Veg-Sand Feedbacks 

and Updates on

Project C.1 and C.3

Brad Butterfield1 and

Emily Palmquist1,2

1. Northern Arizona University, Center for Ecosystem 

Science and Society (Ecoss)

2. USGS Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center
Project Elements and Objectives

• C.1 Ground-based vegetation monitoring

• Objective: Monitor annual changes to riparian species composition and cover

• C.3 Vegetation responses to LTEMP flow scenarios

• Objective: Develop predictive models of vegetation composition as it relates 

to hydrological regime

• Riparian Vegetation Resource Objectives:

• “Maintain native vegetation and wildlife habitat, in various stages of maturity, 

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

ecologically appropriate.”
How is Vegetation 

Impacting Sediment?
Diehl et al. 2017 Bioscience

Morphological Guilds: Diehl et al. 2017 Bioscience
Hydrological Zones

Butterfield et al., In press, River Research and Applications
Geomorphic 

Position

Separation Zone

Central Zone

Reattachment Zone

Butterfield et al., In press

River Research and Applications
Elevation 

Change (m)

2013-2018

Plant morphological 

guild

Plant guild + 

elevation change

Butterfield et al., In press, River Research and Applications
Vegetation Effects - Expectations

• Expected patterns

• Increase in deposition (positive 

change) with increasing guild 

number (larger, more rigid)

• Consistent interaction with 

geomorphic position

Butterfield et al., In press, River 

Research and Applications
Vegetation Effects - Observed

Butterfield et al., In press, River Research and Applications
Vegetation Effects

• Species effects depended on 

geomorphic position

• Low-statured, rhizomatous species 

captured sediment best in high- velocity areas (separation zone)

• Large shrubs captured sediment in 

low-velocity areas (reattachment 

zone)

• Identifies specific sediment impacts 

based on guild, hydrological zone, 

and geomorphic position that can be 

used to achieve sediment 

management targets 

Butterfield et al., In press, River Research and Applications
Project Element C.1. 

Ground-Based 

Vegetation 

Monitoring

• >20,000 Plots surveyed 

since 2014

• River-system-wide

• NAU sandbars

• 5-year Status and Trends 

forthcoming

• In case you missed 

yesterday’s poster...

Inactive 

Floodplain

Active 

Floodplain

Active 

Channel

Preliminary data, do not cite
Project Element C.3. Vegetation 

Responses to LTEMP Flow Scenarios

• Developed environmental niche models for 

common species

• First used to assess vegetation optima relative to 

current flow regimes

• Beginning to use these 

models to project habitat 

suitability in the future 

under different flow 

scenarios (Kasprak et al.

In prep)

1991 at 51 Mile

Butterfield et al. 2018 AVS
In many locations,

Vegetation is likely to colonize most of the remaining bare sand area

Kasprak et al. In prep Preliminary data, do not cite

(e.g., baccharis, willow,

mesquite)

NATIVE RIPARIAN

SHRUBS

(e.g., brittlebush, creosote,

annual/perennial grasses)

XERIC SHRUBS/GRASSES

(e.g., tamarisk)

NON-NATIVE

RIPARIAN SHRUBS

(e.g., phragmites,

Bermuda grass)

RIPARIAN HERBS
Approaches to Predicting Flow Responses

Manipulative Experiments 

Outside The Canyon

Physiological 

Measurements Inside The 

Canyon

Long-Term Monitoring

(Ground-Based & 

Remotely-Sensed)

Other River Systems & Flow 

Regimes

(“Grand Canyon in Context”)

Bayesian Modeling
Manipulative 

Experiments 

Outside The 

Canyon
Before After

Manipulative Experiments Outside The Canyon, cont.
“Grand Canyon in Context”

• Monitoring data 

from other 

relevant river 

systems

• NCPN

• Big Rivers

• What flow regimes represent 

suitable conditions for species in 

Grand Canyon?

• Harnessing “big data” by merging 

extensive datasets

• Georeferenced herbarium records

• National Hydrography Database

• Climate data

• Is Grand Canyon hot and dry for this 

species? Or cold and wet? How does 

that affect flow response?

Preliminary data, do not cite Butterfield, Palmquist and Hultine In prep
Physiological Measurements Inside The Canyon

• Water isotopes: Which species are using river water, and to what degree?

• Different deuterium signatures in river water versus precipitation-derived moisture

• Can vary with season (Smith et al. 1998 Wetlands) 

• Transpiration and 

photosynthesis

• Seasonal timing 

of activity

• Responses to 

changes in flow

• Seasonal

• Diurnal

• HFEs

Butterfield et al., In press, River Research and Applications
Approaches to Predicting Flow Responses, cont.

Manipulative Experiments 

Outside The Canyon

Physiological 

Measurements Inside The 

Canyon

Long-Term Monitoring

(Ground-Based & 

Remotely-Sensed)

Other River Systems

(“Grand Canyon in 

Context”)

Bayesian Modeling