Evaluating Strategies
for Increasing Plant Diversity
in Crested Wheatgrass Seedings
[Elko County, NV]
Kent McAdoo, Univ. Nevada Coop. Extension
John Swanson, Univ. Nevada Reno
Nancy Shaw, USFS
“Assisted Succession”
(Cox and Anderson 2004)
Restoration of weed-threatened areas
through rehabilitation,
then diversification
Challenge/Opportunity:
Enhancing Diversity
for Wildlife
Crested Wheatgrass Seedings
With 10% Successional Sage Cover
(18 - 28 yr after shrub control & seeding)
• 48% Sagebrush Obligate Birds
• 52% Grass-nesting Birds
(McAdoo et al. 1989 J. Wildlife Manage.)
Research Objectives
1 - Determine the effect of crested wheatgrass
(Aropyron cristatum [L.] Gaertner ) control
methods on wheatgrass density and cover.
2 - Determine the effect of crested wheatgrass
control methods and revegetation on
establishment of seeded species.
Great Basin Native Plant
Selection & Increase Project
Companion studies in:
• Utah
• Oregon
• Idaho
• Nevada
Crested Wheatgrass Control
and Revegetation Treatments
Each study site/trial was comprised of five
5-acre blocks, using a randomized block,
split-split plot design. Each 1-acre
treatment plot was divided into seeded
and unseeded sub-plots.
Treatment Chronology
Trial 1
• Nov. 2007 - “disked only plots” 3-way disked
• May 2008 - “spring-applied herbicide plots”
and “combined disked and herbicide plots”
sprayed with 64 oz. glyph./ac
• Early Oct. 2008 - “combined spring- and fallapplied herbicide plots” sprayed with 64 oz.
glyph./ac
• Late Oct. 2008 - sub-plots seeded by NRCS
Aberdeen PMC team with Truax RR drill
Trial 2
• May 2010 – 4 herbicide treatments applied to
5 new plot blocks
• Late Oct. 2010 – new sub-plots seeded by
NRCS Aberdeen PMC team with Truax RR drill
Seeding mix* for South Fork study plots, Elko
County, NV, in sandy loam soil (Orovada Puett
association), 8–10” precipitation zone.
Species
PLS lb/ac
• Indian ricegrass (‘Nezpar’)
2.0
2.0
• Bottlebrush squirreltail (Toe Jam Cr.)
2.0
• Needle-and-thread grass
2.0
• Basin wildrye (‘Magnar’)
1.0
• Bluebunch wheatgrass (‘Secar’)
0.75
• Sandberg bluegrass
0.5
• Munro globemallow
0.75
• Lewis flax (‘Appar’)
0.2
• Western yarrow
0.2
• Wyoming big sagebrush
0.5
• Spiny hopsage
11.9
Total
________________________________
*Based on ecological site description
Data Collection
• For crested wheatgrass, we estimated
herbaceous cover, density, and seedling
frequency in ten 0.25 m2 quadrats placed
randomly on each of 5 transects and
perpendicular to each transect
• Density for seeded native species was
measured within these same quadrats
• For Trial 1, data was collected during 1st,
2nd, 3rd, and 5th years after seeding
• For Trial 2, data was collected during 2nd
and 3rd years after seeding
Preliminary Results
Trial 1
Untreated
Spring Spray
Spray 2X (spring & fall)
Glyphosate Treatments
Reduced
Crested Wheatgrass
(P<0.05)
Disk + Glyphosate
Crested Wheatgrass Reduction (p<0.05)
Disk Treatment
No Significant CW Reduction (p>0.05)
Crested Wheatgrass Cover (2009)*
% Cover
a
a
24.0
Untreated
20.5
Disk
b
b
b
3.0
2.2
2.2
Spring Glyphosate Spring & Fall Glyphosate Disk & Glyphosate
* means with differing letters are significantly different (p<0.05)
Crested Wheatgrass Cover (2010)*
16
a
14
a
% Cover
12
10
8
b
6
b
b
4
2
0
Untreated
Disk
Spring
Spring & Fall
Disk &
Glyphosate Glyphosate Glyphosate
*Means with differing letters are significantly different (p<0.05)
% Cover
Crested Wheatgrass Cover (2013)*
20
18
16
14
12
10
8
6
4
2
0
a
a
bd
cd
c
Untreated
Disk
Spring
Spring & Fall
Disk &
Glyphosate Glyphosate Glyphosate
