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Cheatgrass Die-Offs: A Unique Restoration Opportunity in Northern Nevada

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• The phenomenon of cheatgrass die-off is a common and naturally occurring stand failure that can eliminate the presence of this annual grass for a year or more, affecting tens to hundreds of thousands of acres in some years. • We designed a study to determine if the temporary lack of cheatgrass caused by die-offs is a restoration opportunity. We seeded native perennial species at three die-offs in the Winnemucca, Nevada, area. • Native grass establishment in die-offs was almost three times higher in the first season at all sites, relative to adjacent areas without die-off. Establishment was five times higher in the die-off at two sites in the second season, and plants produced dramatically more culms in the die-off at the third site in the third season. • Increasing seed rates led to more seedlings establishing in both die-offs and controls, with the strongest effect in the second season. • We suggest that landowners and managers consider targeting die-offs as efficient locations to focus native restoration efforts and that restoration practitioners should consider increasing seeding rates to maximize success.
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Cheatgrass Die-Offs:
A Unique Restoration Opportunity in
Northern Nevada
By Owen W. Baughman, Robert Burton, Mark Williams, Peter J. Weisberg,
Thomas E. Dilts, and Elizabeth A. Leger
On the Ground
The phenomenon of cheatgrass die-off is a common
and naturally occurring stand failure that can
eliminate the presence of this annual grass for a
year or more, affecting tens of thousands of
hectares in some years.
We designed a study to determine if the temporary
lack of cheatgrass caused by die-offs is a restoration
opportunity. We seeded native perennial species at
three die-offs in the Winnemucca, Nevada, area.
Native grass establishment in die-offs was almost
three times higher in the first season at all sites,
relative to adjacent areas without die-off. Establishment
was five times higher in the die-off at two sites in the
second season, and plants produced dramatically more
culms in the die-off at the third site in the third season.
Increasing seed rates led to more seedlings establishing
in both die-offs and controls, with the strongest effect in
the second season.
We suggest that landowners and managers consider
targeting die-offs as efficient locations to focus native
restoration efforts and that restoration practitioners should
consider increasing seeding rates to maximize success.
Keywords: Great Basin, revegetation,
Bromus tectorum, cheatgrass, die-off, restoration.
Rangelands xx(x):1—9
doi 10.1016/j.rala.2017.09.001
©2017 The Society for Range Management.
Cheatgrass (Bromus tectorum) is one of North Americas
most ecologically significant invasive species, growing in
impressively dense near-monocultures across many
parts of the West. Because it is highly competitive, it
is a severe barrier to the survival of seedlings of perennial plants,
especially in sagebrush steppe communities.
1
Cheatgrass die-off,
or stand replacement failure, is a naturally occurring phenomenon in
which a seemingly healthy stand of cheatgrass fails to replace itself.
2
Die-offs result in the complete elimination of cheatgrass at a site for
oneormoregrowingseasons(Fig. 1). The cause of this
phenomenon is under investigation
4
and likely involves one or
more pathogens reaching epidemic levels under certain conditions.
Only actively growing seeds are affected, so dormant cheatgrass
seeds remain in the soil during and after the die-off, often resulting
in a return to cheatgrass dominance within a year or two.
2,5
Because these die-offs occur in remote areas, it can be
difficult to understand how common they are. However, their
distinct color and patterns make them perfect for detection
with aerial or satellite imagery. In a recent remote sensing
study focused on a highly invaded region of north-central
Nevada centered on Winnemucca, we found that over
100,000 hectares of die-off have occurred over the last 31
years (Fig. 2).
6
Throughout the 1.7 million hectare study
area, some years produced no die-off, around one-third of
years produced 4,800 ha or more, and three years each
produced over 40,000 ha of die-off. This study also found
that certain areas (totaling around 15,000 ha) are hotspots
that have experienced die-off four to nine times during the
31-year period. Cheatgrass die-off has also been observed in
other arid shrublands in the west, including Washington,
Utah, Idaho, and Oregon (O. Baughman, personal observa-
tion), and areas of unexpectedly low productivity of
cheatgrass that could be die-offs have been remotely sensed
throughout much of the northern Great Basin.
