Western Rangelands Research Articles

Improving Drought Preparedness Among Utah Cattle Ranchers

Because drought impacts are accelerating due to climate change, drought preparedness on western rangelands matters now more than ever. Range professionals perceive, however, that many Utah ranchers remain ill-equipped for drought. The main research objective was to determine why ranchers often don't adopt recommended drought-mitigation tactics. Another objective was to clarify how grazing is managed during drought on federal lands. Fourteen tactics studied included management of water, forage, herds, and finances and access to information and government programs. Data collection included surveys of 429 ranchers and interviews of seven federal employees. Data analysis used descriptive statistics and logistic regression. Results indicated that 3,133 non-adoption decisions were heavily dominated by the perceived incompatibility between tactics and operational needs; producer situations may often be misunderstood by experts. Weather forecasting tools were typically regarded by ranchers as “too complex,” while Extension information was often viewed as “not useful.” Factors promoting drought preparedness included having a strong livestock-business orientation or a drought-planning mentality. Factors hindering drought preparedness were dominated by advancing rancher age. Grazing permittees benefit from federal drought early-warning systems, yet herd adjustments on allotments were rare during the 2019 drought, pushing forage utilization to the limits. While challenges appear daunting, there are opportunities to enhance drought preparedness, prominently including creative efforts to promote more education and mentoring on operational drought management. Comprehensive, user-friendly drought websites remain rare, yet they can be vital hubs for stakeholders. Such websites must meet diverse communication needs including a greater focus on information requirements of seniors. Drought policies for ranchers should: (1) Eliminate perverse incentives that foster inappropriate risk taking; (2) reward pro-active, risk-management behaviors; and (3) facilitate recruitment of a younger, innovative cohort of new producers. Updating federal management plans could support grazing adjustments that incorporate more grass banking. Unified drought-response guidelines could harmonize agency approaches.

Comparative genomics of the sheep Tas2r repertoire to cattle, goat, human, dog, and mice

Type two taste receptors (Tas2r) are the only taste receptors that distinguish bitter-tasting compounds. Human Tas2r genes have been extensively studied and have been associated with dietary preferences, health, substance dependence, and other diseases. Sheep are an important livestock species known for grazing vast rangelands with variable ecology and plant communities. However, the limited work related to Tas2r gene repertoires in the reference genomes of grazing animals creates a challenge for understanding how these genes influence diet selection preferences. Tas2r genes typically cluster on two regions of the genome. In the second cluster of the sheep (OAR_rambouillet_1.0), goat (ARS1), and cattle (ARS-UCD1.2) reference genomes, there are six, nine, and two Tas2r genes that were not annotated, respectively. Comparative genomic strategies were used to cross-reference sheep Tas2r genes in cattle, goat, human, dog, and mice for the proposed annotations. A nucleotide similarity comparison of the whole Tas2r repertoires for the three grazing species suggested that goat and cattle are similar to sheep (≥ 95.5% and ≥ 91.9% similarity, respectively). Several Tas2r genes found in sheep, cattle, and goat are likely not found in human, dog, or mice and may be reserved to ruminants or animals of similar feeding ecology. Using a comparative genomics approach, this paper proposes annotations for sheep, cattle, and goat Tas2r genes. Further research is needed to better understand how Tas2r genes may influence diet selection in grazing ruminant species, which could provide more insight into management of western rangelands through grazing strategies.

Control of Pest Grasshoppers in North America.

Simple SummaryGrasshoppers (Orthoptera: Acrididae) population outbreaks occur frequently and consume damaging amounts of livestock forage and crops on millions of hectares of the western USA. The main method of controlling grasshopper outbreaks there consists of aerially applied spray with chemical insecticides. Although it is relatively cheap, fast, and efficient, broad spectrum insecticides can pose a threat serious risks to human health, and non-target organism populations which impacts the environment. As an alternative, the use biological control organisms more specific to pest grasshoppers is a less environmentally hazardous alternative to traditional, synthetic insecticides. This paper reviews the many different (viral, bacterial, fungal) insect pathogens and application methods that have been tested as alternatives to synthetic insecticide sprays to manage pest grasshopper populations.Grasshoppers (Orthoptera: Acrididae) frequently inflict damage on millions of hectares of western rangelands and crops. The main method of controlling grasshopper outbreaks consists of covering their infestations with chemical insecticides. Although it is relatively cheap, fast, and efficient, chemical control bears serious risks to human health, non-target organisms, and the environment. To overcome this challenge, biological control is a less environmentally hazardous alternative to traditional, synthetic insecticides. This paper reviews strategies that could be used as effective ways to control such pests with a special focus on effective bait formulations that might provide a key model in developing biological control strategies for the grasshopper population.

