PROJECT SUMMARY - 2001
Integrated Restoration Strategies Towards Weed Control On Western Rangelands
Robert Nowak & Hudson Glimp Univ. Nevada, Reno &
Nevada Ag. Expt. Sta.
Paul Doescher & John Tanaka Oregon State University
Gene Schupp, Alan Rasmussen, & Chris Call Utah State University
Jeanne Chambers & Robin Tausch USFS Rocky Mountain Research
Laboratory
Dave Pyke USGS Forest & Rangeland Ecosystem Sci. Cntr.
Bob Blank & Tom Jones USDA ARS
Mike Pellant Idaho BLM State Office
Map of location of test plot sites
Although cheatgrass (Bromus tectorum) has been widely
distributed across western rangelands for >70 years, the full
ecologic and economic impacts of this non-native invasive plant
have not yet occurred. Unfortunately, several independent lines
of evidence indicate that the rate at which acreage becomes infested
with cheatgrass is increasing rapidly. Furthermore, the invasion
and spread of a number of emerging secondary weeds is coincident
with cheatgrass infestation. Thus to control the spread of these
secondary weeds, we must first control cheatgrass. Competitiveness
and prolific seed production allow cheatgrass to invade both disturbed
and intact native communities and to dominate after wildfire.
Thus, efforts to control cheatgrass need to focus on these biological
characteristics while simultaneously restoring native plants on
Great Basin rangelands.
Our overall goal is to identify concepts and management strategies
to control the spreading dominance of cheatgrass and other weeds
on Great Basin rangelands and to restore native species and increase
biodiversity. Our primary focus will be cheatgrass because
it is the most widespread and damaging invasive weed, but we will
also examine the extent that secondary weeds complicate cheatgrass
control and native species restoration efforts. Supporting objectives
are:
1. Conduct a series of common experiments across the Great Basin
that test management techniques for controlling cheatgrass and
other weeds, establishing native plant communities, and restoring
ecosystem structure and function while reducing the cost of restoration.
2. Provide an ecological understanding of why restoration techniques
succeed or fail.
3. Develop conceptual and economic bases for choosing appropriate
management techniques.
4. Use partnerships among governmental agencies, universities,
cooperative extension, and land managers to convey knowledge to
ranchers and other professionals.
5. Use partnerships with educators to increase student and public
awareness of invasive species issues and to develop educational
tools that convey solutions to invasive species and native plant
restoration problems.
By combining expertise and sharing resources, our multi-state,
interdisciplinary consortium of research, education, extension,
and agency personnel is poised to identify ecological principles
and fundamental knowledge needed to manage invasive weeds and
facilitate native plant restoration on Great Basin rangelands.
We also plan an active program to disseminate that knowledge to
managers and users of Great Basin rangelands.
The lead institution for this consortium, University of Nevada
Reno, is eligible for small and mid-sized consideration.
RESPONSE TO PREVIOUS REVIEW
The IFAFS panel ranked last yearís submitted proposal
as "outstanding", i.e. in the top 9% of all proposals
considered by the panel. Most of the panelís and reviewersí
comments were laudatory, and we have retained (and in most cases
strengthened) the positive aspects of the previous proposal. These
positive comments included: thorough approach, excellent experimental
design, well designed project management, applicability to a major
problem covering a large area, and strong integration of research,
extension, and education activities.
Negative comments from the panel and reviewer were:
"experiments difficult to carry out" ( We recognize
that our experiments are difficult and technically challenging,
but most of us (key personnel and collaborators) each have >15
years of experience doing these types of studies. Given our publication
records, we have clearly demonstrated the ability to carry out
these experiments. Nonetheless, to help clarify our experiments,
we have added some additional details in this yearís proposal.
"project not on very productive lands" ( Although rangelands
are not as productive in a economic market context as crop lands,
rangelands have a number of other uses such as recreation, wildlife
habitat, aesthetics, and conservation. Furthermore, rangelands
in general cover ~35% of the U.S. land surface, and the area targeted
by our studies covers >100 million acres, i.e. most of 4 western
states and portions of 5 other states. Wildfires on rangelands
also have negative impacts on the social and economic frameworks
of these states. Unless we control the invasive weeds and restore
native vegetation, rangelands will lose almost all economic, recreation,
aesthetic, and conservation value, and the negative impacts of
wildlife will grow. Thus, our results truly have large economic
and social impacts.
"rather pricey" ( We have reduced our request funding
by ~30%. We accomplished this reduction largely by reducing the
number of study areas from 8 last year to 6 this year.
PROJECT DESCRIPTION
Integrated Restoration Strategies Towards Weed Control
On Western Rangelands
Introduction
Cheatgrass (Bromus tectorum L.) is an invasive annual grass that
dominates almost 2.9 million acres of BLM land in the Great Basin
(Fig. 1 - red areas; Pellant & Hall 1994). Cheatgrass has
greatly altered the community and fire dynamics of Great Basin
rangelands by increasing the fine fuel needed to carry frequent
fires (Billings 1990). If present in a community, cheatgrass usually
remains a part of the herbaceous layer until a fire occurs, after
which it expands its dominance by replacing fire-sensitive native
shrubs and by competing successfully with grasses (Young et al.
1987). Thus, fire facilitates the conversion of rangelands from
a perennial-dominated to an annual-dominated system (Billings
1990, Young & Evans 1973, Young et al. 1987). Once converted,
these cheatgrass-dominated sites reduce suitable habitats for
many wildlife species, accelerate erosion, provide an unpredictable
forage supply for livestock, and lower the economic value for
ranchers. Furthermore, secondary weeds are beginning to emerge
as significant components in cheatgrass-dominated lands. For example,
knapweeds (Centaurea spp.) now have a stronghold in central Utah
and in west-central Oregon and are rapidly expanding in central
Nevada; rush skeleton weed (Chondrilla juncea L.) is advancing
in southern Idaho; and yellow starthistle (Centaurea solstitialis
L.) is invading western Nevada, northern Idaho, and northeastern
Oregon. Thus, to decrease the ecologic and economic impacts of
these invasive weeds, we need to break the cheatgrass-induced
fire cycle by restoring Great Basin rangelands with a diverse,
native plant community.
Although cheatgrass has been present in much of the Great Basin
for ~70 years (Mack 1986), its full ecologic and economic impact
has yet to be fully realized. First, almost 14 million acres of
BLM lands in the Great Basin are currently undergoing a transition
to cheatgrass dominance (Fig. 1 - orange areas), with another
62 million acres susceptible to becoming dominated by this exotic
weed (Fig. 1 - yellow areas). Second, the impacts of cheatgrass
are rapidly becoming more acute. For example, historical and paleoecological
evidence indicate that acreage burned each year is increasing
(Tausch et al. 1993, Gruell 1999), and dominance by this exotic
annual grass fueled over 70% of the large fires (>5000 acres)
in the Great Basin from 1980-1995 (Knapp 1998). Finally, the greater
responses of exotic annual grasses to increased atmospheric CO2
suggest that invasions will only worsen in the future if the system
is left unmanaged (Smith et al. 2000).
Two biological features contribute to the remarkable success of
cheatgrass (Smith et al. 1997): prolific seed production and high
competitive ability. Seed production by cheatgrass can be 10-100
times greater on burned sites in the first year after fire, and
although population density may be relatively small during this
first year after a fire, field and modeling studies demonstrate
that cheatgrass populations have an 80-90% risk of exploding to
densities near 10,000 plants m-2 within 10 years (Young &
Evans 1978; Pyke 1995). Cheatgrass competes with native species
for soil water and negatively affects the water status and productivity
of established perennial plants, and the reduced productivity
and greater water stress experienced by the native perennials
persist for at least 12 years after fire (Melgoza et al. 1990).
Greater root elongation at low soil temperatures (Harris 1967)
as well as competitive displacement of root systems (Melgoza &
Nowak 1991) are mechanisms for cheatgrass to compete for limited
soil resources. Thus, strategies to enhance the restoration of
Great Basin rangeland must destabilize the cheatgrass dominance
by reducing the abundance of cheatgrass seed followed by establishing
species that are competitive with cheatgrass.
The Overall Goal of our consortium is to identify the necessary
concepts and management strategies to control the spreading dominance
of cheatgrass and other weeds on Great Basin rangelands and to
restore native species and increase biodiversity. Our Primary
Focus will be cheatgrass because it is the most widespread and
damaging invasive weed. But given that cheatgrass appears to facilitate
invasion of secondary weeds, we will also examine the extent that
these secondary weeds complicate cheatgrass control and native
species restoration efforts. Supporting Objectives are:
1. Conduct a series of common experiments across the Great Basin
that are designed to test management techniques for controlling
cheatgrass and other weeds, establishing native plant communities,
and restoring ecosystem structure and function while reducing
the high cost of current restoration efforts.
2. Provide a sound ecological understanding of why cheatgrass
control and native species restoration techniques succeed or fail.
3. Develop conceptual and economic bases for choosing appropriate
management techniques for the range of conditions that exist within
the Great Basin.