7
These
die-offs can cause problems for land users because these areas
may experience increased soil erosion, invasions of other weed
species, and a sudden loss of spring forage. However, die-offs
may also represent excellent opportunities for establishing
seedlings of perennial plants, which is what we investigate here.
Can Die-offs Increase Restoration Success in
Areas Where There Are Few Options?
Compared with other forms of temporary cheatgrass control,
such as herbicide or targeted grazing, the die-off phenomenon is
not costly or labor intensive, but it still provides conditions that
may help native plants grow. For example, soil moisture,
plant-available nitrogen, and other essential nutrients are higher
2017 1
in recent die-off soils than soils of nearby areas that did not
experience die-off.
810
We conducted a precision seeding study
to test how die-offs affected perennial grass seeds at a die-off in
Pershing County, Nevada, in 2012.
5,8
We planted Sandberg
bluegrass (Poa secunda) and bottlebrush squirreltail (Elymus
elymoides) into a recent die-off as well as an adjacent intact
cheatgrass stand (control). The die-off supported more
bluegrass and squirreltail through 2 years of monitoring, and
seedlings in the die-off had significantly greater growth and
vigor late in the growing season than those in the control. These
findings were promising, especially considering the competitive
pressure exerted on these native seedlings by cheatgrass, which
was common and returning to dominance during the study.
These promising results suggested that cheatgrass die-offs
can increase restoration success in highly invaded areas, but
our seeding was limited to only one site and two native species
and used a nontypical method of hand-seeding. Therefore,
researchers at the University of Nevada, Reno and managers at
the Bureau of Land Management initiated this follow-up
study to determine if similar results would be found across
multiple die-off sites, seeding a greater diversity of native
species and using typical drill-seeding methods. Additionally,
we were interested in whether simply increasing the seeding
rate could improve native establishment. The questions of our
study were as follows:
1. Do recent cheatgrass die-offs support higher establishment of
native grass, forb, and shrub seeds after mechanical seeding?
2. Do higher seed rates result in higher establishment of
native grass, forb, and shrub seeds, in or out of cheatgrass
die-offs?
Sites, Seeding, and Monitoring
Three sites that contained an area of complete stand failure
(die-off) as well as an immediately adjacent stand of cheatgrass
(control) were selected for seeding (Fig. 1). Buena Vista and
Paradise were formerly dominated by Wyoming sagebrush
(Artemisia tridentata ssp. wyomingensis), while Four Corners was
likely dominated by a mix of Wyoming sagebrush and salt desert
scrub species. At the time of seeding, all sites had been dominated
by cheatgrass for over a decade, with a mix of other exotic and
native species existing at much lower levels. Die-off and control
Figure 1. Many cheatgrass die-offs are so devoid of vegetation that they can be seen from far away, as well as in satellite imagery. Photos are satellite
imagery
3
(top images) and ground-level views (bottom images) of the three sites used in this experiment. Satellite images show the die-off boundary
(dashed outline) and experimental fields in the die-off (light boxes) and control (dark boxes), all of which were fenced soon after seeding. In the ground-level
views, the characteristic gray litter of a recent die-off in the foreground contrasts with the light yellow of dried cheatgrass in the background. Note that the
date (lower left of each panel) and scale (upper right of each satellite panel) vary.
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2
fields were less than 400 m from one another and were each
enclosed with barbed wire fences constructed after seeding.
An approximately 0.2 ha area within each die-off and
control area at each site was designated as the study field, and
Figure 2. In this region of Northern Nevada, over 100,000 hectares of cheatgrass-infested rangelands have experienced cheatgrass die-off over the past
31 years. This map summarizes the number of times areas have experienced the die-off phenomenon over that time, with warmer colors indicating
hot-spots of die-off activity, where the phenomenon is most frequent. The locations for the three sites used in this study are also shown.