Ranchers and Beavers: Understanding The Human Dimensions of Beaver-Related Stream Restoration on Western Rangelands

The past decade has seen a rapid rise in beaver-related stream restoration (BRR) using beavers and beaver dams (real or artificial) as a tool. Potential benefits of this low-cost, nature-based restoration approach include restoring aquatic and riparian habitat and recovering of threatened species dependent on it, improving water availability and stream flow regulation, reducing erosion and stream incision, and supporting climate change adaptation. Although the ecological restoration literature acknowledges the importance of addressing the human dimensions of restoration, there is a gap regarding the human dimensions of BRR. To help fill this gap we examined six projects involving riparian revegetation or artificial beaver dams to identify central elements of a supportive social environment for BRR on western rangelands. Our research questions examined how beavers, beaver dams, and BRR affect ranching operations and how ranchers view them; the policy context for BRR; and how BRR practitioners, regulatory agencies, ranchers, and partners work together for successful BRR. We synthesized our findings across cases and identified six social factors important for BRR: 1) ranchers who perceive the benefits of beavers, beaver dams, and BRR to outweigh the drawbacks; 2) education and assistance to help landowners adopt nonlethal mitigation techniques for nuisance beavers; 3) grazing practices compatible with BRR; 4) low harvest pressure on beavers; 5) a regulatory environment that enables experimentation, flexibility, and adaptive management; and 6) proponents, ranchers, and partners willing to take risks, innovate, be flexible, and stay committed.

A Multi-Scale Approach to Predict the Fractional Cover of Medusahead (Taeniatherum Caput-Medusae)

Medusahead is an aggressive, winter annual that is of dire concern for the health and sustainability of western rangelands in the United States. Medusahead reduces plant diversity, alters ecosystem function, and reduces carrying capacities for both livestock and wildlife. The species has competitive advantages over cheatgrass and native grasses that causes an increased amount of fine fuels deposited on western rangelands. The Channeled Scablands of eastern Washington in the United States represent a typical example of a region being challenged by the expansion of this weed. The costs of the invasion are high and financial constraints can limit successful management. Managers need the ability to identify medusahead across entire landscapes, so they can work towards effective and efficient management approaches. Remote sensing offers the ability to measure vegetation cover at large spatial scales, which can lead to a better understanding of the invasive characteristics of problematic species like medusahead. For instance, research has been successful in creating large-scale distribution maps of cheatgrass over western rangelands. Many applications rely on the phenological characteristics of a target plant which can present problems in separating two species with similar phenologies (i.e. cheatgrass & medusahead). A medusahead-specific map gives managers the flexibility to prioritize and direct management needs when attempting to control the spread of medusahead into non-invaded areas. This study integrated GPS acquired field locations from three study sites (Sites S, C, & N) and imagery from two remote sensing platforms (1-m aerial imagery & 30-m Landsat), to model and predict fractional cover of medusahead over 37,000+ ha of rangelands in the Channeled Scabland region of eastern Washington. Using a multi-scaled approach, this research showed that regression tree algorithms can model the complex spectral response of senesced medusahead using late summer Landsat scenes. The predictive performances resulted in a R2 of 0.80 near the model's training site (Site S) and an average R2 of 0.68 away from the training site (Sites C & N). This research provides a non-phenological approach to produce accurate large-scale, distribution maps of medusahead which can aid land managers who are challenged by its invasion.

Measuring Height Characteristics of Sagebrush (Artemisia sp.) Using Imagery Derived from Small Unmanned Aerial Systems (sUAS)

In situ measurements of sagebrush have traditionally been expensive and time consuming. Currently, improvements in small Unmanned Aerial Systems (sUAS) technology can be used to quantify sagebrush morphology and community structure with high resolution imagery on western rangelands, especially in sensitive habitat of the Greater sage-grouse (Centrocercus urophasianus). The emergence of photogrammetry algorithms to generate 3D point clouds from true color imagery can potentially increase the efficiency and accuracy of measuring shrub height in sage-grouse habitat. Our objective was to determine optimal parameters for measuring sagebrush height including flight altitude, single- vs. double- pass, and continuous vs. pause features. We acquired imagery using a DJI Mavic Pro 2 multi-rotor Unmanned Aerial Vehicle (UAV) equipped with an RGB camera, flown at 30.5, 45, 75, and 120 m and implementing single-pass and double-pass methods, using continuous flight and paused flight for each photo method. We generated a Digital Surface Model (DSM) from which we derived plant height, and then performed an accuracy assessment using on the ground measurements taken at the time of flight. We found high correlation between field measured heights and estimated heights, with a mean difference of approximately 10 cm (SE = 0.4 cm) and little variability in accuracy between flights with different heights and other parameters after statistical correction using linear regression. We conclude that higher altitude flights using a single-pass method are optimal to measure sagebrush height due to lower requirements in data storage and processing time.