4. Use active partnerships among governmental agencies, universities,
cooperative extension, and land managers to convey knowledge of
the processes, techniques, and results to ranchers and other rangeland
professionals.
5. Use partnerships with educators to increase student and public
awareness of invasive species issues and to develop educational
tools that convey solutions to invasive species and native plant
restoration problems.
Accomplishing these objectives provides solutions for the management
of all lands in the Great Basin regardless of ownership.
Our integrated approach to restoration and weed control addresses
4 of the 5 key areas of the Non-native Invasive Species Program
Area of the IFAFS 2001 RFP. Clearly we cannot prevent the introduction
of cheatgrass and other invasive weeds (Area #1), but by obtaining
the necessary information to restore native species and break
the fire cycle, our studies will help prevent, and even reverse,
the spreading dominance of cheatgrass and secondary weeds (Area
#2). Second, results from our program will provide knowledge about
successful management responses to weed invasions (Area #3). This
knowledge includes not only what is feasible (e.g. what treatments,
what plants, etc.), but also when it may be feasible (i.e. including
areas in varying stages of weed invasion will allow us to identify
the conditions that facilitate or limit reestablishment of native
species). Third, our field experiments provide well-described
systems to monitor long-term success (Area #4), and finally, the
concurrent ecologic and economic studies will quantify the impacts
of species control (Area #5).
Approach
Overall experimental design
To achieve our objectives, we will implement 2 core experiments
that include a series of ecological process studies (i.e. population
ecology, community ecology, etc.) and are complemented by economic
assessments, educational development, and outreach initiatives.
The 2 experiments will be replicated across a 4-state area that
encompasses the range of environmental conditions typical for
rangelands prone to cheatgrass invasion. Both experiments use
a split-plot experimental design with the main plot factor as
weed abundance, with weed abundance varying from: 1) diverse native
vegetation with low cheatgrass abundance in the understory; to
2) cheatgrass as the dominant species but few secondary weeds;
and 3) cheatgrass dominant and active invasion by secondary weeds.
Although typical species for restoration are exotic bunchgrasses
such as the crested wheatgrasses Agropyron cristatum and A. desertorum
(Keller 1979, Johnson 1986), exotic grasses are not a universal
solution to rangeland restoration. Pressure is growing to restore
native perennials because of aesthetic, recreational, and conservation
values and because native rangelands provide benefits to livestock
and wildlife that monospecific stands of exotics cannot (DePuit
1986, Richards et al. 1997, Roundy et al. 1997). Unfortunately,
early trials with native species were largely unsuccessful, and
thus little subsequent research focused on natives ( despite a
growing awareness that native species restoration can succeed
(Roundy et al. 1997). For example, natives such as bottlebrush
squirreltail (Elymus elymoides) have successfully invaded and
suppressed annual weeds (e.g., Hironaka & Tisdale 1963, Hironaka
& Sindelar 1973, Pyke & Borman 1993, Monsen 1994). Thus,
we will concentrate our restoration efforts on native species.
Restoration is often described as directing the successional trajectory
towards some pre-disturbance species assemblage and some prior
level of ecosystem structure and function (Luken 1990; Aronson
et al. 1993). But successional trajectories are seldom linear,
and multiple alternative states exist for any given ecosystem
type (Laycock 1991; Chambers 2000). From both the land management
and restoration perspective, the state-threshold concept is an
important underlying principle (Westoby et al 1989, Chambers 2000),
i.e. alternative vegetative states exist on the landscape, with
some of these states separated by abiotic or biotic thresholds.
A critical aspect in defining thresholds that exist between target
states is to quantify the abiotic and biotic ecosystem variables
that separate them. For the sagebrush-steppe in the Great Basin,
the influence of precipitation and available soil nitrogen on
the competitiveness and abundance of cheatgrass appear to be defining
thresholds.
The influence of annual species such as cheatgrass on perennial
species appears to be smaller during wet years (Harris 1967; Stewart
& Hall 1949). One factor that underlies this precipitation
influence may be competition for spring moisture. For example,
greater depletion of soil moisture in shallow soil layers was
evident in early spring with cheatgrass competition (Melgoza et
al. 1990), and the conversion of oak woodlands to annual grasslands
in California results in less soil moisture available in the spring
(Gerlach 2000). Although our experiments are not designed to test
directly for the influence of varying water availability on competitive
interactions (i.e. we do not impose irrigation or rain-out treatments),
selection of replicate sites in areas with different mean annual
precipitation coupled with repetition of experiments in a second
year allow us to indirectly assess effects of variation in water
availability.
Recent field studies have shown the importance of available inorganic
nitrogen in controlling cheatgrass establishment (McLendon and
Redente, 1991; Young et al., 1999), and cheatgrass invasion rapidly
alters nitrogen cycling (Evans et al. 2001). Cheatgrass tends
to thrive in a high nitrogen environment but is inhibited in a
low one (McLendon & Redente 1991; Redente et al. 1992; Young
& Allen 1997; Young et al. 1999). Application of sucrose,
which causes microbial uptake of inorganic nitrogen, reduces cheatgrass
density. Conversely, addition of inorganic nitrogen can encourage
establishment in non-invaded areas and dramatically increase cheatgrass
density and competitiveness. Thus, available inorganic nitrogen
is a catalyst that influences the competitive stature of cheatgrass.
The first experiment investigates if the competitive interactions
between cheatgrass and native species change with weed abundance
or with soil N availability. Results from this experiment will
indicate: 1) if weed abundance or soil N availability alters cheatgrass
growth and thus its competitive advantage; 2) which native species
are more competitive with cheatgrass under these different environmental
conditions; and 3) the underlying ecological mechanisms for the
observed results. The second experiment investigates if the effectiveness
of 3 different restoration treatments changes with weed abundance.
Two of the restoration techniques (a prescribed fire and a prescribed
grazing treatment) are targeted at reducing the cheatgrass seed
bank, whereas the third investigates if more competitive native
species (identified in the first experiment) further enhance cheatgrass
control. Results from this second experiment will indicate: 1)
if prescribed management treatments are capable of reducing either
the cheatgrass seed bank or soil N availability, and thus enhance
the establishment of native species; 2) if restoration strategies
that incorporate a transition community of competitive species
have greater success; 3) the extent that weed abundance influences
the control of cheatgrass and establishment of natives; and 4)
the underlying ecological mechanisms for the observed results.
Although our focus is primarily cheatgrass, we will also quantify
effects on perennial species as well as secondary weeds.
Concomitant with the ecological investigations in these experiments,
a least-cost economic analysis will determine the economic feasibility
of different restoration strategies. Because all the monetary
benefits of native plant restoration (e.g. monetary benefit of
increased ecological health, aesthetics, etc.) cannot be quantified
accurately, the least-cost method is the most appropriate analysis
technique. These economic analyses will account for differences
in weed abundance, precipitation, and soil N availability as well
as consider the economic benefits of intensive spring grazing
on cheatgrass for livestock ranches.
In addition, we will develop a robust extension and educational
program that:
produces practical, informational publications and handbooks for
private and public land managers
incorporates extension agent exposure at field days and training
sessions
includes internet access to publications, information, related
websites, and chat rooms
integrates invasive species and restoration issues into K-12 core
curricula
incorporates course materials plus research and management experiences
for college undergraduates provides training workshops for teachers,
resource specialists, and media representatives has proactive
community outreach and public relations.
In both experiments, perennial plant cover, density, and biomass
will be used as measures of plant "success". High values
of these perennial plant metrics are desirable characteristics
of almost all restoration efforts, and they are relatively simple
to quantify. Clearly, cover, density, and biomass are not the
only goals of restoration - we also need to understand why certain
treatments resulted in higher cover and biomass. Thus, a series
of ecological process studies that investigate seedling establishment,
seed bank dynamics, resource competition, and soil processes (see
Section 5.2.2) are integral parts of our experiments. This mechanistic
understanding in turn provides the ability to extrapolate our
results to scenarios that have different sites, different conditions,
or different restoration techniques. Cover, density, and biomass
of perennial plants will be determined at peak biomass on all
plots using standardized protocols (NARSC 1996). (Tausch will
supervise these measurements.) Production, reproduction, and seed
banks of cheatgrass and secondary weeds will also be examined
(see section 5.2.2).
Each experiment has 6 replications per main plot treatment (we
refer to these replicates as "study areas"), with replicates
distributed across the 4 western states that comprise the majority
of the Great Basin. All replicates will share the following characteristics:
Range site characterized by Artemisia tridentata subsp. wyomingensis.
These sites constitute at least 25% of the entire sagebrush zone
in the Great Basin (West 1999).
Loamy to silt loam orthid soil with >1 m to any argillic or
hardpan layers.
Three replicate study areas will be located in an area with relatively
low precipitation (mean annual precipitation 200-230 mm) and 3
in areas with relatively high precipitation (mean annual precipitation
300-330 mm). Geographic locations of these study areas are shown
in Fig. 1.