Table 1. Seeded species, source information, and seed rates in both PLS/ft
2
and lbsPLS/ac for the single rate*
Species Germplasm origin Production
location
Single rate
(PLS
y
/ft
2
)
Single rate
(lbsPLS/ac)
Fourwing saltbrush Humboldt County, Nevada Wild 2.9 2.0
Spiny hopsage Humboldt County, Nevada Wild 4.2 0.9
Bottlebrush squirreltail Klamath, Klamath
County, Oregon
Warden,
Washington
6.9 2.2
Sandberg bluegrass Hanford, Benton
County, Washington
Connell,
Washington
13.9 0.5
Yarrow Umatilla County, Oregon Lincoln
County, Washington
4.5 0.1
Royal penstemon Douglas County, Nevada Wild 2.5 0.2
Desert globemallow Utah Fresno, California 9.4 0.7
Total 44.3 6.5
*The double rate treatment consisted of the single rate applied twice.
y
Pure live seed (PLS) is % purity multiplied by % germination of the seed lot.
Multiply PLS/ft
2
by 10.76 for seed rate per square meter, and multiply lbsPLS/ac by 1.12 for kgPLS/ha.
2017 3
three treatment areas were established in each field: unseeded,
single seed rate, and double seed rate.
Six perennial native species of grasses, forbs, and shrubs
were selected for the seed mix used in the experiment due to
their commercial availability and likely suitability to one or
more of the sites (Table 1): scarlet globemallow (Sphaeralcea
ambigua),royalpenstemon(Penstemon speciosus), yarrow
(Achillea millefolium), Sandberg bluegrass (P. secunda), bottle-
brush squirreltail (E. elymoides), spiny hopsage (Grayia
spinosa), and four-wing saltbrush (Atriplex canescens). We
selected collections or cultivars that originated from sites that
were as similar as possible to the planting sites to maximize the
benefit from any locally adapted traits.
All sites were seeded the third week of November 2014
using a minimum-till Truax Flex II 86 drill mounted on a
tractor. The unseeded treatment was left completely undis-
turbed to represent site conditions that would occur with no
management intervention. The single rate treatment received
a total of approximately 44 pure live seeds per square foot
(PLS/ft
2
) applied with one seeder application, and the double
rate treatment received approximately 89 PLS/ft
2
applied in
two applications of 44 PLS/ft
2
each (Table 1). At the time of
planting in November 2014, cheatgrass seedlings were just
beginning to green up in all sites except the die-off field at
Four Corners.
All fields were monitored through two growing seasons, at 5
months (April 2015) and 16 months (March 2016) after seeding.
We sampled 20 randomly placed 1 m
2
quadrats in each treatment
to record densities for seeded and resident grasses, forbs, and
shrubs, as well as cheatgrass and other weeds. In June 2017, the
Four Corners site was monitored for the number of flowering
culms, following up on patterns observed in 2016. On a field-by
field basis, the sampled area was scaled down to a smaller area
(e.g., 10 cm × 10 cm for annual weeds) to reduce counting
fatigue if counts were likely to exceed several hundred.
Additionally, 25 randomly selected cheatgrass plants in each
field were measured in the first season for leaf number and
maximum leaf height.
A fully factorial analysis of variance model was used to
analyze the results separately for each sampling period, with
site (Buena Vista, Four Corners, Paradise), die-off condition
(control, die-off), and seeding treatment (unseeded,
single-rate, double-rate) as main effects.
11
Significance was
assessed at the P= 0.05 level.
Our Findings: Seeding Was More Successful
in Die-offs
Estimated precipitation for the three sites was 97% to
101%, 116% to 126%, and 144% to 158% of the 30-year
Figure 3. These images from the Four Corners site in April 2015 (top images) and March 2016 (bottom images) show reduced cheatgrass in the areas
that experienced die-off (left images) compared to unaffected controls (right images). In the first season, large and vigorous seeded native grass seedlings
could be seen in the die-off drill rows, while smaller seedlings were hidden in dense cheatgrass seedlings in the control. By the second year, these
differences were even more dramatic as seeded grasses began to fill the drill rows in the die-off and grow together. While the control still supported
seedlings, they were of a much smaller stature and grew amid much higher cheatgrass density.