Western Ranchers’ Perspectives on Enablers and Constraints to Flood Irrigation

Flood irrigation on western rangelands is important for diverse social and ecological reasons, providing forage for many agricultural operations and maintaining many critical wetlands across the region. However, recent debate over the efficiency of flood irrigation and resulting transition to other “more efficient” types of irrigation has put many of the working wet meadows sustained by flood irrigation at risk. As the sustainability of these landscapes is primarily dependent on ranchers’ management decisions, we sought to gain a deeper understanding of factors influencing ranchers who flood irrigate and how these factors interrelate. We applied the Community Capitals Framework to explore what considerations act as enablers and constraints to maintaining flood irrigation and to evaluate the role of each type of capital in enabling and constraining the coproduction of working wet meadows for ranchers and the environment. Our qualitative analysis of facilitated workshop transcripts and observation notes from two study areas within the Intermountain West showed that ranchers perceived constraining and enabling factors of flood irrigation related to all seven types of community capitals: natural, financial, built, cultural, human, social, and political. The irrigation methods used by ranchers were heavily influenced by environmental components of the landscape rather than reflecting a choice among alternative methods. Other prominent enablers included a commitment toward maintaining the natural history of the landscape and the ranching lifestyle. Primary constraints included the impact of public misperception and the ability to pass their operation on to the next generation. Ranchers weighed multiple considerations simultaneously in a holistic, community-scale approach to management decisions and described how diverse enablers and constraints interacted to determine the viability of flood irrigation and ranching. These results indicate rancher decisions are driven by complex social-ecological considerations and demonstrate the importance of each capital type to rangeland conservation.

PSX-42 Characterization of the effects of high selenium feed on spermatogenesis in rams

Abstract Selenium (Se) is an essential element that is required by animals to maximize health and production. Some western rangelands contain alkaline soils that are naturally high in Se while others have been contaminated with elevated concentrations of bioavailable Se. Anecdotal evidence of poor reproductive efficiency has been reported on some seleniferous ranges. In order to determine the effects of high Se feeds on spermatogenesis, mature rams were fed alfalfa pellets containing 0.1, 7.5, 15, or 25 ppm Se. Desired Se concentrations were achieved by mixing western aster containing approximately 3,000 ppm Se with alfalfa. Pellets were fed at 3% of body weight for twelve weeks during the breeding season. Semen and blood samples were collected weekly and semen viability, motility, and morphology were evaluated. After twelve weeks of being fed high Se pellets, one testicle from each ram was surgically removed for morphometric and histological evaluation. The rams were then fed a control alfalfa pellet during an eight week recovery period while monitoring and collection of samples continued. At the conclusion of the recovery period the second testicle was surgically removed for analysis. None of the rams demonstrated any visible clinical signs of chronic Se poisoning during the study. Rams fed the high Se-containing alfalfa pellet had a decrease in sperm motility and an increase in the percentage of abnormal sperm. Within several weeks of beginning the recovery period, the negative side effects were reversed. Initial histological surveys suggest minimal histologic changes. This is supported by the rapid recovery of spermatic motility which suggests a maturation defect and not a change in spermatogenesis. These findings indicate that in sheep, subclinical Se intoxication does cause significant male reproductive damage. More work is needed to better characterize this damage and to determine its effect on fertility and production.

Weed-Suppressive Bacteria Fail to Control Bromus tectorum Under Field Conditions

The exotic winter annual grass Bromus tectorum L. (downy brome or cheatgrass) infests millions of hectares of western rangelands. Weed-suppressive bacteria (ACK55 and D7 strains of Pseudomonas fluorescens Migula 1895) have been shown to reduce B. tectorum populations in eastern Washington. Unfortunately, outside of Washington, little is known about the efficacy of these or other weed-suppressive bacteria. We used Petri-plate and plant-soil bioassays to test effects of ACK55 and D7 on B. tectorum from Montana and Wyoming. We also tested effects of ACK55 on B. tectorum at six field sites in Montana and one in Wyoming. P. fluorescens reduced B. tectorum germination and root and shoot lengths in Petri-plates but had no effect on plants during growth chamber plant-soil bioassays or field experiments. Bromus arvensis L. (field brome or Japanese brome), a species similar to B. tectorum, was prevalent at two of our sites, and ACK55 was ineffective against B. arvensis as well. Our findings contribute to a growing body of evidence that the ACK55 and D7 strains of P. fluorescens are not reliable tools for controlling B. tectorum in the Northern Great Plains, Central Rocky Mountains, and elsewhere.

