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
Invasion of Siberian elm (Ulmus pumila) along the South Platte River: The roles of seed source, human influence, and river geomorphology
Riverine complexity and life history inform restoration in riparian environments in the southwestern U.S.
The Transformation of dryland rivers: The future of introduced tamarisk in the U.S.
Vegetation of the Elwha River Estuary
Vegetation of the Elwha River Estuary - Chapter 8
A case for stream corridor restoration
Quantifying and securing environmental flow
Stream-corridor restoration: Some assembly required
Ecological interfaces between land and flowing water: Themes and trends in riparian research and management
Riparian plant communities remain stable in response to a second cycle of Tamarix biocontrol defoliation
Flow‐ecology modelling to inform reservoir releases for riparian restoration and management
Combined effects of biological control of an invasive shrub and fluvial processes on riparian vegetation dynamics
Pre-USGS Publications
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
Large-scale streamflow experiments
Riparian Vegetation Response to Dam Removal
Science to Inform Riparian Ecosystem Restoration and Management
Biological Invasions of Riparian Ecosystems
Streamflow-fluvial Geomorphology-riparian Vegetation Interactions
Ecological Flows
Dam removal: synthesis of ecological and physical responses
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 vegetation, topography, and ground cover constituents along the Upper Colorado River near Moab, UT (2010-2017)
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
Spatial data sets to support conservation planning along the Colorado River in Utah
Spatial datasets to support analysis of the influence of tributary junctions on patterns of fluvial features and riparian vegetation along the Colorado and Dolores Rivers (Utah and Colorado).
Geomorphic, climate, streamflow and vegetation data sets to reconstruct channel and vegetation changes associated with the invasion of Russian olive along the Escalante River, Utah 1950-2015.
Woody riparian invasive plant presence, stem density, and rank dominance and environmental conditions in 2012 at 238 bridge crossings in the Colorado Headwaters, upper/middle Rio Grande, upper Arkansas, and South Platte River Basins, USA
Science and Products
- Publications
Filter Total Items: 111
Invasion of Siberian elm (Ulmus pumila) along the South Platte River: The roles of seed source, human influence, and river geomorphology
Riparian ecosystems in the western USA have been invaded by non-native woody species deliberately introduced for stream bank stabilization, agricultural windbreaks, and urban shade. Recent work suggests that the non-native tree Ulmus pumila (Siberian elm) is capable of significant spread in western riparian ecosystems, that range infilling is still incomplete, and that the invasion is dispersal-liRiverine complexity and life history inform restoration in riparian environments in the southwestern U.S.
Riparian habitat in the southwestern USA has undergone substantial degradation over the past century, prompting extensive management and restoration of these critical ecosystems. Most restoration efforts, however, do not account for life history traits or riverine complexity that may influence genetic diversity and structure. Here, we use simple sequence repeat (SSR) markers in four southwestern rThe Transformation of dryland rivers: The future of introduced tamarisk in the U.S.
