The objective of the first chapter of this thesis was to determine whether fungicide seed coatings constitute an effective strategy for increasing seedling recruitment in restoration scenarios in the Intermountain West. We tested a mixture of four fungicides that address potential fungal pathogens to bluebunch wheatgrass, a dominant bunchgrass that is commonly used in restoration. Across two sites and three years, we found that the fungicide seed coating increased emergence in five of the six sites and years, with an average increase of 59.1% over the control. There was a strong interaction (P < 0.001) between the effects of fungicide treatment, the year and the site on emergence. This interaction was likely related to the effects of the hydrothermal microsite environment on disease severity. Further research is necessary to fully understand the conditions under which fungicide seed coatings are most likely to be effective. The objectives the second chapter of this thesis were to 1) estimate the effects of golden eagle nest proximity to explosive disturbances on reproductive success given other relevant habitat variables (e.g. indices of topography and vegetation), and 2) determine the relative importance of nest proximity to explosive disturbances as a predictor of golden eagle reproductive success compared to other relevant habitat variables. Reproductive success data were collected from nesting territories within and surrounding land controlled and managed by the US Department of Defense. We fit the reproductive survey data using generalized linear mixed-effects models comprised of unique, hypothesis-based sets of habitat variables. We compared the models using AICc-based model selection processes. Given the best approximating model, we found no evidence that the likelihood of reproductive success was affected by nest proximity to explosive disturbances (P = 0.460). We further found nest proximity to explosive disturbances consistently ranked in the bottom 50% of relative variable importance. These results may indicate golden eagle tolerance or habituation to explosive military tests and trainings. Although the two chapters of this thesis are disjointed, they are loosely unified by the ecological importance of disturbance, invasive species, and restoration within the Great Basin ecoregion.

Globally, mining is vital to human interests, but its practice can cause landscape alteration which may look unnatural or engineered. The reintroduction of native plants to these areas is needed to restore the visual appeal and ecological function back into these altered mine lands. Cercocarpus ledifolius (curl-leaf mountain mahogany) is one desirable native species in the Intermountain West that is prized for its potential to grow on step and rocky hillsides and for the habitat it provides for wildlife. Unfortunately, C. ledifolius does not establish well from seed, which has been attributed to seed dormancy. The first objective of this study was to determine if scarification and gibberellic acid (GA3) treatments improve germination by alleviating seed dormancy. We also aimed to determine if a combination of fungicide and hydrophobic seed coatings increased emergence and establishment of C. ledifolius seedlings in mine overburden by reducing loss from fungal pathogens and premature germination. We found that two treatments, GA3 and GA3 + hydrophobic coatings, improved emergence compared to untreated seed, producing 1.8 (P = 0.0682), and 2.2 (P = 0.0751) more seedlings per meter, respectively. The second objective of this study was to make improvements in the laboratory to treatments explored in the field trial. We found that C. ledifolius seed responded inconsistently to treatments applied in the lab. The 15-minute acid scarified seed in combination with various GA3 seed coatings had significantly higher germination than untreated seed in one trial but had no difference in a second trial. Overall, these results indicate that seed enhancement technologies have the potential to improve C. ledifolius emergence in reclaimed mine lands, but additional research is needed to understand the species' dormancy characteristics better and improve the efficacy of the applied seed treatments.

The sagebrush (Artemisia spp.) steppe is undergoing rapid ecological change. The degradation of sagebrush steppe rangelands has resulted in the listing of more than 350 animals and plants as species of conservation concern. In addition, there has been a decrease in recreational values, reduced forage production, degraded water resources, and an increase in fire frequency. In the sagebrush steppe, success rates for seeding sagebrush after wildfire are notoriously low. Not only are sagebrush seeds hard to sow due to their small size and associated flower parts, but seedlings are exposed to numerous stresses that lowers their survivability. To improve sowing efficiency and reduce the associated stresses to seedling development we use seed enhancement technologies. In Chapter 1, we explain how a rotary seed coater can be used to agglomerate and apply enhancements to Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis) seed. Using a mix of compost and clay we used a rotary seed coater to create small uniform agglomerates that allowed for enhancements to be applied to the seed. Our study demonstrated that agglomerates have no negative effects on seed germination and increased the overall flow of seed. In Chapter 2, we analyzed the addition of the plant hormone abscisic acid (ABA) in seed coatings. This hormone may delay seed germination and allow seedlings to avoid mortality due to over-winter freezing. We determined effects of different concentrations of ABA on total germination and timing of germination. Using a wet-thermal accumulation model, we estimated germination timing of seeds using soil temperature and water potential data for six different sites in the Great Basin. These models illustrate the variation in germination timing across the Great Basin. From our results we proposed the idea of using ABA to create a bet- hedging strategy in seed mixes to increase the probability that some seeds would germinate when conditions are favorable for seedling success.

