Photo: E. Palmquist 

Project C: Getting to know Colorado

River riparian plant communities 

Emily Palmquist1 & Brad Butterfield2 

Glen Canyon Dam Adaptive Management Program 

Adaptive Management Work Group Meeting 

28-29 February 2024 

1 U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and Research Center 

2 Department of Biological Sciences, Northern Arizona University 
 

Photo: USGS GCMRC 

Goal 11. Riparian Vegetation. Maintain native vegetation 

and wildlife habitat, in various stages of maturity, such 

that they are diverse, healthy, productive, self-sustaining, 

and ecologically appropriate. 

• What species do we have now? 

• Cover 

• Composition 

• Why do we have those species? 

• Flow patterns 

• Sediment 

• Climate 

• How can we change these patterns? 
 

 

How are we studying plant community 

responses to dam operations? 

• Annual monitoring (C.1) 

• Manipulative experiments (C.2) 

• Synthesis of multiple lines of evidence & predictive modeling (C.3) 

• Management decision support (C.4) 

Photo: USGS GCMRC Photo: E. Palmquist Photo: E. Palmquist Image: B. Butterfield 
Photo: E. Palmquist 

Photo: USGS GCMRC 

 

 

 

 

C.1 Annual monitoring is the 

backbone of plant research 

• Native species cover & richness 

greater than nonnative 

• Where you are matters: some 

species do better with high daily 

flows at night, others during the day! 

• Responses to dam operations 

depend on temperature, which 

increases downstream 

• Amount of sand is almost as strong 

of an environmental driver as water 

availability/inundation 

Palmquist and others, 2023 

Palmquist and others, in review 

Preliminary Information – Subject to Revision. 

Not for Citation or Distribution. 
 

 

 

 

 

 

 

 

 

C.2 Take-homes from 

experiments 

• Inundation tolerance is predictable from 

habitat preferences in the field, but not 

drought tolerance 

• Understudied clonal species (e.g. arrowweed) 

behave much differently than the well-studied 

trees (e.g. cottonwoods) 

• Cottonwoods and tree willows are less 

tolerant of both inundation AND drought than 

common species 

• New for 2023! Daily fluctuation experiment 

suggests there are some differences in plant 

responses to day/night inundation timing 

Palmquist and others, 2022; 

Butterfield and others, 2024; 

Butterfield and Palmquist, in prep 

Preliminary Information – Subject to Revision. 

Not for Citation or Distribution. 

Photos: B. Butterfield 
C3. Predictive modeling 

and synthesis 

• High/low flow seasonality has shaped 

the species composition 

• Species that have expanded in recent 

decades (e.g. Baccharis, arrowweed) 

are predicted to respond positively to 

high summer flows 

• Webtool, SEIS, etc. 

• Response to flow alterations 

• Rapid model prediction for many 

scenarios 

Butterfield and others, 2023; 

Butterfield and Palmquist, in prep 

Image credit: US Bureau of Reclamation From: Butterfield and others, 2023 
Many colleagues, collaborators, boat 

operators, students, and volunteers 

assisted with these projects -

Thank you! 

Photo: USGS GCMRC 

Further questions? 

Contact us: 

epalmquist@usgs.gov 

or Search “Emily Palmquist USGS” 

Bradley.butterfield@nau.edu 

Interested in the riparian vegetation program? 

Check out our websites: 

https://www.usgs.gov/centers/southwest-biologicalscience-center/science/overview-riparian-vegetationgrand-canyon 

https://www.usgs.gov/centers/southwest-biologicalscience-center/science/terrestrial-riparian-vegetationmonitoring-how 

or Search “GCMRC riparian vegetation” 
 

 

 

 

 

 

 

 

 

 

 

References 

Butterfield, B.J., Palmquist, E.C., and Yackulic, C.B., 2023, The hydroclimate niche: A tool for predicting and managing 

riparian plant community responses to streamflow seasonality: River Research and Applications, v. 39, no. 1, p. 84-94, 

https://doi.org/10.1002/rra.4067 

Butterfield, B.J., and Palmquist, E.C., 2024, Inundation Tolerance, Rather than Drought Tolerance, Predicts Riparian Plant 

Distributions Along a Local Hydrologic Gradient: Wetlands, v. 44, no. 1, p. 6, https://doi.org/10.1007/s13157-023-01730-

2. 

Butterfield, B.J., and Palmquist, E.C., in prep, Timing of daily water fluctuations influences riparian plant root growth and 

water stress. 

Palmquist, E.C., Butterfield, B.J., and Ralston, B.E., 2023, Assessment of riparian vegetation patterns and change 

downstream from Glen Canyon Dam from 2014 to 2019: U.S. Geological Survey Open-File Report 2023–1026, 55 p., 

https://doi.org/10.3133/ofr20231026. 

Palmquist, E.C., Ogle, K., Whitham, T.G., Allan, G.J., Shafroth, P.B., and Butterfield, B.J., 2022, Provenance, genotype, and 

flooding influence growth and resource acquisition characteristics in a clonal, riparian shrub: American Journal of Botany, 

v. 110, no. 2, p. e16115, https://bsapubs.onlinelibrary.wiley.com/doi/abs/10.1002/ajb2.16115 

Palmquist, E.C., Ogle, K., Butterfield, B.J., Whitham, T.G., Allan, G.J., and Shafroth, P.B., in review, Hotter temperatures alter 

riparian plant outcomes under regulated river conditions: Ecological Monographs.