Tamarix spp. (tamarisk or saltcedar), a shrub-like tree, was intentionally introduced to the U.S. from Asia in the mid-1800s. Tamarisk thrives in today’s human-altered streamside (riparian) habitats and can be found along wetlands, rivers, lakes, and streams across the western U.S. In 2001, a biological control agent, Diorhabda spp. (tamarisk leaf beetle), was released in six states, and has sinceVegetation of the Elwha River Estuary
The Elwha River estuary supports one of the most diverse coastal wetland complexes yet described in the Salish Sea region, in terms of vegetation types and plant species richness. Using a combination of aerial imagery and vegetation plot sampling, we identified 6 primary vegetation types and 121 plant species in a 39.7 ha area. Most of the estuary is dominated by woody vegetation types, with mixedVegetation of the Elwha River Estuary - Chapter 8
The Elwha River estuary supports one of the most diverse coastal wetland complexes yet described in the Salish Sea region, in terms of vegetation types and plant species richness. Using a combination of aerial imagery and vegetation plot sampling, we identified 6 primary vegetation types and 121 plant species in a 39.7 ha area. Most of the estuary is dominated by woody vegetation types, with mixedA case for stream corridor restoration
No abstract available.Quantifying and securing environmental flow
No abstract available.Stream-corridor restoration: Some assembly required
No abstract available.Ecological interfaces between land and flowing water: Themes and trends in riparian research and management
This paper provides an overview of past, present and future themes for research and management of riparian zones, often relating to papers within this Wetlands Special Feature. Riparian research expanded in the United States around 1980 with themes that recognized (1) damage from excessive livestock, or (2) damage from river damming and diversion, and (3) the beneficial capacity of riparian bufferRiparian plant communities remain stable in response to a second cycle of Tamarix biocontrol defoliation
Reduced abundance of non-native Tamarix shrubs in western U.S. riparian systems following biological control by a defoliating beetle has led to concerns that replacement plant communities could be dominated by other invasive species and/or not provide some of the ecosystem services that Tamarix was providing. In previous studies, Tamarix decline following biocontrol was accompanied by small increaFlow‐ecology modelling to inform reservoir releases for riparian restoration and management
Linked hydrologic, hydraulic, and ecological models can facilitate planning and implementing water releases from reservoirs to achieve ecological objectives along rivers. We applied a flow‐ecology model, the Ecosystem Functions Model (HEC‐EFM), to the Bill Williams River in southwestern USA to estimate areas suitable for recruitment of riparian tree seedlings in the context of managing flow releasCombined effects of biological control of an invasive shrub and fluvial processes on riparian vegetation dynamics
Plant community responses to biocontrol of invasive plants are understudied, despite the strong influence of the composition of replacement vegetation on ecosystem functions and services. We studied the vegetation response to a folivore beetle (Diorhabda genus, Coleoptera) that has been introduced along southwestern US river valleys to control the invasion of non-native shrubs in the genus TamarixPre-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. - Science
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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...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...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.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
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Vascular 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 vegetation, topography, and ground cover constituents along the Upper Colorado River near Moab, UT (2010-2017)
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 (Spatial data sets to support conservation planning along the Colorado River in Utah
With the help of local and regional natural resource professionals, we developed a broad-scale, spatially-explicit assessment of 146 miles (~20,000 acres) of the Colorado River mainstem in Grand and San Juan Counties, Utah that can be used to support conservation planning and riparian restoration prioritization. For the assessment we: 1) acquired, modified or created spatial datasets of Colorado RSpatial datasets to support analysis of the influence of tributary junctions on patterns of fluvial features and riparian vegetation along the Colorado and Dolores Rivers (Utah and Colorado).
To examine potential influence of tributaries on riparian habitat complexity along ~216 km of the Colorado River in Utah and ~300km of the Dolores River in Colorado and Utah, we first classified fluvial features and land cover of the bottomland on remotely sensed imagery. We then examined riparian and geomorphic patterns within the near channel zone with variably-sized spatial units. We used superGeomorphic, climate, streamflow and vegetation data sets to reconstruct channel and vegetation changes associated with the invasion of Russian olive along the Escalante River, Utah 1950-2015.
We analyzed historical aerial photography and used dendrochronology to quantify long-term spatial and temporal patterns of narrowing and vegetation expansion, including native cottonwood (Populus fremontii) and non-native Russian olive (Elaeagnus angustifolia), along the largely unregulated Escalante River in Utah, USA. Our general study area was between the town of Escalante and Choprock Canyon,Woody riparian invasive plant presence, stem density, and rank dominance and environmental conditions in 2012 at 238 bridge crossings in the Colorado Headwaters, upper/middle Rio Grande, upper Arkansas, and South Platte River Basins, USA
This dataset presents observations and measurements of riparian plant invasion, community composition, and environmental conditions at 238 bridge crossings in four western USA river basins: the Colorado Headwaters, upper/middle Rio Grande, upper Arkansas River, and South Platte River (281,946 square kilometers). The 238 sites are a stratified random sample of all bridge crossings in the river basi