Rangelands
4
average for each growing season, respectively.
12
We found
absolutely no seeded shrubs and an insignificantly small
number of seeded forbs surviving in our treatments, which
supports the notion that these kinds of species are particularly
challenging to establish, especially in highly invaded
systems.
13
However, our perennial grass species, Sandberg
bluegrass and bottlebrush squirreltail, did establish in
significant numbers, ranging from 3 to 48 seedlings/m
2
in
the first growing season to 0 to 20 seedlings/m
2
in the second
growing season (Figs. 3 and 4). In the second growing season,
the Four Corners site supported the highest establishment,
averaging 10 to 20 seedlings/m
2
, with the other two sites
showing similar densities of 0 to 11 seedlings/m
2
. Due to the
lack of forb and shrub establishment, the rest of this text is
focused only on the response of the seeded native grasses,
although we recommend future work be conducted to
understand the poor response of these species.
Our results strongly confirm what our previous case study
suggested, which is that die-offs significantly improve our
ability to establish native grasses from seed. We observed an
average of 280% more establishment of seeded native grasses in
the first season in die-off areas relative to controls, and this pattern
was consistent across all sites and seed rates (Fig. 4). In the second
growing season, this difference increased to over 500% more
seedlings in die-offs at two of the three sites, while the third site,
Four Corners, did not show such a pattern. The Four Corners site
visually supported the trend for improved success in die-offs
(Fig. 3), and the likely explanation for the lack of a difference in
density is that large seeded grasses in the die-off had grown
together and were difficult to differentiate from one another,
leading to an underestimation of seeded grass density in the die-off.
In the third growing season, counts of flowering culms of seeded
grasses at Four Corners were over 100-fold higher in the die-off
than in the control (Fig. 4), confirming greater success in the
die-off, despite the lack of difference in density in the second year.
Another important finding is that the patterns of native
grass establishment described were observed despite generally
intense competition with cheatgrass and/or other weeds in
die-off fields in both seasons (Fig. 3,Appendix A).
Additionally, our results were observed in exclosures that
prevented livestock from accessing seedings over the study
period. Although this rest from grazing is standard practice for
post-fire seedings, it remains to be seen if exclosures affect
seeding in die-off areas. Because fences are expensive and time
consuming to construct, we suggest that future research
determine how this practice affects restoration success in
die-off areas.
Our Findings: Increasing Seed Rates
Can Pay Off
Our results strongly suggest that increasing seeding
rates directly increased establishment. In the first growing
season, doubling the seed rate significantly increased the
number of seeded grasses in die-off as well as control
fields at the Buena Vista and Paradise sites by 145% to
437% (average 235%), with no effect at Four Corners (Fig. 4).
In the second growing season, the double-rate treatment
supported 133% to 425% (average 175%) more seedlings than
the single-rate treatment across all sites and fields, with the
exception of the control field at Buena Vista, where there was no
difference.
The double-rate treatment in our experiment was achieved
by applying the single rate twice. This is important to consider
because the extra cutting and packing of the soil or disturbance
to the thatch layer caused by an additional pass of the tractor
and seeder likely affected the seedbed conditions. These
effects may have been positive and may explain some or all of
the benefits of increased seeding rate, as well as why the Buena
Vista site supported three to four times more grasses due to a
Figure 4. Means and standard errors for number of live seedlings (left and middle) and number of flowering culms (right) of both squirreltail and Sandberg
bluegrass per square meter for each seed rate treatment (single, double) in areas that did not recently die off (control), as well as recent die-offs across
three study sites (Four Corners, Buena Vista, Paradise). Third-year data were only taken at the Four Corners site to clarify patterns observed in the second
year. Asterisks indicate significant (Pb0.05) differences between control and die-off fields (asterisks among the bars) and between single and double seed
rate treatments (asterisks below the bars) in analysis of variance models.
