Integrating Weed Control and Restoration

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Integrating Weed Control and Restoration
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The problem Cheatgrass (Bromus tectorum)
invasion in Great Basin rangelands
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Why is cheatgrass so successful?

• Prolific seed production

• High competitive ability

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Changes disturbance regime
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Solution
X
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• Integrating Weed Control and Restoration
  Collaborators

Robert Nowak Hudson Glimp Nancy Markee Barry
Perryman
Gene Schupp Chris Call
Paul Doescher John Tanaka
Jeanne Chambers Robin Tausch
Robert Blank Tom Jones
Dan Ogle Loren St. John
Mike Pellant
David Pyke
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Experiment 1 A transition stage approach

• Plant materials for transition stage
• Bluebunch wheatgrass Anatone, Goldar, P-7, P-12
• Snake River wheatgrass Secar, SERDP
• Basin wildrye Magnar, Trailhead
• Sandberg bluegrass Hanford, High Plains,
• Mountain Home, Sherman
• Thickspike wheatgrass Bannock, Critana
• Squirreltail Sand Hollow, Shaniko Plateau
• Western yarrow Eagle, Great Northern
• Scarlet globemallow
• Siberian wheatgrass Vavilov
• Crested wheatgrass CD-II
• Annual grass hybrids Mountain rye,
• Pioneer, Regreen, Stani
• Note replaced with winterfat, shadscale,
  four-wing saltbush,
• Rimrock indian ricegrass at Nevadas Izzenhood
  Ranch study site

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Experiment 1 A transition stage approach
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Experiment 1 A transition stage approach

• Effects of herbicide treatments
• Reduces cheatgrass

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Experiment 1 A transition stage approach

• Effects of herbicide treatments
• Reduces cheatgrass, but other species increase

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Experiment 1 A transition stage approach

• Effects of herbicide treatments
• Reduces cheatgrass, but other species increase
• Variable for seeded species

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Experiment 1 A transition stage approach

• Success of seeded species Nevada

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Experiment 1 A transition stage approach

• Success of seeded species Nevada

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Experiment 1 A transition stage approach

• Success of seeded species Nevada

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Experiment 1 A transition stage approach

• Success of seeded species All sites
• Best performers (comparable to crested
  wheatgrass)
• Anatone P-12 bluebunch wheatgrass
• SERDP Secar Snake River wheatgrass
• Critana thickspike wheatgrass
• Sherman sandberg bluegrass

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Experiment 2 A plant functional type approach

• Cheatgrass inhibited by low soil nitrogen,
• but natives are tolerant of low nitrogen

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Experiment 2 A plant functional type approach

• Cheatgrass inhibited by low soil nitrogen,
• but natives are tolerant of low nitrogen
• Soil amendments to tie up nitrogen

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Experiment 2 A plant functional type approach

• Cheatgrass inhibited by low soil nitrogen,
• but natives are tolerant of low nitrogen
• Soil amendments to tie up nitrogen (sucrose)
• Mix of natives to deplete resources
• sagebrush evergreen extensive rooting
• High Plains bluegrass earliest shallowest
• Sand Hollow squirreltail early shallow
• Anatone bluebunch wheatgrass mid extensive
• Great Northern yarrow mid surface root mat
• scarlet globemallow early extensive

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Experiment 2 A plant functional type approach
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Specific questions

1. Did sucrose reduce soil N?
2. Did the target species benefit?
3. Did sucrose facilitate establishment?
4. Did cheatgrass reduce native recruitment?
5. Was cheatgrass adversely affected?
6. Did the 6-species mix reduce cheatgrass?
7. Was cheatgrass seed output, biomass, or density
   reduced?

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1. Did sucrose reduce soil N ?

Oct 2003 - Jan 2004
Jan 2004 - March 2004
Micrograms NO3 per day
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Experiment 2 A plant functional type approach

• Success of seeded species

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2.2 Did cheatgrass reduce native recruitment ?

• Target species density second season (NV)
• High precip site species differ (plt0.001)
• Low precip site species differ (plt0.001)
• BRTE by sucrose interaction (p 0.003)

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3.1 Did the 6 species mix reduce cheatgrass?
sugar p 0.02
species p 0.001 species p
0.01
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3.2 Was cheatgrass seed output, biomass or
density reduced?
P 0.005
P 0.0004
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Experiment 2 A plant functional type approach

• Effects of sugar treatments
• Reduces cheatgrass biomass and seed production
• Consistent effect among all sites

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Conclusions

• Did sucrose reduce soil N? YES
• How well did target species establish?
• Did sucrose facilitate establishment? No
• Did cheatgrass alter native recruitment? yes
• Was cheatgrass adversely affected?
• Did the 6-species mix reduce cheatgrass?
• NO
• Was cheatgrass seed output, biomass, or density
  reduced? Sucrose YES, species mix NO effect
  short-lived

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Experiment 3 Large-scale restoration trials
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Experiment 3 Overview