The 3 main plot treatments at each study area reflect an abundance
of weeds in terms of both frequency and diversity. These treatments,
from relatively low to relatively high weed abundance, are:
Native community: >70% frequency of native perennials, <20%
frequency of cheatgrass, and <<1% frequency of secondary
weeds.
Cheatgrass dominated: <20% native perennials, >60% cheatgrass,
<<1% secondary weeds.
Weed infested: <20% native perennials, >60% cheatgrass,
5-10% secondary weeds.
As in any field study, true statistical replicates are very difficult
to obtain. For example, weather variation, soil structure, and
other subtle site factors will not be identical among all sites.
Thus, soil properties of each study area will be quantified (see
section 5.2.2), and maximum and minimum daily air temperatures
and precipitation will be measured for the duration of the studies
at each site.
Furthermore, 4 methods are available to account for the inherent
variation that will occur:
First, we have purposely introduced the potential for variation
in timing and amount of precipitation among the study areas. Obviously,
nature may not cooperate, but the alternatives (irrigation treatments,
rain-out shelters) are much too expensive to implement. Nonetheless,
the extent that nature "cooperates" impacts the statistical
analyses that we will need to employ, ranging from analysis of
variance, to analysis of covariance, and to regression and meta-analysis
methods as uniformity decreases.
Second, we will repeat the competition screening trials of Experiment
1 in 2 consecutive years to get a measure of year-to-year variation
within a site.
Third, we will use a series of ancillary "garden" plots
in the experiments to assess weather and site variation. These
"gardens" are seeded in the same way as the perennials,
but are carefully weeded to remove all cheatgrass plants, which
allow the perennials to achieve their maximum growth potential
under the prevailing weather and other site conditions. To account
for site-to-site and year-to-year variation in prevailing growth
conditions, vegetation measurements on experimental plots are
referenced to the garden plots. This relative method facilitates
statistical analyses across the replicates by using either the
ratio of experimental to garden plot with standard split-plot
analysis of variance or the results from the garden plots as a
co-variate in analysis of co-variance.
A fourth technique is meta-analysis, which is a statistical technique
to quantitatively synthesize and analyze a collection of experimental
studies (Osenberg et al. 1999). Although meta-analysis in the
ecological literature usually is used for retrospective analyses
of published data (e.g. Curtis & Wang 1998; Gurevitch et al.
1992), the concepts and procedures that are inherent in meta-analysis
will enhance our ability to synthesize the results from our studies.
We plan to apply meta-analysis to achieve 2 distinct goals: 1)
to aggregate the results from each site and from different years
as a more powerful test of our null hypotheses; and 2) quantitatively
estimate the magnitude of the restoration response as influenced
by the environmental and biological variables that we measure
in our experiments.
Experiment 1: Competitive interactions
The first experiment focuses on variation in the competitive relationships
between cheatgrass and native species with weed abundance and
soil N availability. Various scientists suggest that some native
species, such as Elymus elymoides (Hironaka & Tisdale 1963;
Hironaka & Sindelar 1973, 1975; Humphrey & Schupp 1999),
are able to compete effectively with cheatgrass, and the species
and lifeform of neighboring plants may reduce cheatgrass seed
production by 75% (Reichenberger & Pyke 1990). Although these
natives may not be the most desirable species to dominate a completely-restored
site, they may provide an intermediate transition state to facilitate
conversion from cheatgrass dominance to a diverse, perennial native
plant community. Given that some native species compete effectively
with cheatgrass but that the ability of cheatgrass to compete
with any 1 native species varies with weed abundance or soil N
availability, specific objectives of this experiment are: 1) identify
promising plants that can be used to enhance the transition from
cheatgrass dominance to a diverse, native plant community; 2)
determine if competitive interactions between native species and
cheatgrass change with weed abundance and available soil N; and
3) understand the mechanisms that explain variations in cheatgrass
competitive ability. Because the potential number of species that
could be used in this experiment is very large and hence the number
of treatment combinations would quickly become unmanageable, we
have split this experiment into: a) a screening trial focused
on the first objective (identifying promising plants); and b)
an experiment focused on the second objective (mechanisms of competition)
that uses species with representative life histories.
The competition screening trial will have a 3x2x25x2 split-split
plot design (Fig. 2A) with weed abundance as the main plot factor,
presence/absence of invasive weeds as the split plot factor, and
plant variety as the split-split plot factor. All invasive weeds
will be removed from half of each of 2 blocks (i.e. within site
replicates) using an application of the pre-emergent herbicide
OUST( (sulfometuron methyl) in the fall prior to seeding (i.e.
during Year 1) coupled with hand weeding as needed. In the other
half of each block, invasive weeds will be allowed to germinate
and grow unimpeded. Within each split plot, a randomized block
design will be used in which 25 plant varieties are completely
randomized within each block. The plant accessions selected for
screening are: 4 accessions of Pseudoroegneria spicata (ëGoldarí*,
Anatone*, P-7*, Acc:238*); 3 of Elymus wawawaiensis (ëSecarí*,
DPPX, E-35); 5 of Elymus elymoides (Sand Hollow*, Paradise Valley*,
Mountain Home, Fish Creek*, Toe Jam Creek); 4 of Achnatherum hymenoides
(ëNezparí*, ëRimrockí*, Rimrock HG*, Acc:89);
4 of Leymus cinereus (ëTrailheadí*, ëMagnarí*,
L8PX-1, Nevada MOPX ); 3 of Poa secunda (ëCanbarí*,
Yakima*, Mountain Home*); a forthcoming release of Achillea lanulosa;
and commercially available Agropyron cristatum. Accessions with
an asterisk could be available in quantity for Experiment 2. Seed
of other accessions would not be available in the necessary time
frame for Experiment 2, but they are included in Experiment 1
because their performance is of long-term interest. In a 26th
plot, no perennials will be seeded, plants other than invasive
weeds will be hand weeded, and invasive weeds will be allowed
to grow to their maximum potential given the prevailing site and
weather conditions. Individual 1.5 m x 2.5 m plots will be seeded
with a single plant variety at 204 pure live seeds (PLS) m-2.
These screening trials will be seeded in the second year of the
study and will be repeated in the third year.
Evaluation of the competition screening trials will involve measurement
of plant traits that potentially indicate greater competitive
ability with cheatgrass. These traits include: first leaf length,
seedling establishment (frequency as measured with a calibrated
rod), and plant height (year 1); frequency of plants heading and
shoot biomass (year 2). Ogle (NRCS) and Jones (USDA ARS) will
supervise and assist with the competition screening trials.
The experiment to examine mechanisms of competition will have
a 3x2x29x2 split-split plot (Fig. 2B) experimental design with
the original weed abundance of the site as the main plot factor,
soil N availability as the split-plot factor, and seeding combinations
as the split-split plots. Within each split plot, a randomized
block design will be used in which the 29 seeding combinations
are completely randomized within each of 2 blocks. Because the
secondary weeds are listed as noxious weeds and thus by law we
cannot seed them into plots, this experiment focuses on cheatgrass
competition.
Competitive interactions with cheatgrass will be examined for
the following individual species and species mixture: 1) monocultures
of 6 native perennial species with different life history strategies
and physiological characteristics; 2) a mixture of the 6 native
species to maximize potential resource use; and 3) monocultures
of crested wheatgrass because it is still the most frequently
used introduced species, but its ability to compete with cheatgrass
has not been rigorously assessed relative to that of native species.
Many of the same native species exist across the broad geographic
area of the Great Basin, but their relative importance and, thus,
appropriateness for restoration varies. Nonetheless, the same
species have been chosen for all 6 study sites in order to allow
statistical comparisons across all replicates. The species are:
Artemisia tridentata subsp. wyomingensis (shrub, uses soil moisture
all year, roots throughout entire soil profile), Poa secunda (bunchgrass,
earliest season moisture, shallowest rooting), Elymus elymoides
(bunchgrass, primarily early season moisture, relatively shallow
rooting), Pseudoroegneria spicata (bunchgrass, mid-season moisture,
relatively extensive rooting), Crepis acuminata (tap-rooted forb,
mid-season moisture, deep roots), and Achillea millefolium (rhizamotous
forb, mid-season moisture, surface mat of roots). Although we
recognize that the short study period (two years) may not allow
sagebrush seedlings to become a competitively active component
of the community, sagebrush is the dominant native shrub in the
Great Basin and will eventually exert an important influence on
competitive interactions.
The effect of cheatgrass competition on the establishment of the
perennial species as well as the effect of the perennial plants
on cheatgrass reproduction will be evaluated by seeding 3 different
densities of cheatgrass into a fixed density of each of the perennial
plant monocultures and into 2 densities of the native species
mixture. The density of the monocultures and the lower density
for the native species mixture will be 204 seeds m-2. The density
of the higher density native species mixture will be 408 seeds
m-2. The densities of cheatgrass will include a control (no cheatgrass),
a low level of introduction (10% of the perennial monoculture
densities and of the less dense species mixture; i.e., 20 seeds
m-2) and a high level of introduction (50% of the perennial monoculture
densities and of the less dense species mixture; i.e., 100 seeds
m-2). The effect of the cheatgrass in the absence of the perennial
species will be examined by seeding cheatgrass alone at the two
densities (20 seeds m-2 and 100 seeds m-2).