2017 5
mere doubling of the seed rate. Ideally, the double rate
treatment would have been applied in a single pass rather
than a double pass, but this was not feasible at the time
of seeding.
The two seed rates used in our experiment, 21 and 42 PLS/
ft
2
for grasses, are both higher than the recommended rate for
a mixed stand involving these two species (~ 14 PLS/ft
2
).
14
Our findings suggest that the single rate was likely too low to
expect maximum success at our semi-arid, 203 to 254mm (8
to 10-in) annual precipitation sites, even in areas with reduced
cheatgrass competition. This is contrary to a more exhaustive
synthesis of restoration in this region, which found no benefit
to increasing similar seed rates for grasses.
15
However, James
and Svejcar
16
identified a need to research better seeding
technologies by demonstrating that the low success of drill
seeding methods may be because they do not place enough
seed at the best depth or into ideal seedbed conditions.
Although we support the need for improved seeding
technologies, our results suggest that in the meantime,
increasing seeding rates of traditional drill seeding may be
an easy way to increase success by exposing more seeds to
appropriate conditions.
Moving Forward with Die-off Restoration
Previous work has shown that die-offs are common,
although localized and unpredictable, and can affect tens of
thousands of hectares in some years.
6
These die-offs are
short-lived, with over 80% returning to cheatgrass dominance
in the next year. Die-offs also experience increases in the
densities of other annual forb weeds. However, despite this
seemingly hostile situation for native species, our research has
repeatedly shown that seeding of native perennial grasses in
the fall after a die-off results in greater success. Considering
that die-offs occur in highly invaded, low-diversity,
low-productivity ecosystems (commonly characterized as
hopeless candidates for restoration), the prospect of any
dependable method for increasing the success of native species
at these sites is welcome news. We propose that cheatgrass
die-off represents a large and underutilized opportunity to
improve establishment of native seedlings.
Cheatgrass die-offs can be thought of as one of several tools
in the revegetation toolbox and present a great opportunity to
focus restoration efforts. Because they are visible in freely
available satellite imagery as early as April/May, managers
could have 4 to 5 months to plan and prepare for seeding in
years with extensive die-offs, a considerable improvement on
post-fire seeding timelines. Prioritizing restoration in hot-
spotsof frequent die-off may further improve restoration
success, and optimizing seed mixes to suit these arid sites
might result in even greater establishment. For example, our
work clearly suggests that we need to do more to understand
barriers to shrub and forb restoration, as we had no success
with these seeds. Though more costly than seedings, die-offs
may be an area where transplanting forb and shrub seedlings
could establish islands within die-off hot-spots,
17
which could
increase natural recruitment when climatic conditions are
good for these species. Finally, post-seeding management may
further benefit these seedings. Pre-emergent herbicide or
targeted grazing may be useful for reducing annual weed
densities in the years following seeding, and these factors
could be tested in future experiments.
We suggest that landowners or managers experiencing
cheatgrass die-offs consider experimenting with seeding these
areas as a means of reintroducing native perennial species to
highly invaded, low-diversity lands, and we would be
interested in hearing reports of any successes or failures with
die-off seeding. Ongoing and future research should lead to
improved understanding of what causes die-offs and can
hopefully lead to useful predictions of when and where die-off
will occur, or even the ability to create new die-offs. In the
meantime, naturally occurring cheatgrass die-offs provide a
rare opportunity for active restoration in some of our most
degraded lands where, until recently, the potential for
improving rangeland resources and values has been considered
a lost cause.
Acknowledgments
The authors thank Jason Sprott for exceptional field
assistance, Rebecca Fritz for aiding in fence construction,
Dashiell Hibbard and Karin Kettenring for help monitoring
seeding success, Susan Meyer for stimulating conversation
and collaboration regarding our cheatgrass die-off work, and
one anonymous reviewer for helpful comments.