Understanding future threats to western rangelands: Modeling the performance of grazing strategies in the face of environmental change

Understanding future threats to western rangelands: Modeling the performance of grazing strategies in the face of environmental change

Evidence for relationship between carbon storage and surface cover characteristics of soil in rangelands

Carbon storage (CS) and consequently carbon sequestration by plants is the most natural and least expensive method for atmospheric CO2 mitigation. Areas with high CS potential should be identified, maintained and subject to investment. CS depends strongly on status of vegetation and soil surface cover characteristics. Therefore, the objectives of the present study was an assessment of the relationship between aridisols CS and characteristics of soil cover in some plant types in western rangelands of Isfahan in Iran. Three different plant types including Scariola orientalis-Astragalus gossypinus, Hordeum fragile-Astragalus gossypinus and Cousinia bachtiarica-Astragalus gossypinus were identified. Then, some sampling plots were placed along the four transects in each plant type, which were placed obliquely to the general and the lateral slope of the region. Plants' characteristics and soil surface characteristics were recorded. The soil samples were taken along transects at depths of 0–20 and 20–75 cm. Soil samples were transferred to the soil laboratory and analysed. The results demonstrated that the soil carbon storge (SCS) is different between three plant types. SCS in Sc. or-As. go, Ho.fr-As. go and Co. ba-As.go plant types were 340, 182 and 173 kg/ha, respectivly. Moreover, there was a positive and significant relationship (R2 = 0.88|0.42, p < 0.01) between coverage and density of shrubby species and soil surface gravel with amount of CS.

Survey of Beaver-related Restoration Practices in Rangeland Streams of the Western USA.

Poor condition of many streams and concerns about future droughts in the arid and semi-arid western USA have motivated novel restoration strategies aimed at accelerating recovery and increasing water resources. Translocation of beavers into formerly occupied habitats, restoration activities encouraging beaver recolonization, and instream structures mimicking the effects of beaver dams are restoration alternatives that have recently gained popularity because of their potential socioeconomic and ecological benefits. However, beaver dams and dam-like structures also harbor a history of social conflict. Hence, we identified a need to assess the use of beaver-related restoration projects in western rangelands to increase awareness andaccountability, and identify gaps in scientific knowledge. We inventoried 97 projects implemented by 32 organizations, most in the last 10 years. We found that beaver-related stream restoration projects undertaken mostly involved the relocation of nuisance beavers. The most common goal was to store water, either with beaver dams or artificial structures. Beavers were often moved without regard to genetics, disease, or potential conflicts with nearby landowners. Few projects included post-implementation monitoring or planned for longer term issues, such as what happens when beavers abandon a site or when beaver dams or structures breach. Human dimensions were rarely considered and water rights and other issues were mostly unresolved or addressed through ad-hoc agreements. We conclude that the practice and implementation of beaver-related restoration has outpaced research on its efficacy and best practices. Further scientific research is necessary, especially research that informs the establishment of clear guidelines for best practices.

Are plant waxes reliable dietary markers for cattle grazing western rangelands?1

Are plant waxes reliable dietary markers for cattle grazing western rangelands?1

Lessons Learned from Bison Restoration Efforts in Utah on Western Rangelands

On the Ground Bison are considered the keystone species of the Great Plains but widespread slaughter led to their near extinction. Utah has two wild, free-ranging herds on public lands managed as wildlife though hunting. Both herds are descended from animals reintroduced to the Henry Mountains in the 1940s and more recently the Book Cliffs in 2008. Key elements for the successful ecological restoration of bison include: Legal designation of bison as wildlife in the state Genetically-pure, disease-free source Large expanses of habitat-they take a lot of room Potential conflicts must be identified and addressed in a transparent manner Mutual purpose and trust with all affected stakeholders is essential; i.e., ask, How can we have both sustainable livestock grazing and a viable bison herd on the unit? Active management to address changing situations and maintain herd size at a sustainable level