• Application of successful restoration techniques
  from Experiments 1 and 2
• Transition community vs. Native mix
• Restoration treatments targeted at
• reduce cheatgrass seedbank
• reduce available soil N
• Use ecological principles from first 2
  experiments on large, management-scale plots

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Bedell Flats

• BLM allotment primary use was grazing
• Secondary uses include off-road vehicle use and
  target shooting
• Burned in the summer of 2000
• Subsequently seeded by BLM
• Thickspike wheatgrass
• Crested wheatgrass
• Western wheatgrass
• Four-wing saltbrush
• Ladak Alfalfa
• Fenced in April 2005

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Objectives

• Determine the relative success of restoration
  strategies to control cheatgrass competition and
  its prolific seed production.
• Determine whether a transition community of
  competitive natives can be established more
  readily than a diverse community of different
  growth forms

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Experimental Design

• 4 treatments
• 3 replicates per treatment
• 2 seed mixtures

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Treatments

• 4 treatments
• Seed-Burn-Seed
• Sterile winter wheat seeded October 2004
• Burned October 2005
• Seed Only
• Herbicide Seed
• Herbicide treatment April 2005
• Unseeded Control
• Perennial species Seeded in November 2005

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Seedings

• 2 seed mixtures
• Chosen assessions based on performance in
  Experiment 1
• Anatone bluebunch wheatgrass     
• Nezpar Indian ricegrass                
• Sherman big bluegrass                 
• Shaniko Plateau squirreltail           
• Bannock thickspike wheatgrass    
• Magnar basin wildrye         
•              
• Chosen seed mixture based on performance in
  Experiment 2
• Anatone bluebunch wheatgrass       
• High Plains Sandbergs bluegrass       
• Sand Hollow squirreltail                  
• Globe mallow                                
• Eagle yarrow                                
• Wyoming big sagebrush    
•             
• Seeding mixtures were randomly assigned to
  sub- plot a or b (split-plot)

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Response Variables Measured

• Background Plant Community
• Aboveground Biomass
• Plant Density
• Soil Nutrients
• Soil Seedbank

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Results Background Plant Community

• One year following treatment
• Decreases in cheatgrass cover (p0.07) following
  herbicide treatment
• Decrease in shrub cover (p0.07) following burn
  treatment

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Results Background Plant Community

• No significant treatment effect seen for annual
  forb (p0.22), perennial forb (p0.62), or native
  bunchgrass (p0.41) cover

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Results Planted Species Biomass
Treatment p0.34 Seeding
p0.12 Treatment x Seeding p0.23
We saw no incidence of planted shrub or forb
germination in Experiment 2 seeding mixtures
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Results Cheatgrass Biomass
year p0.02 Treatment
p0.31 Seeding p0.42
Exp 1 Seeding
Exp 2 Seeding
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Results Annual Forb Biomass
year p0.01 Treatment
p0.77 Seeding p0.58
Exp 1 Seeding
Exp 2 Seeding
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Results Perennial Biomass

• No treatment effect seen in perennial forb
  (p0.82) or perennial grass (p0.24) biomass one
  year following treatment

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Results Planted Species Density
Treatment p0.003 Seeding
p0.01 Treatment x Seeding p0.08
More germination in Exp 2 seeding plots Higest
number of germinants in herbicide treatments We
saw no incidence of planted shrub or forb
germination in Experiment 2 seeding mixtures
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Results Cheatgrass Density
Treatment p0.07 Seeding
p0.002
Lowest cheatgrass numbers in herbicide-treated
plots Difference in seedings due to planting
(drill seeding vs. drill and broadcast seeding)?
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Results Density

• No treatment effect seen in forb (p0.70) or
  bunchgrass (p0.17) density one year following
  treatment

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Results Soil Nutrients

• Season Effect Higher availability in later
  season
• Early (February April 2006)
• Late (May September 2006)

Ammonium plt0.0001
Nitrate p0.07
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Cheatgrass SeedbankResults
Herbicide treatment significantly reduced
cheatgrass litter (plt0.001) and soil (p0.01)
seedbank in first post-treatment year
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Conclusions

• Weed management is a long-term process!
• Takes time to establish desirable vegetation
• Takes more than one year of treatment to control
  cheatgrass
• So far herbicide application has been the most
  effective method of control
• Reduction of soil N reduced cheatgrass
  productivity, but not practical on large scale
  unless
• Can establish native vegetation to reduce soil
  resources
• Can use another means (mechanical removal,
  burning) to remove N from the system
• Can suppress cheatgrass for gt 1 season

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Acknowledgements

• Funding USDA CREES, NAES, BLM, USGS, USFS
• Field and lab work Laura Blonski, Jeff Burnham,
  Lisa Ellsworth, Jacob Landmesser, Eugenie
  Montblanc, Christo Morris, Kendra Moseley, Scott
  Shaff, Carlos Wilson, and the many volunteers and
  student workers who set up plots and collected
  and processed data.
• Data analysis David Turner, David Board, and
  George Fernandez statistical consultation and
  expert SAS coding skills.