Appendix A.Weed Recovery after Die-off
Because the die-off phenomenon does not affect
dormant cheatgrass seeds, many sites return to cheatgrass
dominance in the next growing season. Additionally,
many forb weeds are excellent seed dispersers and appear
to do well in areas recovering from cheatgrass die-off.
Here, we report results of cheatgrass and other weeds in
our treatment plots.
In the first season, all sites supported significantly
greater densities of cheatgrass in the control than the
die-off fields (Fig. A1). In the second year, Four Corners
still strongly showed this trend, Paradise weakly showed
this trend in only two treatments, and Buena Vista had
uniform cheatgrass density across die-off and control
fields. The lower-density cheatgrass in the die-off in the
first season had significantly more culms per plant and was
significantly taller than in the control at all sites (Fig. A2).
These findings show that the cheatgrass present in
die-offs the year after the event is at a lower density but
has higher individual vigor than in adjacent areas that did
not die off and that these differences persist or fade away
by the second year, depending upon the site, all of which
corroborates previous findings.
810
Because of this quick
recovery, the window for restoration benefits after die-off
may be short.
Other weedy species responded to the die-off as well
(Table A1). All three sites had significantly higher densities of
other weed species in the die-off fields in the first year,
Rangelands
6
Appendix Figure A1. Means and standard errors for cheatgrass (top two panels) and weed (bottom two panels) density per square meter across seeding
treatments (unseeded, singlerate, double-rate) in areas that have not died-off (control, white bars) as well as recent die-offs (die-off, dark bars) across sites
(Four Corners, Buena Vista, Paradise) for both the first (left two panels) and second season (right panels). Values from the die-off field at the Buena Vista
site were exceptionally high and are noted above the bars. Note the difference in scale between the first and second year weed panels. Significant
differences between control and die-off fields in ANOVA models are indicated with asterisks (*P b0.05) and hashes (
#
P=0.05-0.06).
Appendix Figure A2. Longest leaf (left) and number of culms per plant (right) for cheatgrass for the first season in areas that have not died-off (control,
white bars) as well as recent die-offs (die-off, dark bars) across sites (Four Corners, Buena Vista, Paradise). Significant differences between control and
die-off fields in ANOVA models are indicated with asterisks (*P b0.05).
2017 7
ranging from 37 to 296 plants/m
2
in the die-offs and from 1
to 50 plants/m
2
in the controls (Fig. A2). The density of other
weed species was generally higher when cheatgrass densities
were lower, suggesting that die-off events release other weed
species from the competitive dominance that cheatgrass
otherwise maintains. While the effect of the die-off on
cheatgrass densities began to fade at some sites in the second
growing season, this effect of die-offs on other weed densities
was stronger and consistent for both years at all sites.
The use of an undisturbed area for the unseeded treatment
prevented us from separating the physical effects of tractor and
seeder-related soil disturbance on weed densities from the
ecological effects (competition, facilitation, etc.) of the grass
seedlings on the dynamics of cheatgrass and other weeds; this
could be included in future experimental designs.
In summary, despite a complex interplay of cheatgrass and
weeds, the bottom line is that recent die-offs supported
dramatically increased establishment of seeded native grasses,
even though they were still infested with weeds and were
quickly returning to cheatgrass dominance.
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Appendix Table A1. List of exotic invasive (weeds), resident native, and introduced exotic species found to be
actively growing in samples at the three sites at the time of seeding (S) and in the first (1) and second (2) year
of monitoring.
