Evaluating Strategies
for Increasing Plant Diversity
in Crested Wheatgrass Seedings
[Elko County, NV]
Kent McAdoo, UNCE
John Swanson, UNR
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% Sage Obligate Birds
52% Grass-nesting Birds
(McAdoo et al. 1989 J. Wildlife Manage.)
Research Objectives
1 - Determine the effect of crested wheatgrass
(Aropyron desertorum) 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
•
•
•
•
•
Disking
Spring-applied glyphosate
Disking + spring-applied glyphosate
Spring- + fall-applied glyphosate
Untreated
The study site is comprised of five 5-acre
blocks, using a randomized block, splitsplit plot design. Each 1-acre treatment
plot was divided into seeded and
unseeded sub-plots.
Treatment Chronology
• 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
• 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), approximately 8” precipitation zone.
Species
PLS lb/ac
• Indian ricegrass
2.0
• Bottlebrush squirreltail
2.0
• Needle-and-thread grass
2.0
• Basin wildrye
2.0
• Bluebunch wheatgrass
1.0
• Sandberg bluegrass
0.75
• Munro globemallow
0.5
• Lewis flax
0.75
• Western yarrow
0.2
• Wyoming big sagebrush
0.2
• Spiny hopsage
0.5
Total
11.9
________________________________
*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 belt transect
• Density for seeded native species was
measured within these same quadrats
Preliminary Results
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 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)*
12
a
a
10.6
10.5
Plants/m2
10
8
b
b
b
4.9
4.7
6
5.7
4
2
Untreated
Disk
Spring Glyphosate
Spring & Fall
Glyphosate
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
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)
Seeded Species Establishment
First Growing Season
,
Density of Seeded Native Grasses (2010)*
c
12
bc
bc
Plants/m2
10
11.5
9.6
8
ab
8.3
6
4
a
0.6
4.8
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
4.6
4.8
Spring & Fall
Glyphosate
Disk & Glyphosate
5
Plants/m2
4
ab
3
2
a
a
2.4
0.3
1
Untreated
Disk
Spring Glyphosate
*Means with differing letters are significantly different (p<0.05)
Density of All Seeded Species (2010)*
c
18
Plants/m2
16
14
12
10
bc
c
13.4
13.6
Spring Glyphosate
Spring & Fall
Glyphosate
16.5
b
8
6
4
a
1.4
5.1
2
Untreated
Disk
*Means with differing letters are significantly different (p<0.05)
Disk & Glyphosate
Third Growing Season
– 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)
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
Ongoing Study
Additional plots
• Established in 2010 (spring spray, fall seeding)
Treatments
• Panoramic 2SL (imazapic)
• Landmark XP (chlorsulfuron + sulfometuron methyl)
• Round-up (glyphosate) full rate
• Round-up (glyphosate) half-rate
• Untreated
…Stay Tuned
Great Basin Native Plant
Selection & Increase Project