The study site will include an area large enough to accommodate
the experimental plots plus a 10 m buffer zone. The plots will
be prepared the fall prior to planting (i.e. during Year 1) by
a one-time application of OUST( timed to minimize cheatgrass establishment
and seed banks. The plots will be seeded the following fall (Year
2) as dormant plantings. Soil N availability will be altered on
half of each block using sugar applications similar to those in
our earlier studies (Young et al. 1999). Individual plots will
be 1.5 m x 2.5 m with one half of the plot reserved for nondestructive
sampling and the other half for destructive sampling. A planting
grid with a uniform 7 cm spacing (204 seeds m-2) or 3.5 cm spacing
(408 seeds m-2) will be used to obtain the proper density of the
individual species and species mixture. For the treatments with
cheatgrass, the additional 20 or 100 cheatgrass seeding locations
will be superimposed over the uniform seeding grid and will be
randomly located. Local seed sources will be used for cheatgrass
and, when possible, for the native species. Seed viability of
all species will be determined prior to seeding, and we will use
only seed lots with >90% viability. Seed burial depths will
be selected to maximize germination and emergence for each individual
species. The plots will be weeded during the first growing season
to maintain the proper plant densities. Perennials often require
2-3 years for establishment and seedling mortality can occur in
the second year if cheatgrass densities increase. Thus, the planted
cheatgrass will be allowed to seed in the first year, and all
plots will be monitored one to two additional years.
Experiment 2: Restoration strategies
The second experiment focuses on restoration strategies and how
weed abundance influences restoration success. The experimental
design for this restoration experiment is a 3x4x2x2 split-split
plot (Fig. 3), where the main plot factor is weed abundance, the
split-plot factor is restoration strategy, and the split-split-plot
factor is seeding mix. The restoration strategy (split-plot) factor
consists of 4 potential methods to control cheatgrass: 1) no treatment
(i.e. control); 2) a prescribed grazing treatment targeted to
reduce current seed production by cheatgrass; 3) a prescribed
burn-seed-burn-seed treatment targeted to reduce both the cheatgrass
seed bank and cheatgrassí access to available soil N; and
4) a herbicide treatment to serve as an experimental reference
point. The seed mix (split-split plot) factor has 2 seed mixes:
1) the same seed mix used in the competition mechanism experiment;
and 2) the 6 varieties from the competition screening trials that
were found to be most competitive with cheatgrass (and thus represents
a transition community from cheatgrass to the desired community).
(Note: Selection of these 6 varieties will also depend on sufficient
seed availability from our seed increase efforts.) The overall
goal of this restoration experiment is to determine the relative
success of restoration strategies that incorporate prescribed
methods to control cheatgrass competition and its prolific seed
production. Specific objectives are: 1) determine if prescribed
fire or grazing management reduces cheatgrass competition for
available soil N and seed bank, and thus enhances the establishment
of native species; 2) determine if the presence of secondary weeds
influences the control of cheatgrass and establishment of natives;
3) determine if a transition community of competitive natives
can be established more readily than a diverse community of different
growth forms; and 4) understand the underlying ecological mechanisms
for the observed results.
The prescribed grazing treatment is a high intensity, short duration
grazing in the spring during seed filling (before cheatgrass turns
purple) to reduce current seed production by cheatgrass. The burn-seed-burn-seed
treatment is a novel restoration strategy that is designed first
to reduce weed seed production, then to deplete available soil
N. The first burn is a slow moving, hot fire in early summer (prior
to seed dispersal) to reduce the cheatgrass seed bank. A cover
crop of annual rye is then seeded that fall. The cover crop has
2 purposes: first to uptake soil N leaving less available to the
invasive weeds, and second to provide fine fuels to carry the
second prescribed burn. (Note that if fuel loads are not sufficient
to carry a prescribed fire, a crop-residue straw will be added.).
The second burn is a low-intensity head fire to further reduce
the cheatgrass seed bank as well as to volatilize nitrogen, and
the second seeding is the final seed mix. Because herbicide restoration
treatments have a high success rate in controlling cheatgrass
before restoration, they serve as an experimental standard to
judge the relative success of the other treatments. [Note: We
are not specifically advocating the use of herbicides (selection
of a specific herbicide and dosage is beyond the scope of our
studies), but as in the case of sugar applications, we recognize
its utility in an experimental framework.] OUST( will be used
because of its relatively short half-life, low toxicity, and current
use to control cheatgrass in the general study area (Pellant et
al. 1999).
At each site, treatments will be applied in a randomized block
design, with 2 blocks per site. Individual plots will be relatively
large (4 ha) to provide better simulation of large-scale land
treatments as well as more realistic cost estimates for each restoration
strategy. The restoration experiment will be implemented in Year
3 of the study, and we will continue to monitor the treatments
for a second year to assess if promising results persist for a
second year.
Ecological processes
Process: Seedling establishment (Pyke, Schupp, & Chambers)
Null Hypothesis: Perennial plant seedling establishment will not
differ with varying levels of cheatgrass competition.
Expected Result: Increasing densities of cheatgrass will result
in increased seedling mortality and, thus, decreased establishment
of the perennial species.
Null Hypothesis: Reproduction of cheatgrass will not differ among
the perennial monocultures or mixtures.
Expected Result: Cheatgrass reproduction will be lower for species
monocultures that use soil moisture earlier in the spring and
lowest in the native perennial mixture.
Seedling Establishment Methods: Seedling emergence and survival
will be monitored three -times during the growing season (growing
season dependent: April or May, June and late July) in the nondestructive
portion of the plots using the planting grids seeding as a guide
for mapping and censusing individuals. During the first year after
seeding, both cheatgrass and the target perennials will be censused
along with any secondary weeds that survive the plot treatments.
In subsequent years, only the perennial species will be censused
using the planting grids. Weed population sizes in subsequent
years will be estimated by counting individuals in three randomly
placed 0.1- m2 quadrats in each non-destructive plot. At the end
of each growing season, weed reproduction will be estimated by
counting the seeds on 15 randomly selected plants per plot. The
seeds will be returned to the plot and spread over the surface.
At the end of the study, 10 randomly located individuals of the
surviving target perennials (or all of the surviving individuals)
will be harvested from each plot and dry mass will be determined.
Process: Weed reproduction and seed bank dynamics (Chambers,
Pyke, & Schupp)
Null Hypothesis: Reproduction and seed banks of cheatgrass and
secondary weeds will not be affected by restoration treatments
that include prescribed burning or grazing followed by seeding
perennial species.
Expected Results: Both prescribed burning and grazing should at
least decrease cheatgrass seed banks and reproduction the year
of the treatment. In subsequent years, seed production and seed
bank densities of cheatgrass and secondary weeds will depend largely
on the degree to which the seeded perennial species (1) establish
on the treated sites and (2) effectively compete with cheatgrass
and secondary weeds.
Seed Bank Methods: The seeds of cheatgrass typically mature in
early summer, have a short after-ripening requirement, and then
become highly germinable. Knapweeds and rush skeletonweed, the
dominant secondary weeds on our sites, have seeds that mature
from mid-summer to late fall and have more restrictive germination
requirements. Cheatgrass seeds are larger than the secondary weed
seeds, but significant vertical movement of seeds is unlikely
given the soil types on the study sites (Chambers 2000). To assess
densities of weed seeds in the seed bank, seed bank samples will
be collected after most seeds have dispersed in the fall (to determine
the current yearís production) and the following spring
after germination is complete (to determine seed bank carryover).
Thirty, randomly-located samples will be collected for each treatment
combination. Soil cores (10 x 10 cm and 2 cm deep) will be collected
and separated into two depths: the litter layer and the 0-2 cm
soil layer. Fall collected samples will receive a 60-day wet,
cold stratification treatment. Spring samples will be allowed
to dry for 30 days, and then will receive the wet, cold stratification
treatment. After stratification, the soil samples will be thinly
spread (< 1.0 cm) over moistened sterilized sand in a greenhouse
with fluctuating day/night temperatures. Samples will be kept
moist, and germinated seedlings of weeds will be counted and removed
after 2 weeks and again at the end of a 6-week germination period.
Samples will then be allowed to dry down and rewatered to check
for additional seedlings.
Reproduction Methods: Seed production of cheatgrass and secondary
weeds will be estimated on per individual and per unit area bases.
Plot sizes for estimating reproduction will likely decrease for
successive years after fire or grazing because weed populations
will likely increase in successive years. For individual plant
reproduction, 30 randomly-selected plants will have all seeds
counted before dispersal. For reproduction per unit area, we will
determine the appropriate number of plots, randomly place these
plots, and then measure plant density and number of seeds on all
plants in the plot.