Exotic invasive (weeds) Four Corners Buena Vista Paradise
Cheatgrass (Bromus tectorum) S, 1, 2 S, 1, 2 S, 1, 2
Field chickweed (Cerastium arvense) -22
Crossflower (Chorispora tenella) --1
Herb sophia (Descurainia sophia) 221
Redstem filaree (Erodium cicutarium) --2
Clasping pepperweed (Lepidium perfoliatum) 11,2-
Burr buttercup (Ranunculus testiculata) 1, 2 1, 2 2
Russian thistle (Salsola tragus) S, 1, 2 1 -
Tall tumblemustard (Sisymbrium altissimum) 1, 2 S, 1, 2 S, 2
Resident native
Bottlebrush squirreltail (Elymus elymoides) --S
Slender phlox (Microsteris gracilis) 11-
Sandberg bluegrass (Poa secunda) S, 1, 2 S S, 1, 2
Gooseberryleaf globemallow (Sphaeralcea grossulariifolia) S, 1, 2 - -
Small fescue (Vulpia microstachys) -1,2-
Introduced exotic
Crested wheatgrass (Agropyron cristatum) - S, 1 S, 1, 2
Rangelands
8
9. MEYER, S.E., J. FRANKE, O.W. BAUGHMAN,J.BECKSTEAD,AND
B. GEARY. 2014. Does Fusarium-caused seed mortality contrib-
ute to Bromus tectorum stand failure in the Great Basin? Weed
Research 54:511-519.
10. BLANK, R., T. MORGAN,AND D. CLEMENTS. 2011. Cheatgrass
dead zones in northern Nevada. Proceedings of the Society for
Range Management 64:94.
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PILLIOD, M.L. BROOKS, J.C. CHAMBERS,AND J.B. GRACE. 2014.
Long-term effects of seeding after wildfire on vegetation in Great
Basin shrubland ecosystems. Journal of Applied Ecology
51(5):1414-1424.
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(Elymus elymoides) and Sandberg bluegrass (Poa secunda).
Available at: https://plants.usda.gov/java/factsheet. Accessed 17
October 2016.
15. EISWERTH, M.E., K. KRAUTER,S.R.SWANSON,AND M.
ZIELINSKI. 2009. Post-fire seeding on Wyoming big sagebrush
ecological sites: Regression analyses of seeded nonnative and
native species densities. Journal of Environmental Management
90:1320-1325.
16. JAMES, J.J., AND T. SVEJCAR. 2010. Limitations to postfire
seedling establishment: The role of seeding technology, water
availability, and invasive plant abundance. Rangeland Ecology &
Management 63:491-495.
17. MCADOO, J.K., C.S. BOYD,AND R.L. SHELEY. 2013. Site,
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Authors are Research Faculty, University of Nevada, Reno,
Department of Natural Resources and Environmental Science. Reno
NV 89557 (Baughman, owbaughman@gmail.com); Monitoring
Specialist, Bureau of Land Management, Winnemucca District
Office, Winnemucca, NV 89445 (Burton); Monitoring Specialist,
Bureau of Land Management, Salt Lake Field Office, West Valley
City, UT 84119 (Williams); Professor, University of Nevada, Reno,
Department of Natural Resources and Environmental Science, Reno
NV 89557 (Weisberg); Spatial Analyst/Research Scientist, University
of Nevada, Reno, Department of Natural Resources and Environ-
mental Science, Reno NV 89557 (Dilts); and Associate Professor,
University of Nevada, Reno, Department of Natural Resources and
Environmental Science, Reno NV 89557 (Leger). This work was
supported by the Great Basin Landscape Conservation Cooperative,
which had no active role in study design, data collection and analysis,
interpretation, or decisions to submit for publication.
2017 9
... Although people disagree about what causes the die-offs, most recognize these events may be opportunities for opportunities for reseeding rangelands invaded by cheatgrass with desirable species. 2 Cheatgrass die-offs are areas where cheatgrass is usually present but is absent for one or more growing seasons. Winter annual mustards (Brassicaceae) are also absent in die-off areas, and gray litter is usually present. ...
... 16,17 Over 80% of cheatgrass die-offs in northern Nevada from 1985 to 2015 were bare for only one year. 2 This suggests that die-offs are caused by a mobile or short-lived agent, rather than a sedentary or persistent one. ...
... Cheatgrass die-offs in northern Nevada from 1985 to 2015 also developed during dry winters and were more likely following 2, or even 3, years of below average precipitation. 2 These data suggest that similar conditions precede both cheatgrass die-offs and army cutworm outbreaks. ...
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