Seed Selection by Desert Rodents: Implications for Enhancing Seedling Establishment of Indian Ricegrass (Achnatherum hymenoides)

Abstract. Seeds of many plant species are dispersed by seed-caching rodents that place groups of seeds in superficially buried scatterhoard caches. A case in point is Indian ricegrass (Achnatherum hymenoides), an important forage plant on arid western rangelands for which seedling recruitment comes largely from scatterhoards made by desert heteromyid rodents. A “diversionary seeding” strategy has been attempted for enhancing Indian ricegrass seedling recruitment by deploying commercially available seeds on the soil surface to divert rodents from recovering scatterhoards of Indian ricegrass seeds. The probability of such a passive restoration approach succeeding is likely affected by the relative desirability to rodents of Indian ricegrass seeds versus diversionary seeds. We conducted laboratory experiments to test preferences of Merriam's kangaroo rat (Dipodomys merriami), a primary dispersal agent of Indian ricegrass seeds, for Indian ricegrass seeds versus seeds of 5 diversionary seed candidates. Indian...

Meta-Analysis of Diet Composition and Potential Conflict of Wild Horses with Livestock and Wild Ungulates on Western Rangelands of North America

Wild horse (Equus ferus caballus) management in western North America is an escalating concern for ecological integrity on these landscapes. Identifying potential diet overlap among horses, livestock, and wildlife will inform management decisions to optimize multiple interests. To understand dietary relationships, we conducted a quantitative synthesis of microhistological fecal studies for wild horse, beef cattle (Bos spp.), domestic sheep (Ovis aries), elk (Cervus elaphus), pronghorn (Antilocapra americana), and mule deer (Odocoileus hemionus) diet composition on western rangelands of North America. Our search yielded 60 studies from 14 states, 1 Canadian province, and 2 Mexican states with 392 unique species-season samples. We summarized plant species into graminoid, forb, and browse functional groups. For wild horses, seasonal diet composition means for graminoids (77−89%), forbs (4−15%), and browse (3−10%) did not vary seasonally for any plant group (P ≤ 0.05). Univariate analyses and the calculation of effect sizes corroborated our finding that graminoid composition explained the potential overlap of wild horses with cattle regardless of season, with sheep and elk in the spring, with sheep in the summer, and with elk in the fall and winter. Although data indicate wild horse diets are primarily composed of graminoids, several studies reported unusual, regionally specific shifts in response to winter snow that limited graminoid accessibility, leading to higher browse composition. Season, plant composition, and ungulate assemblage may all influence dietary competition between wild horses and other large ungulate sharing western North American rangelands; however, the low and nonsignificant heterogeneity values at alpha 0.01 for cattle:horse effect size comparisons suggest that cattle and horses respond to regional and seasonal variation similarly—a result not observed for other ungulate:horse comparisons. Our meta-analysis provides a robust data set for evaluations of diet composition for wild horses, livestock, and wildlife, whereas no empirical studies have assessed all species together.

Development of fine-leaved Festuca grass populations identifies genetic resources having improved forage production with potential for wildfire control in the western United States

Drought and heat tolerant fine-leaved fescue (Festuca ssp.) grasses have potential as components in rangeland greenstrips for wildfire control in semi-arid climates, although such grasses have not been evaluated under rangeland conditions. Therefore, 63 geographically diverse Festuca accessions of 11 species were evaluated for vigor, color, and biomass in 2009 and 2010 in North Logan, UT to identify grasses for use in U.S. western rangelands. Sixty-two plants representing eight species were selected in 2009 to intermate for further evaluation. Controlled biparental matings among these selections in 2010 produced 18 populations with sufficient seed to be evaluated with three commercial Festuca checks in replicated trials between 2012 and 2013 at Malta, ID, Blue Creek, UT, and North Logan, UT, where mean annual precipitation is 265, 362, and 484 mm, respectively. Plants were evaluated for color, relative vigor, biomass, seed yield, persistence, and regrowth over 2 years. Generally, four fine-leaved populations (R4S4, R4S6, R4S22, and R4S32) with parents originating from Turkey (F. valesiaca subsp. valesiaca), Russia (F. valesiaca, F. valesiaca subsp. valesiaca), Iran (F. valesiaca), and the U.S. (F. ovina) performed equal to or better than ‘Durar’ or ‘Covar’ checks. In Malta (harshest environment), the performance of these four populations compared to ‘Durar’ was 84–210 % for vigor, 79–90 % for color, 65–562 % for biomass, 64–296 % for seed yield, 92–117 % for persistence, and 164–454 % for regrowth, where R4S22 was superior. AFLP analysis indicated that all four populations were distinct, and that R4S4 and R4S6 grouped near ‘Covar’, R4S22 clustered near ‘Black Sheep’ and ‘Durar’, and R4S32 was genetically unique. These populations exhibit drought tolerance and green leaf color under harsh U.S. western desert conditions that make them amendable for use in greenstrips for wildfire control.