Process: Resource Competition (Doescher & Svejcar)
Null Hypothesis: Perennial plant water status will not vary with
weed competition, as measured by soil water extraction and water
status of perennial plants.
Null Hypothesis: Perennial plant water status will not vary with
restoration strategies.
Expected Results: If cheatgrass competition is the ultimate reason
why restoration efforts fail, then we expect decreased perennial
plant biomass with cheatgrassinduced faster depletions of soil
water and consequently greater water stress. If the presence of
secondary weeds has synergistic detrimental effects on the perennials,
then we expect further decreases.
Null Hypothesis: Total aboveground plant nitrogen of perennials
will not vary with weed competition or with restoration strategies.
Expected Results: If N availability is important for cheatgrass
competitive success, then the proportion of total plant N in perennials
should be positively related to their competitive ability, as
measured by their relative increase in biomass. Furthermore, the
relative increases for treatments that are targeted to reduce
available soil N (e.g. sugar applications and the burn-seed-burn-seed
restoration strategy) should be greater. The extent that secondary
weeds alter these relationships indicates the extent that they
also compete for N.
Resource Competition Methods: Measurement of soil water extraction
will be made using 30- and 50-cm long TDR probes that are installed
near the center of each plot. Although water can infiltrate below
50-cm soil depth, our previous studies did not show significant
effects of cheatgrass competition on soil water extraction at
60-cm or deeper soil depths (Melgoza et al. 1990). Soil moisture
will be measured twice per month. This technique allows direct,
repeatable, and non-destructive measurements of soil moisture
content. Concordant with the measurements of soil moisture, plant
water status will be determined at predawn and midday using the
pressure chamber technique (Boyer 1995). Soil water extraction
and plant water status will be measured on all treatment and garden
plots. Deviations of soil water extraction and plant water status
on experimental plots from those on the garden plots provides
a relative measure of weed competition, and these deviations will
form the data base for statistical analyses. Total aboveground
plant N will be measured similar to our earlier studies (e.g.
Leavitt et al. 2000): sampling 3 individual plants per species
per plot, compositing the individuals, finely grinding the biomass,
and then analyzing with a CHN analyzer. We recognize that these
measurements of aboveground N pool sizes underestimate total plant
N uptake because they do not include belowground plant N, and
thus they potentially confound comparisons across species. However,
because the decomposition rates of shoot biomass generally is
slower than that of root tissues, greater aboveground plant N
in perennials potentially ties up that N for a longer period of
time.
Process: Soil nutrient status and weed competition (Blank,
Hilty, & Johnson)
Null Hypothesis: There is no threshold of soil nitrogen availability
above which the establishment of cheatgrass or secondary weeds
is favored.
Null Hypothesis: Invasive weeds do not alter soil nutrients.
Expected Results: We will enumerate boundaries of soil nitrogen
availability and the availability of other soil nutrients that
limit the establishment of cheatgrass and secondary weeds. For
example, is there a threshold inorganic nitrogen level below which
cheatgrass establishment is retarded relative to native perennial
grasses? If such a threshold exists, what is its value and how
do we manage the ecosystem to remain below that value? Do other
soil nutrients influence the competitive stature of cheatgrass?
Does cheatgrass alter the soil environment to favor its competitive
stature as we have shown for Lepidium latifolium (Blank &
Young 1999). In addition, we will determine if a prescribed series
of burns can lower available soil nitrogen levels such that more
nitrogen efficient native perennial grasses can re-establish in
relative freedom from cheatgrass.
Soil Nutrient Methods: Soil nutrient studies will be overlain
upon plant competition and restoration plots. Using a replicated
factorial design, we will measure the following attributes over
season (spring, summer, fall), by microsite (plant canopy, interspace)
and among the various plot treatments: 1) in situ nutrient availability
as captured by mixed anion and cation resin exchange capsules
placed at 5 cm (NO3- , NH4+, Ca+2, ortho-P, Mg+2, K+, Fe, Mn,
Cu, Zn); and 2) from homogenized bulk soil samples 0-10 cm, KCl-extractable
NO3- and NH4+, CEC, pH, SOM, soil enzyme activities of phosphatase,
urease, asparaginase and amidase, 30-day aerobic mineralization
potentials of NO3- and NH4+. Again using the same statistical
design, cheatgrass and secondary weed aboveground mass will be
harvested after maturation and analyzed for total N, P, K, Ca,
Mg, and S. Plants will be chosen to represent a range of vigor
from weak to robust. Correlation of a particular nutrient content
in plant tissue with the corresponding soil nutrient content across
the range of vigor types will expose the controlling nutrient
and define a threshold. Regression techniques will be used to
locate trends in our nutrient data set with other measure attributes
on the plots such as cheatgrass density and biomass.
Process: Soil microbial community and biological crusts
(Hilty & Blank)
Null Hypotheses: Functional diversity of soil microbial communities
is not different: a) among communities with different levels of
weed abundance; and b) between native plant communities and sites
where restoration treatments have been applied.
Expected Results: If the soil microbial community is significantly
changed following the invasion of weeds or due to restoration
treatments, then subsequent restoration attempts with native species
may fail because organisms (e.g. mycorhizzae) necessary for native
plant establishment and survival, or for proper nutrient cycling,
may not be present (Allen 1995).
Null Hypothesis: Reinvasion of sites by biological crust organisms
(cyanobacteria, algae, moss, lichens) is not affected by type
of restoration treatment.
Expected Results: Biological crusts (lichen, moss, algae, etc.)
are sparse with regards to both cover and species diversity in
cheatgrass-dominated communities. Restoration treatments (burning,
herbicide, high-intensity livestock use, and seeding) also impact
biological crusts. However, we have shown that biological crust
reestablishment following restoration of native plant community
structure is possible, and reestablishment of biological crusts
in the restored plant communities may be important to future exclusion
of cheatgrass (Kaltenecker 1997; Kaltenecker et al. 1999). We
expect analogous results when secondary weeds are present.
Soil Microbiology Methods: 1) Random soil samples 2.5 cm diameter
x 10 cm deep will be extracted from each native plant community
(control) and restoration treatment replication each fall and
spring (prior to and after treatment). Soil samples will be collected
early during the period of active growth for cheatgrass and at
peak rates of growth. Analyses will include determination of bacterial
and fungal functional diversity using the Biolog and Fungilog
methods of evaluating carbon substrate use (Zak et al. 1994; Dobranic
and Zak 1999), assessment of mycorrhizal inoculum potential (MIP)
(Schwab and Reeves 1981), and soil chemistry parameters (see soil
nutrient process above). 2) Random soil samples 5 cm diameter
x 1 cm deep will be collected from the soil surface in each native
plant community (control) and restoration treatment replication
each fall (prior to and after treatment). Photosynthetic biomass
of surface soils (cyanobacteria, algae, moss protonema) will be
estimated by spectrophotometric determination of chlorophyll a
and b (Belnap 1993; Matthes-Sears et al. 1997). Visual cover of
biological crust will be estimated in randomly placed plots within
each treatment.
Data Analyses: Biolog data will be analyzed by creating similarity
matrices and applying cluster analysis to look for similarity
in composition between treatments. Canonical correspondence analysis
will be used to investigate the relationship between the composition
of the microbial community and soil variables. Soil chemistry,
MIP and biological crust biomass and cover will be compared between
treatments using analysis of variance.
Process: Soil physical properties (Norton, Johnson, Monaco)
Null Hypothesis: Invasive weeds do not alter soil characteristics
in ways that inhibit restoration of native perennial plant communities.
Expected Results: Invasive weeds modify the soil environment through
positive feedback mechanisms, and these soil impacts likely increase
with increased age of invasion. These changes may culminate in
altered soil physical and hydrological properties that affect
the siteís amenability to restoration or ability to recover
naturally. Organic matter turnover is more rapid and shallower
beneath fast-growing, fine-stemmed invasive annual grasses than
under desirable grasses and shrubs. Dominance of annuals generates
a carbon-limited soil environment with relatively abundant mineral
N ("open" N-cycle). In contrast, soils beneath perennial
plants store organic matter in relatively recalcitrant forms and
are characterized by limited available N and rapid microbial immobilization
("closed" N-cycle). These shifts in composition and
distribution of soil organic matter, along with altered plant
canopy characteristics, may change how wind and water interact
with the soil surface and subsurface. These combined effects could
in turn lead to changes in: 1) soil texture and structure; 2)
soil moisture content and available water holding capacity; and
3) hydraulic conductivity, runoff, and erosion. Improved understanding
of how soil properties change with weed invasion and accumulate
over time are important in order to avoid positive-feedback mechanisms
that contribute to ecosystem degradation.
Soil Sampling Methods: Impacts of invasive weeds on soil physical
properties will be examined by comparing soil organic matter,
soil morphology, and soil hydrological attributes from the 4 restoration
treatments as well as from analogous long-term native and weed-invaded
sites. We will excavate, describe, and sample one soil pit to
1.5-m depth within each treatment by standard procedures. Auger
samples from the bottom of the pits allow comparison of geomorphic
setting among treatments and among sites. For each soil pit, we
will establish transects consisting of four sample points to measure
infiltration rate in the field and to collect soil samples to
the depth of the A horizon or the deepest rooting zone. Samples
will be analyzed laboratory for particle-size distribution, water-stable
aggregate content, pH, bulk density, total organic C, total N,
microbial biomass, and recalcitrant C.
