alexander R.B. Goetz, Anna A. SherModels combining multiple scales of inference capture hydrologic and climatic drivers of riparian tree distributions
Predicting species geographic distributions is key to managing invasive species, conserving biodiversity, and understanding species' environmental requirements. Species distribution models (SDMs) commonly focus on climatic predictors, but other environmental factors can also be essential, particularly for species with specialized habitats defined by hydrologic, topographic, or edaphic conditions (AuthorsLaura G Perry, Catherine S. Jarnevich, Patrick B. ShafrothProvenance, genotype, and flooding influence growth and resource acquisition characteristics in a clonal, riparian shrub
PremiseRiparian plants can exhibit intraspecific phenotypic variability across the landscape related to temperature and flooding gradients. Phenotypes that vary across a climate gradient are often partly genetically determined and may differ in their response to inundation. Changes to inundation patterns across a climate gradient could thus result in site-specific inundation responses. PhenotypicAuthorsEmily C. Palmquist, Kiona Ogle, Thomas G. Whitham, Gerard J. Allan, Patrick B. Shafroth, Bradley J. ButterfieldDoes large dam removal restore downstream riparian vegetation diversity? Testing predictions on the Elwha River, Washington, USA
Large dams and their removal can profoundly affect riparian ecosystems by altering flow and sediment regimes, hydrochory, and landform dynamics, yet few studies have documented these effects on downstream plant communities. Ecological theory and empirical results suggest that by altering disturbance regimes, reducing hydrochory, and shifting communities to later successional stages, dams reduce doAuthorsRebecca L. Brown, Cody C. Thomas, Erin S. Cubley, Aaron J. Clausen, Patrick B. ShafrothNon-USGS Publications**
Shafroth, P.B., J.C. Stromberg, D.T. Patten, A.E. Springer, and J.M. Wright. 1996. Ground-water recharge and riparian habitat enhancement from water discharged from New Waddell Dam into the Agua Fria River: Phase I--Planning and feasibility. Final Report to Arizona Dept. of Water Resources - Phoenix Active Management Area. Phoenix, AZ78+ap p.Shafroth, P.B., J.M. Friedman, and L.S. Ischinger. 1994. River salinity has little influence on establishment of cottonwood and saltcedar. Research Information Bulletin 94-95. NBS Information Bulletin.**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.