The invasive annual cheatgrass releases more nitrogen than crested wheatgrass through root exudation and senescence.

Plant-soil feedbacks are an important aspect of invasive species success. One type of feedback is alteration of soil nutrient cycling. Cheatgrass invasion in the western USA is associated with increases in plant-available nitrogen (N), but the mechanism for this has not been elucidated. We labeled cheatgrass and crested wheatgrass, a common perennial grass in western rangelands, with (15)N-urea to determine if differences in root exudates and turnover could be a mechanism for increases in soil N. Mesocosms containing plants were either kept moist, or dried out during the final 10days to determine the role of senescence in root N release. Soil N transformation rates were determined using (15)N pool dilution. After 75 days of growth, cheatgrass accumulated 30% more total soil N and organic carbon than crested wheatgrass. Cheatgrass roots released twice as much N as crested wheatgrass roots (0.11 vs. 0.05mgN kg(-1) soil day(-1)) in both soil moisture treatments. This occurred despite lower root abundance (7.0 vs. 17.3g dry root kg(-1) soil) and N concentration (6.0 vs. 7.6gN kg(-1) root) in cheatgrass vs. crested wheatgrass. We propose that increases in soil N pool sizes and transformation rates under cheatgrass are caused by higher rates of root exudation or release of organic matter containing relatively large amounts of labile N. Our results provide the first evidence for the underlying mechanism by which the invasive annual cheatgrass increases N availability and establishes positive plant-soil feedbacks that promote its success in western rangelands.

Germination and Seedling Emergence of Three Semiarid Western North American Legumes

Few seed sources of North American forbs are available for revegetation/restoration of degraded western rangelands adapted to annual precipitation zones less than 300 mm, and those that are available are mainly wildland collected. The amount of time and resources necessary to make wildland collections in quantity results in high seed prices and variable seed quality, such that forbs have been under-represented in rangeland seeding mixes. We have previously identified western prairie clover (Dalea ornata Douglas ex Hook.), Searls’ prairie clover (Dalea searlsiae A. Gray), and basalt milkvetch (Astragalus filipes Torr. ex A. Gray) as native species adapted to low precipitation zones in the western United States for which field-grown seed production would potentially reduce seed costs and increase availability. A series of glasshouse experiments were conducted to determine the effects of scarification, planting depth, and soil composition on germination and seedling emergence of these species. All three species produce hard seeds, and scarification was necessary to increase germination and seedling emergence. Compared with a 6-mm planting depth, a planting depth of 19 mm retarded the rate of emergence for all species but only reduced the total seedling emergence for basalt milkvetch. With seed scarification in sandy soils, prairie clover seedling emergence exceeded 80% while basalt milkvetch was less than 10%. With seed scarification in soils with higher clay content, prairie clover total seedling emergence reduced to 58–70% while basalt milkvetch increased to approximately 30%. Along with enhancing stand establishment in seed production fields, these data will assist land managers in planning for optimal establishment of these species in rangeland revegetation/restoration projects.

Prefire (Preemptive) Management to Decrease Fire-Induced Bunchgrass Mortality and Reduce Reliance on Postfire Seeding

Western rangelands are currently under severe threat from exotic annual grasses. To successfully manage rangelands that are either infested with or susceptible to exotic annual grasses, we must focus on increasing resilience to disturbance and resistance to exotic annual grass invasion. Here, we present a fuel-based model and research framework for Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle & Young) rangelands that focuses on increasing resilience to fire and resistance to exotic annual grasses through the maintenance of perennial bunchgrasses. By maintaining perennial bunchgrass, exotic annual grasses have limited resources, thus decreasing the invasibility of the site. In order for the fuel-based model to be effective in guiding land management practices, research that evaluates the interactions between biotic and abiotic factors that influence fire-induced bunchgrass mortality is needed. Hence, we propose a research framework to identify and fill potential gaps in current scientific knowledge. We also suggest potential research objectives that are necessary to make informed management decisions before wildfire, with a goal to ultimately decreasing our reliance on marginally successful postfire restoration practices through preemptive management strategies.