Economic assessment (Tanaka & McCoy)
Most economic analyses of noxious weeds on rangelands has focused
on those that are either poisonous to domestic livestock (Nielsen
et al. 1988, Torell et al. 1988) or are in an active expansion
mode with few benefits for domestic livestock (Bangsund et al.
1996, 1999). There is no information available on the economics
of restoring cheatgrass dominated rangelands to native vegetation.
Most of the economic analyses related to controlling one species
to benefit another have focused on the benefit to livestock forage
production (McDaniel et al. 1986, Workman and Tanaka 1991, and
many others).
Estimating the economic benefits from restoring rangelands when
the objective is community structure, ecological health, and native
plant species restoration is difficult. Of the two methods available,
the contingent valuation and hedonic pricing methods, neither
is likely to provide useful information for making restoration
decisions. In the first case, a willingness-to-pay value derived
from a survey will be site and situation specific and has many
inherent theoretical and practical difficulties. In the latter
method, comparing land values from weed infested and noninfested
rangelands adjusted for different sales characteristics may lead
to a difference in value, but that value is likely most closely
tied to livestock use (Godfrey et al. 1988). While this would
be an interesting test, it will not help in making a decision
regarding the restoration of rangelands. Hansen et al. (1991)
have speculated, although not tested, that the costs of preserving
or restoring biodiversity will be covered by the social, economic,
and ecological benefits associated with such a strategy. One effort
to calculate some of the recreational values lost due to leafy
spurge infestations sought to determine the economic impact on
regional economies using an input-output model (Bangsund et al.
1993). This model, however, looks at changes in gross expenditures
(sales) and not on the value of the restoration work itself.
Null Hypothesis: There will be no difference in economic costs
among treatments.
Expected Result: We expect that a higher success rate in establishing
perennial vegetation will be associated with a higher treatment
cost.
Methods: Because the goal of the project is to restore native
perennial vegetation, there is no market value for that vegetation.
It will have value for livestock forage, but also has values for
biodiversity, ecological health, esthetics, and others. We will
use a least cost approach to determine which treatment will lead
to the most economical solution. The least cost approach is used
in those cases where the costs are known, the objective is known,
but the monetary benefits are unknown. Cost data for each treatment
will be gathered for both the actual treatments and from other
sources such as federal agencies to determine what the costs would
be on an operational scale. A multi-period linear programming
model will be developed to determine the least cost alternative
over time given constraints of weed abundance, soil N availability,
and meeting a specified restoration objective.
Null Hypothesis: There will be no economic effect from seeding
into different abundances of weeds.
Expected Result: We expect that there will be a biological relationship
between weed abundance and the success of the seeded native plant
species and that an economically optimal time path can be determined
from that information.
Methods: Data from experiment 1 will be analyzed to develop a
functional relationship with native species success as a function
of cheatgrass density, other weed abundance, and soil N availability.
Once this relationship is known, an economic model will be built
to determine what level of cheatgrass density is optimal. In order
to determine this optimal level, we would need to know the costs
of keeping cheatgrass at that density and the value of the native
species success. Again this creates a problem - what is the value
of the native plant species in and of themselves? There are two
options at this point. The first is to conduct a contingent valuation
study that would estimate how much people are willing to pay for
different levels of native plant species restoration. The second
is to use a threshold analysis and determine what the native plants
would have to be worth to change the optimal solution. The resulting
value estimate for the native plant species is only that amount
that causes the economically optimal solution to be found. It
is not what society would be willing to pay for that level of
good. The actual amount society would be willing to pay may be
either lower or higher. It would then be left up to the decision-maker
as to whether that value was worth the expense.
Null Hypothesis: There will be no effect on Great Basin livestock
ranches from intensively grazing cheatgrass in early spring.
Expected Result: We expect that ranches will increase profits
from intensively grazing cheatgrass rangelands in the spring by
reducing dependence on hay and other stored feeds and increasing
the feed quality during this normally limiting seasonal grazing
period.
Methods: Example ranch models will be developed for different
regions of the Great Basin using existing work. These models are
based on seasonal forage use by the livestock herds. The option
of intensively grazing cheatgrass stands will be added to the
models. Profit maximizing alternatives under different scenarios
will be determined. The reason for doing this is if this is going
to be a viable treatment alternative, livestock owners need to
understand whether it will help or hurt their operations.
Extension initiatives (Glimp, Rasmussen, & Borman)
Results from this research will be provided to agency personnel,
public land managers, policy makers, and other interested individuals
through traditional Extension/outreach methods.
Periodic field tours will be conducted at selected research sites
to keep collaborating scientists, agency personnel, local officials,
county agents, and interested land managers appraised of current
research findings. As research efforts advance, additional funding
will be obtained to establish large-scale demonstration areas
along key public highways, with descriptive signs at pullouts
to showcase successful treatment options.
A publication entitled "Ecology and Management of Invasive
Weeds on Western Rangelands" will be produced and distributed
through campus and county Extension publications offices of the
University of Nevada, Utah State University, and Oregon State
University. An internet website by the same title will be developed,
patterned after currently existing websites on yellow starthistle,
jointed goatgrass, goatsrue, and other troublesome weed species.
The Society for Range Management, the Western Society of Weed
Science, Society for Ecological Restoration, and the Weed Science
Society of America will be encouraged to link this site to their
own websites.
Articles on weed ecology, negative impacts, and management will
be prepared for publication in newspapers, newsletters, and appropriate
trade magazines.
A summary of weed management recommendations will be included
in both the Utah-Montana-Wyoming Weed Management Handbook and
the Pacific Northwest Weed Control Handbook, which are updated
and published cooperatively on an annual or biennial basis by
Extension Weed Specialists in the corresponding states.
County Agricultural Extension Agents in affected areas will be
given an overview of resulting cheatgrass management recommendations
during regular district and/or state training workshops for Extension
staff. In addition, compressed video technology (CD format) will
be used to make data and video images available from all research
and demonstration sites, allowing users to understand regional
differences and impacts.
Research findings will be presented at area and regional weed
management seminars, IPM workshops, and pesticide applicator training
courses offered annually by the Bureau of Land Management, Forest
Service, and other federal and state agencies. Results also will
be presented at annual meetings and conferences of state weed
associations, the Western Society of Weed Science, the Society
for Range Management, and other appropriate conferences.
Opportunities for cost-share grants will be sought as a means
to encourage private landowners to implement effective weed management
techniques developed from this research.
Educational and community initiatives (Call, Markee, &
Doescher)
Several approaches will be used to promote awareness of invasive
weed issues in the Great Basin for K-12 students, undergraduate
students, and the general public.
Many aspects of invasive weed ecology and management, from the
individual plant level to the ecosystem level, can be tied to
K-12 core curricula (science, social studies, math, language arts)
for schools in the states represented in this consortium. As research
advances, 2-day regional workshops will be held for teachers in
weed-impacted areas. Teachers will be given an overview of the
cheatgrass/secondary weed issue and work with scientists and land
managers at research sites and demonstration areas to gain first-hand
knowledge of the ecological, social, and economic aspects of the
issue. Teachers will be provided with a support system to incorporate
this knowledge and experience in the classroom and in local field
settings (monitoring areas impacted and not impacted by cheatgrass
and secondary weeds). Appropriate, existing materials and activities
(Project Learning Tree, Project Wild, Ag in the Classroom, etc.)
will be recommended; and new materials and activities (research
highlights, case studies, compressed videos in CD format, web-based
activities), specific to invasive species issues in the Great
Basin, will be developed. An internet website, described in section
5.2.4, will contain a synopsis of the ecology and management of
rangeland ecosystems in the Great Basin, with an emphasis on cheatgrass
and other invasive weeds and with links to other relevant sites.
The website will also serve as a database management and communication
tool, where students can enter and compare monitoring data, photos,
and historical and cultural information from their area with students
in other areas of the Great Basin. Also via the internet, scientists
and land managers will remain connected throughout the school
year with teachers who have participated in the workshops.
Undergraduate students at colleges and universities in or adjacent
to the Great Basin will have the opportunity to participate in
research and management experiences associated with the program.
Students interested in research aspects of invasive weeds will
select a research project from an advertised list, identify a
faculty advisor, and work with their advisor to develop a brief
proposal. Students whose proposals are selected by a review panel
will be awarded a $4000 mini-grant ($3000 stipend, $500 travel
costs, $500 research expenses) to support the research. With guidance
from faculty advisors, students will conduct the research, interpret
the results, prepare a report, and present their findings to scientists,
land managers and other interested individuals. Students interested
in managerial aspects of invasive weeds and restoration can apply
to a summer workshop/internship program that has been developed
by Utah State University in conjunction with the Bureau of Land
Management and the National Park Service (Oregon State University
and University of Nevada, Reno have recently joined the program).