*Means with differing letters are significantly different (p<0.05)
Crested Wheatgrass Density (2009)*
b
Plants/m2
a
6.1
c
4.7
c
c
2.9
2.5
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
2.8
Disk & Glyphosate
* Means with differing letters are significantly different (p<0.05)
Crested Wheatgrass Density (2010)*
a
12
a
Plants/m2
10
b
8
b
b
6
4
2
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
Crested Wheatgrass Density (2013)*
8
a
bc
c
7
ac
Plants/m2
6
a
5
4
3
2
1
0
Untreated
Disk
Spring
Spring & Fall
Disk &
Glyphosate Glyphosate Glyphosate
*Means with differing letters are significantly different (p<0.05)
Seeded Species Establishment
First Growing Season
[Precipitation = 119% of normal]
9 of 11 Seeded Species Established
,
Density of Seeded Native Grasses (2010)*
c
Plants/10 m2
12
bc
bc
10
8
ab
6
a
4
2
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
Seeded Forb Densities (2010)*
b
bc
5
Plants/10 m2
4
ab
3
2
a
a
1
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
Density of All Seeded Species (2010)*
C
18
bc
Plants/10 m2
16
c
14
12
10
b
8
6
a
4
2
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
Third Growing Season (2011)
Good, Bad, & Ugly
Ongoing
Study
Good
Additional
plots Species Persistence)
(Seeded
• We established additional plots in 2010
Treatments
• Panoramic
• Landmark
• Round-up (full rate)
• Round-up(half-rate)
• Untreated
Bad
(Crested Wheatgrass Recovery)
Ugly
(Mustard Invasion)
Density (no./10 m2) of seeded native plants
among Agcr treatments by year
Year
Vegetation
Treatment
2009
2010
2011
2013
Spring glyphosate
61.1a
13.4ac
7.2bc
2.0d
Spring + fall
glyphosate
60.5a
13.6b
7.8c
2.0d
Disk + glyphosate
47.4a
18.7b
10.3b
3.0c
Disk
82.4a
5.5b
0.3c
0.7c
Untreated
47.0a
1.8b
0.5b
0.2b
Means with differing letters within the same row (treatment) are
significantly different at p<0.05.
Density (no./10 m2) of seeded native plants
among years by Agcr treatment
Year
Vegetation
Treatment
2009
2010
2011
2013
Spring
glyphosate
61.1a
13.4ab
7.2a
2.0a
Spring + fall
glyphosate
60.5a
13.6a
7.8a
2.0abc
Disk + glyphosate
47.4a
18.7a
10.3a
3.0a
Disk
82.4a
5.5b
0.3b
0.7bd
Untreated
47.0a
1.8c
0.5b
0.2cd
Means with differing letters within the same column (year) are
significantly different at p<0.05.
Challenges
Jackrabbit Impacts?
McAdoo et al. 1987. Use of new rangeland seedings by
black-tailed jackrabbits. J. Range Manage. 40:520-524.
Waste-Cutting by Jackrabbits
Summary – Trial 1
• Effectiveness of all control treatments for
Agcr diminished significantly with 5 years
• Disking increased Agcr density in 1st year
• Seeded native grasses and forbs had high
emergence first growing season, but
diminished significantly within 5 years
• Reducing Agcr competition opened door for
weed invasion
Site, Competition, and Plant Stock Influence
Transplant Success of Wyoming Big
Sagebrush - 2013 Rangeland Ecol. & Manage. 66:305-311
Kent McAdoo, UNR
Chad Boyd, USDA - ARS
Roger Sheley, USDA-ARS
a
Density/10m2
4
A
3
b
b
2
1
Density/10m2
0
4
B
3
a
2
a
1
b
0
Ch
s
ras
g
t
ea
Na
tive
d
ste
e
r
C
Wh
s
ras
g
t
ea
Survival density for transplanted sagebrush as
a function of site for plots planted in spring of
2009 (A) or 2010 (B).
Trial 2 – Treated/Planted 2010
• Precipitation = 82% of long-term mean
• Imazapic and chlorsulfuron +
sulfometuron methyl were ineffective
at suppressing Agcr (p<0.05)
• Only glyphosate treatments resulted in
Agde reduction
• Seeded species failure
Still to Be Determined:
How can we effectively
suppress Agcr competition to
enhance diversification?
Questions?