Riparian vegetation monitoring 

and research in the Colorado 

River Ecosystem

Brad Butterfield

Merriam-Powell Center for Environmental Research

& Department of Biological Sciences

Northern Arizona University
Project Team

• Ground-based monitoring and research

• Emily Palmquist - GCMRC

• Sarah Sterner - GCMRC

• Barb Ralston - GCMRC

• David Merritt - USFS

• Patrick Shafroth - USFS

• Tom Kolb - NAU

• Miles McCoy-Sulentic - NAU

• Remote-sensing monitoring and research

• Joel Sankey - GCMRC

• Laura Durning - NAU

• Ash Benford - NAU

• Temuulen Sankey - NAU
Project 11, Elements 1-2

• 11.1 – Ground-based vegetation monitoring

• 11.2 – Periodic landscape scale vegetation mapping and analysis using 

remotely sensed data

• Other elements in Project 11

• 11.3 – Influence of sediment and vegetation feedbacks on sandbars

• Resumed in 2018 following loss of Daniel Sarr

• 11.4 – Terrestrial-aquatic linkages

• Poster by Christina Lupoli

• 11.5 – Science review panel of vegetation control

• Covered in previous ARM, OFR published in 2017 (Ralston and Sarr)
Study Objectives

• Monitor status and trends of vegetation, in particular

• Ratio of native-to-nonnative species, including impact of tamarisk beetle

• Plant cover and species diversity

• Variation along different river segments

• Determine vegetation responses to hydrological variation, including

• Composition of vegetation and identification of flow-response guilds

• Underlying drivers of flow-response guilds

• Broad-scale variation in vegetation composition through classification of 

remotely sensed data
Methods – Status & Trends and Modeling

• Ground-based sampling

• Fixed sites – NAU sandbars

• Random sites – sandbars, debris 

fans and channel margins
Methods – Status & Trends and Modeling

• Ground-based sampling

• Fixed sites – NAU sandbars

• Random sites – sandbars, debris 

fans and channel margins

• Remotely-sensed data

• Process and classify 2013 imagery

• Special focus on tamarisk 2009 vs. 

2013
Methods – Status & Trends and Modeling

• Ground-based sampling

• Fixed sites – NAU sandbars

• Random sites – sandbars, debris fans 

and channel margins

• Remotely-sensed data

• Process and classify 2013 imagery

• Special focus on tamarisk 2009 vs. 

2013

• Functional trait measurements

• Influence hydrological responses

• Field measurements (funded by 

WaterSMART) and literature

• Identify flow response guilds
Kanab Creek Confluence at river km 232

2009 2013 Change

Results – Beetle Impacts on Tamarisk

Bedford et al. (2018) Ecological Indicators

Tamarisk Classification 

Beetle-Impacted Tamarisk 
Total Tamarisk 

Area: 214.4 ha

Beetle-Impacted 

Area: 32.1 ha 

(15%)

Results – Beetle Impacts on Tamarisk

Bedford et al. (2018) Ecological Indicators

Beetle-Impacted 

Tamarisk 0/o 

- 1-10 

10 - 20 

- 20-40 

- 40-84 

Overall Accuracy 

In Quads 

c==J <70 4~o 

- 70-79°/o 

c==J 80 - 89°/o 

km from Lees 

• Ferry at Paria 

River Confluence 

Elevation 

- High : 3~840 m 

Low: 312 m 

100 km 

- Colorado River 

- Lake Mead 

- Grand Canyon NP 
Results – Vegetation Responses

• Marble Canyon is more 

floristically rich than rest of 

canyon 

• Segments vary in floristic 

composition and may respond 

differentially to operations

• Climatic variation along river 

influences hydrological 

responses (Butterfield et al., 

In review)

• Please see poster by Sarah 

Sterner for additional results

Variation in Proportional Cover by Plant 

Functional Group

Palmquist et al. 2017 Journal of Arid 

Environments
Results –Traits and Guilds

• Reveal underlying physiological and 

life-history factors that determine plant 

responses to dam operations

• Used to identify 16 flow-response 

guilds (Merritt et al., In prep) from 104 

species

• Flow-response guilds will help to 

simplify modeling responses to dam 

operations

Example of trait response to inundation

McCoy-Sulentic et al. 2017 Wetlands
Results – Remote Sensing Classification

• Please see poster by 

Laura Durning

• Classification results 

overlap nicely with guild 

delineations

• Will facilitate future 

integration between 

remotely-sensed and 

ground-based monitoring 

and modeling

Durning et al., In prep
Results - Integration

• Data and models at varying 

resolution and extent

• Remotely sensed classifications

• Guilds

• Species-specific models e.g. 

• Can tailor analyses to specific 

resource questions

Habitat Suitability

Butterfield et al., Unpublished data

Modeled Habitat Suitability 

for Seepwillow (Baccharis

emoryi) at Buck Farm
Conclusions and Future Research

• Beetle impacts are extensive but highly variable

• Somewhat associated with tributaries

• Future areas of inquiry:

• Genetic variation in susceptibility

• Environmental drivers
Conclusions and Future Research

• Beetle impacts are extensive but highly variable

• Vegetation composition is distinctly different among river segments

• What are the environmental drivers of these differences?

• How does this impact responses to dam operations?
Conclusions and Future Research

• Beetle impacts are extensive but highly variable

• Vegetation composition is distinctly different among river segments

• Physiological tradeoffs underlie responses to hydrological variation

• Closer to mechanistic understanding of vegetation responses

• Planned experiments using external funding to better understand responses 

to hydrology and climate, and underlying genetic basis
Conclusions and Future Research

• Beetle impacts are extensive but highly variable

• Vegetation composition is distinctly different among river segments

• Physiological tradeoffs underlie responses to hydrological variation

• Remotely-sensed classifications align well with flow-response guilds

• This will allow us to extrapolate results from ground-based monitoring to 

broader extents
2017 Publications

• Bedford et al. (2018) Remote sensing of tamarisk beetle (Diorhabda carinulata) impacts along 412 km of the 

Colorado River in the Grand Canyon, Arizona, USA. Ecological Indicators, 89:365-375

• Bedford et al. (2018) Remote sensing derived maps of tamarisk (2009) and beetle impacts (2013) along 412 km of the Colorado River in the Grand Canyon. USGS data release, Arizona, USA, 10.5066/F72B8X71

• Palmquist et al. (2017) Landscape-scale processes influence riparian plant composition along a regulated 

river. Journal of Arid Environments, 148:54-64.

• Palmquist et al. (2017) Functional traits and ecological affinities of riparian plants along the Colorado River in Grand Canyon. Western North American Naturalist, 77:22-30.

• McCoy-Sulentic et al. (2017) Variation in species-level plant functional traits over wetland indicator status 

categories. Ecology and Evolution, doi: 10.1002/ece3.2975.

• McCoy-Sulentic et al. (2017) Change in community-level riparian plant traits over inundation gradients, Colorado River, Grand Canyon. Wetlands, doi: 10.1007/s13157-017-0895-3.

• Ralston and Sarr (2017) Case studies of riparian and watershed restoration in the Southwestern United 

States – principles, challenges, and successes. OFR 2017-1091.

• Ralston et al. (2017) Taxonomic and compositional differences in ground-dwelling arthropods in riparian habitats in Glen Canyon, Arizona, USA. Western North American Naturalist, 77:369-384.