During this internship, students attend a 2-week workshop that
focuses on BLM land management issues in a particular area, and
then spend the remainder of the summer with the BLM at several
locations in the Great Basin (Ely, Elko, Battle Mountain, and
Carson City, Nevada, and Richfield, Utah). In terms of undergraduate
teaching, compressed video in CD format and web-based case studies
will be made available for undergraduate courses (environmental
science, ecology, natural resource policy and management, economics)
at universities within and beyond the Great Basin.
Research findings from the program, and general information about
the ecology and management of Great Basin rangelands, will be
presented to various publics through different delivery systems.
Regional and national media relationships will be developed through
1-day workshops/field tours during years 2 and 4. Media representatives
will visit research sites, demonstration areas, and weed-impacted
areas, discuss issues with scientists and land managers, and receive
research summaries and background information. The purpose of
these events is to generate interest in invasive species issues
and provide a mechanism for accurate and continued reporting of
these issues to the public, within and beyond the Great Basin.
There is potential to reach the public through newspaper, magazine
and internet articles, TV news reports, and public radio programs.
An in-depth educational insert can be prepared for the Sunday
edition of newspapers in the Great Basin region. Legislators (and/or
staff members) will also be invited to participate in the media
workshops/field tours to increase their awareness of invasive
species issues. The volunteer monitoring and information sharing
activities described above for school classes can also be performed
by other groups in the community, including 4-H, FFA, Boy Scouts/Girl
Scouts, Audubon, and others.
Project Management
Benefits from consortium
Our multi-state, multi-institution consortium to control invasive
weeds and restore native species on Great Basin rangelands provides
the following benefits:
More robust experiments - Typically, smaller grants from a single
institution would not have sufficient resources to conduct experiments
at more than 1 or 2 sites. Hence, these single-institution experiments
would have at best 1 degree of freedom in their statistical analyses.
Our consortium experiments have greater statistical power because
of the 6 sites per main plot factor. Thus, we have the potential
to determine statistically both general patterns over a range
of environmental conditions and fine-scale patterns that are relevant
to specific sites. The net result is a more comprehensive understanding
of the problems, potential solutions, and the constraints imposed
by the environment.
Pooling of expertise - The breadth of expertise, knowledge, and
experience that is represented by our consortium simply does not
exist at any 1 of our institutions. By pooling our expertise,
we gain the critical mass of scientists, managers, and educators
that are needed to tackle the pervasive problems of invasive weeds
on Great Basin rangelands from the many different ecological,
social, and management perspectives needed to resolve the problems.
Comprehensive, linked data sets - The common protocols among sites
coupled with our carefully-coordinated, interdisciplinary studies
provide for both a comprehensive and a comparative examination
of the results. These common, linked data sets provide a strong
basis for statistical analyses and greatly enhance the capability
for economic and ecological modeling.
Efficient use of resources - Many of us as well as our collaborators
have on-going research interests orientated around the control
of cheatgrass on Great Basin rangelands or the restoration of
these rangelands. The studies in this proposal provide a focal
point for our interests and activities, and thereby minimize duplication
of experimental effort. Thus, the knowledge value added by each
participant is relatively greater because each person can focus
more of their resources on increasing knowledge rather than on
performing the experiments. For a similar reason, our studies
will likely attract many more additional collaborators once they
are underway. Furthermore, because data will be collected using
standardized protocols at all sites and usually analyzed by 1
lab, we gain additional efficiency. In an era of severely constrained
funding, our consortium approach increases the efficiency of grant
dollars.
Wide dissemination of knowledge - Given the severity of cheatgrass
invasion on Great Basin rangelands coupled with the associated
problem of secondary weeds, the results and knowledge gained from
our studies must be disseminated to other scientists, managers,
educators, and the general public in a timely manner. Three features
of our consortium facilitate the timely, wide distribution of
knowledge: 1) our close ties with extension personnel, educators,
and federal land management agencies; 2) our public outreach initiatives;
and 3) our sponsorship of workshops and publications.
Management plan
The overall management structure of the consortium along with
the responsibilities of each component is diagrammed at the right.
The overall program goals, objectives, and directions will be
determined by the Project Management Committee, which consists
of the projectís key personnel. Dr. Nowak will take responsibility
for overall project co-ordination and administration and for integrating
the research, extension, education, and outreach initiatives.
Design, implementation, and publication of the experiments and
their associated ecological and economic assessments measurements
will be the responsibility of the Research Committee. Design,
implementation, and publication of extension, education, and public
outreach initiatives will be the responsibility of the Information
& Technology Transfer Committee.
Overall financial management will be provided by the University
of Nevada, Reno business management system with its existing framework
and accounting systems. Transfer of funds and work responsibility
will occur as a series of subcontracts with participating institution.
Each participating institution has a designated Authorized Institutional
Representative (identified on the Form CSREES-661) who is responsible
for negotiation, execution, administration, and reporting of the
subcontract fiscal concerns and a Principal Investigator who is
responsible for negotiation, execution, administration, and reporting
of specific programmatic responsibilities.
Evaluation and monitoring
Project objectives
Criteria to assess the success of meeting the project objectives
include:
Meet the proposed timetable with the proposed funding.
Publish peer-reviewed scientific papers, extension bulletins,
educational materials, and general brochures that are based on
the proposed studies.
Present the studies at scientific meetings, public forums, workshops,
symposia, and classrooms.
Develop human resources through training of technicians, undergraduate
and graduate students, and postdoctorates.
Project administration
Criteria to assess the success of project administration include:
Meet all project objectives within the proposed time frame with
the proposed funding.
Facilitate the exchange and use of data among project participants.
Create and maintain web sites, link our web sites to related web
sites, and develop web-based tools that are useful for scientists,
managers, educators, and the public.
Integrate the results using statistical and modeling tools.
Sponsor the following workshops:
Measurements and Monitoring Workshop (late winter, 2002). This
workshop will examine the most appropriate techniques to measure
and monitor the ecological processes in Section 5.2.2. Although
a major objective is to train all our personnel so that we use
common techniques and protocols, the workshop likely would interest
other agency and university personnel. The major product would
be a loose-leaf binder publication of Standard Operating Procedures
(SOPís) that would also be accessible as PDF documents
through our web sites.
Education and Public Outreach Workshop (summer 2004). The primary
purpose will be to examine techniques for us (agency personnel,
students, and esp. university professors) to effectively educate
and connect with the general public and other target audiences.
Although we anticipate that this would be a stand-alone workshop,
we will explore sponsoring a workshop in conjunction with a national
societyís annual meeting.
Publish a restoration handbook in a loose-leaf, binder format
targeted for use by land managers. The handbook and updates could
also be downloaded from a web site maintained by the Nevada Agricultural
Experiment Station.
To ensure stability and support beyond the duration of the grant,
the consortium will: 1) pursue the creation of a western regional
project on cheatgrass; and 2) co-ordinate with and support existing
or planned activities such as the BLM Great Basin Restoration
Initiative, WCC-21 (Revegetation and Stabilization of Deteriorated
and Altered Lands), the Joint Fire Science Program, and the Alliance
for Natural Resource Research, Education, and Management in the
Northern Rocky Mountains (aka "Northern Alliance").
Key personnel and collaborative arrangements
Table 1. Summary of responsibilities for personnel & collaborators.
Responsibility Key personnel Collaborators
Project management & coordination Nowak
Project Management Committee Seed & population ecology Pyke,
Chambers & Schupp
Community ecology Tausch, Nowak
Competition & ecophysiology Doescher, Svejcar
Soil ecology Blank, Hilty, Johnson, Monaco, & Norton
Competition screening trials Ogle, Jones
Resource economics Tanaka, McCoy
Restoration ecology& technology Pellant, Call & Perryman
Extension initiative Glimp, Rasmussen & Borman
Education & community Initiatives Call, Doescher & Markee
A summary of the key personnel and collaborators involved with
this project are indicated in Table 1. Specific responsibilities
for each person (or group) also have been identified in sections
of the proposal.
Relevance and Significance
The sagebrush-steppe ecosystem in the Great Basin is changing
at an alarming pace from a network of dynamic plant communities
that support a diversity of plants and animals to a wildland fire
- annual grass cycle system largely dominated by the invasive
weed cheatgrass. We know that this loss of native habitat is not
reversible without active restoration efforts, yet we lack definitive
guidelines to direct the restoration efforts and to plan the appropriate
restoration strategy. The ecological consequences of this change
are striking: loss of wildlife species, unstable watersheds with
degraded water quality, less forage for wild horses, reduced livestock
grazing, and increased invasions of other noxious weeds. And social
and economic impacts are apparent: more dangerous and costly wildfires,
fewer recreation opportunities, lost income from tourism (hunting,
fishing, camping), and reduction in the livestock-ranching industry
that is the heart of many rural communities (USDI 1999). Finally,
the problem is acute: approximately 50% of the 45 million hectares
of Great Basin sagebrush-steppe communities has been converted
to invasive weeds or is likely to convert to invasive weeds after
the next wildfire (West 1999).
