Evaluating Strategies
for Increasing Plant Diversity
in Crested Wheatgrass Seedings
[South Fork Study, Elko County, NV]
Kent McAdoo, UNCE
John Swanson, UNCE
Nancy Shaw, USFS
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.
Crested Wheatgrass Control
and Revegetation Treatments
The following strategies are being tested in a randomized
block, split-split plot design: (1) untreated crested
wheatgrass; (2) partially controlled crested wheatgrass;
and (3) completely controlled crested wheatgrass. The
study site is comprised of 5 blocks.
Within these main plots, the following methods of control
(mechanical and chemical) and revegetated vs. nonrevegetated strategies are being compared:
• Untreated crested wheatgrass plots receiving no
chemical or mechanical treatment, but divided into
unseeded and seeded sub-plots.
Crested Wheatgrass Control
and Revegetation Treatments
• Partially controlled crested wheatgrass plots
split into 3-way disked or herbicide-treated
plots, divided into unseeded and seeded subplots.
• Completely controlled crested wheatgrass
plots split into combined 3-way disked and
herbicide-treated plots or combined spring and
fall herbicide-treated plots, divided into
unseeded and seeded sub-plots.
Study Plot Preparation
During November 2007, “disked only plots”
were 3-way disked. In May, 2008 “springapplied herbicide plots” and “combined
disked and herbicide plots” were sprayed
with 66 oz. glyphosate/ac. In early
October 2008, “combined spring- and fallapplied herbicide plots” were sprayed with
66 oz. glyphosate/ac. Sub-plots targeted
for seeding were seeded in late October
2008 by personnel from the NRCS
Aberdeen Plant Materials Center with a
Truax Rough Rider rangeland drill.
No Treatment
Spray (Spring „08)
No Treatment
Disc (Fall) &
Spray (Spring)
Fall Disk
Spring Spray
Final seeding mix for South Fork study plots, Elko
County, NV, in sandy loam soil (Orovada Puett
association), approximately 8” precipitation zone.
Species
• Indian ricegrass
• Bottlebrush squirreltail
• Needle-and-thread grass
• Basin wildrye
• Bluebunch wheatgrass
• Sandberg bluegrass
• Munro globemallow
• Lewis flax
• Western yarrow
• Wyoming big sagebrush
• Spiny hopsage
Total
PLS pounds
2.0
2.0
2.0
2.0
1.0
0,75
0.5
0.75
0.2
0.2
0.5
11.9
Fall Seeding - 2008
Data Collection – 2009
• In summer 2009, we collected cover and
density data for unseeded and seeded
species. We estimated herbaceous cover
and density in 5- 0.5 m2 quadrats placed
randomly on each of 5 transects and
perpendicular to each belt transect.
Mortality of crested wheatgrass was
determined by comparing density of live
plants on treated vs. untreated plots.
Preliminary Results
No Control & Seed
Disk & Seed
No significant Agde Reduction (p>0.01)
Spray & Seed
Spray 2X (spring & fall)
& Seed
Disk + Spray & Seed
No Control & Seed
Spray 2X (spring & fall)
& Seed
Spray & Seed
2 Treatments That
Reduced Agde (P<0.01)
Disk + Spray & Seed
Disk + Spray & Seed
Disk + Spray & Seed
Seeded Species
Establishment
So Far – So Good
Jackrabbit Depredation
Future Plans
Additional plots
• We will establish additional plots in 2010 for
comparisons between years.
Analysis & Publication
• Data will be analyzed using mixed model
analysis, with blocks and years considered
random and other treatments considered fixed.
• Publish Manuscript