Our holistic systems approach that integrates research, education,
and outreach is best suited to address the problems of controlling
invasive weeds and restoring native plant diversity on Great Basin
Rangelands. Our careful examination of ecological and environmental
processes takes a scientific, problem-solving approach to determine
strategies of controlling invasive weeds and restoring native
plants. Our concomitant economic assessment provides an economic
basis for choosing the appropriate management techniques and for
evaluating the risks associated with non-native weed invasion.
Our extension and educational initiatives will not only provide
managers with timely information, but also increase public awareness
of both the magnitude and complexity of the problem and its solutions.
Ultimately, our project will provide solutions to critical land
management issues that are shared by all who own or use Great
Basin rangelands.
Time Table
Year 1 Year 2 Year 3 Year 4
F W S S F W S S F W S S F W S S
Competition experiments
A. Competition screening trials
Characterize study sites XXXX
Prepare plots & apply OUST XX XX
Seed X X
Measurements X XXXX X XXXX
B. Competition mechanisms experiment
Prepare plots & apply OUST XX
Seed X
Measurements X XXXX X XXXX
Restoration experiment
Prepare plots XX
Apply cheatgrass control methods
Herbicide XX
Grazing XX
Fire XX XX XX
Seed cover crop XX
Seed native plant mixes XX
Measurements X XXXX X XXXX
Science workshops and symposia
Measurements and Monitoring Workshop X
Education and Public Outreach Workshop X
4 Educational workshops
Information specialist workshops/field tours XX XX
Media workshops/field tours XX
Teacher workshops XX
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================UPDATE==================
FROM http://cris.csrees.usda.gov/ - November 14, 2005
ACCESSION NO: 0190233 SUBFILE: CRIS
PROJ NO: NEV052JX AGENCY: CSREES NEV
PROJ TYPE: OTHER GRANTS PROJ STATUS: EXTENDED
CONTRACT/GRANT/AGREEMENT NO: 2001-52103-11322 PROPOSAL NO:
2001-04279
START: 15 SEP 2001 TERM: 14 SEP 2006 FY: 2004 GRANT YR: 2001
GRANT AMT: $2,918,000
INVESTIGATOR: Nowak, R. S.; Chambers, J. C.; Blank, R. R.
PERFORMING INSTITUTION:
NATURAL RESOURCES & ENVIRONMENTAL SCIENCES
UNIVERSITY OF NEVADA
RENO, NEVADA 89557
INTEGRATED RESTORATION STRATEGIES TOWARDS WEED CONTROL ON
WESTERN
RANGELANDS
NON-TECHNICAL SUMMARY: Cheatgrass is a non-native invasive
plant that is having profound
impacts on western rangelands. Our overall goal is to identify
concepts and management strategies
to control the spreading dominance of cheatgrass and other weeds
on Great Basin rangelands and
to restore native species and increase biodiversity.
OBJECTIVES: Overall Goal is to identify the necessary concepts
and management strategies to
control the spreading dominance of cheatgrass and other weeds
on Great Basin rangelands and to
restore native species and increase biodiversity. Supporting Objectives
are:
1. Conduct a series of common experiments across the Great Basin
that are designed to test management techniques for
controlling cheatgrass and other weeds, establishing native plant
communities, and restoring
ecosystem structure and function while reducing the high cost
of current restoration efforts.
2. Provide a sound ecological understanding of why cheatgrass
control and native species restoration
techniques succeed or fail.
3. Develop conceptual and economic bases for choosing appropriate management techniques for the range of conditions that exist within the Great Basin.
4. Use active partnerships among governmental agencies, universities,
cooperative extension, and land managers
to convey knowledge of the processes, techniques, and results
to ranchers and other rangeland
professionals.
5. Use partnerships with educators to increase student and public awareness of invasive species issues and to develop educational tools that convey solutions to invasive species and native plant restoration problems.
APPROACH: We will implement 2 core experiments that include
a series of ecological process
studies (i.e. population ecology, community ecology, etc.) and
are complemented by economic
assessments, educational development, and outreach initiatives.
The first experiment will be replicated across a 4-state area that encompasses the range of environmental conditions typical for rangelands prone to cheatgrass invasion. The second experiment will be conducted at a single study site. Both experiments use a split-plot experimental design with the main plot factor as weed abundance, with weed abundance varying from:
1) diverse native vegetation with low cheatgrass abundance in the understory; to
2) cheatgrass as the dominant species but few secondary weeds;
to
3) cheatgrass dominant and active invasion by secondary weeds.
The first experiment investigates if
the competitive interactions between cheatgrass and native species
change with weed abundance or
with soil N availability.
Results from this experiment will indicate:
1) if weed abundance or soil N availability alters cheatgrass growth and thus its competitive advantage;
2) which native species are more competitive with cheatgrass under these different environmental conditions; and
3) the underlying ecological mechanisms for the observed results.
The second experiment investigates if
the effectiveness of 3 different restoration treatments changes
with weed abundance.
Two of the restoration techniques (a prescribed fire and
a prescribed grazing treatment) are targeted at reducing the cheatgrass
seed bank, whereas the third investigates if more competitive
native species
(identified in the first experiment) further enhance cheatgrass
control. Results from this second
experiment will indicate:
1) if prescribed management treatments are capable of reducing either the cheatgrass seed bank or soil N availability, and thus enhance the establishment of native species;
2) if restoration strategies that incorporate a transition
community of competitive species have greater
success;
3) the extent that weed abundance influences the control of cheatgrass and establishment of natives; and
4) the underlying ecological mechanisms for the observed results. Although our focus is primarily cheatgrass, we will also quantify effects on perennial species as well as secondary weeds.
PROGRESS: 2004/01 TO 2004/12
During the 2004 calendar year, the following tasks have been
completed:
(1) Data and samples have been collected from Experiments 1 and
2 throughout the growing season from 8 study sites located across
the 4 states of Idaho, Nevada, Oregon, and Utah. Samples have
been processed, and preliminary data analyses were conducted.
Results were presented at a meeting in December that was attended
by state and federal agency personnel. Preliminary results revealed
that
(a) herbicide treatments negatively affected cheatgrass density and positively affected native plant density;
(b) plant performance within a species varied considerably,
but a number of native plant varieties for some
grass species did almost as well as the crested wheatgrass hybrid;
(c) sites that typically have lower precipitation had higher soil biological crust cover;
(d) application of sugar greatly decreased soil nitrate availability, and cheatgrass seed production and plant size was also significantly reduced by sugar treatments;
(e) increased seeding rates increased plant density, but not proportionally; and
(f) performance of secondary weeds (medusahead, skeletonweed,
squarose knapweed) to different
treatments (+/- cheatgrass, +/- sugar) did not vary in a consistent
manner, suggesting very complex
ecological interactions among cheatgrass, secondary weeds, and
native species.
Other completed tasks include:
(2) Preparations were made for the repeated trials of Experiments 1 and 2, which included herbicide treatments during the spring; cleaning and testing of seed collected in the previous fall; and seeding the second set of replicate plots for Experiments 1 and 2 during the fall at each of the 8 study sites in the 4 cooperating states.
(3) Modifications to the rangeland drill were completed to improve placement and burial of seed.
(4) The study area for Experiment 3 was cleared for use by BLM, and then the study site was prepared, initial vegetation characterized, and fall seeding of the sterile annual hybrid was made to initiate the seed-burn-seed treatment.
(5) Field tours with ranchers, state and federal agency personnel, and NGO's were conducted.
IMPACT: 2004/01 TO 2004/12
We expect to identify:
(1) If any of 25 readily-available, native plant materials will compete effectively with cheatgrass and other secondary weeds, and hence may be used as a transition stage during revegetation.
(2) If the competitive interactions between cheatgrass and 6 native species change with soil N availability.
(3) If a mix of native species that differ in growth form, rooting characteristics, and phenology is a viable method to sequester soil resources.
(4) Determine the effectiveness of 4 different restoration
treatments, two that are targeted at reducing the cheatgrass seedbank
(prescribed fire and prescribed grazing treatments), a third that
examines if an annual cover crop can
be used to tie up soil N, and a fourth that investigates if a
competitive native species (identified in
earlier studies) further enhance cheatgrass control.
PUBLICATIONS: 2004/01 TO 2004/12
No publications reported this period
PROJECT CONTACT:
Name: Nowak, R. S.
Phone: 775-784-1656
Fax: 775-784-4789
Email: nowak@cabnr.unr.edu
===============================
UPDATE DECEMBER
23, 2006:
Location of test plot sites (from an email from Dr. Novak)---
1) Approximate latitudes and longitudes for plots that you
are inquiring
about are as follows:
One site near N40° W112°
One site near N40° W113°
Two sites near N41° W117°
Two sites near N43° W116°
Two sites near N44° W117°
===============================
Updated December 20, 2022 - Go to The Reveg Edge website