Planting native species after a major disturbance is a critical tool land managers use to stabilize soils, restore ecosystem processes, and prevent weed invasion. However, within the sagebrush steppe and other arid and semi-arid environments the percentage of sown seeds that produce an adult plant is remarkably low. Applying fertilizers at the time of planting may improve native plant establishment by increasing the ability of the seedlings to cope with environmental stresses. However, traditional fertilizer applications are often economically infeasible and may be counterproductive by encouraging weed invasion. Seed coating technology allows for the efficient application of fertilizers within the microsite of the seeded species. The objective of our research was to determine the optimal rate of fertilizer to apply to the seed to improve seedling emergence and plant growth. We applied a phosphorus (P) rich fertilizer (0.13 g P g-1) to bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Á. Löve) seeds in a rotary coater at rates ranging from 0 to 50 g of fertilizer 100 g-1 seed. Three separate studies were conducted to test germination, biomass, relative growth rate, and tissue nutrient uptake. Study one showed decreasing root and shoot biomass and increasing time to 50% germination as fertilizer rates increased. Study two showed no difference in relative growth rate between the controls and fertilizer treatments. Study three showed no difference in root and shoot biomass or nutrient concentration between treatments except in the lowest fertilizer treatment (10 g fertilizer 100 g-1 seed), which was significantly lower in root and shoot biomass than all other treatments but had higher P tissue concentrations than all other treatments. Collectively these results showed no evidence that a P fertilizer coating could aid in bluebunch wheatgrass seedling establishment. Because bluebunch wheatgrass and similar late-seral plants have evolved with low nutrient requirements they may not be physiologically capable of handling increased nutrient supply, which may explain the results of our studies. Continued studies and fieldwork need to be performed to evaluate the potential of fertilizer seed coatings in restoration efforts.

With many natural landscapes undergoing restoration efforts, there is a growing need for the optimization of direct seeding practices. Seeds planted on wildlands are often consumed by rodents leading to reduced plant establishment. Coating seeds in rodent aversive products may prevent seed predation. We tested ten seed-coating formulations containing products expected to deter rodents, namely: ghost and cayenne pepper powders; essential oils from bergamot, neem, and pine; methyl-nonyl-ketone, anthraquinone, activated carbon, beta-cyclodextrin and a blank coating containing no rodent deterrents to serve as a control treatment. Each treatment was applied to Pseudoroegneria spicata (bluebunch wheatgrass) seeds. These seeds germinated similarly to uncoated control seeds unless the coating contained methyl-nonyl-ketone which reduced germination. Seeds were offered to Ord's kangaroo rats (Dipodomys ordii) that strongly avoided the treatments in favor of uncoated control seeds. Notably, the blank coating, lacking active ingredients, still elicited 99% avoidance. However, these results indicated behavior when alternative food sources are readily available, a scenario rare in nature. To address this, a second feeding experiment was conducted to observe D. ordii's behavior under calorie-restricted conditions. D. ordii were subjected to a fast period and then offered only one treatment. Under these conditions, many subjects chose to consume coated seeds, but to a lesser degree than subjects offered control seeds. Seeds coated in ghost pepper, neem oil, and activated carbon reduced consumption by 47-50%. Given these lab results, we would expect these seed-coatings to increase the establishment of native seeds following the direct seeding of wildlands by deterring rodent seed-predation.

Arid and semi-arid rangelands are important ecosystems that are consistently degraded through disturbances such as wildfires. After such disturbances, the invasion and dominance of annual grasses, like cheatgrass (Bromus tectorum L.), can lead to an overall loss of ecosystem productivity and an increase in fire frequency. To reduce weed dominance, native and introduced perennials species are typically be seeded in the fall. High mortality is seen from these seeded plant communities due to germinated seed being exposed to freezing, drought, fungal pathogens, and other biotic and abiotic stressors during winter months. We utilized wet-thermal accumulation models to first further validate the theory that germination from seeded plant populations occurs during periods of high environmental stress, and then to establish the practicality of abscisic acid seed coatings as a technology that could circumvent winter germination and mortality. In Chapter 1, we developed an excel workbook called Auto-Germ using Visual Basic for Applications, which allows users to estimate field germination timing based on wet-thermal accumulation models and field data. We then used Auto-Germ to model seed germination timing for 10 different species, across 6 years, and 10 Artemisia-steppe sites in the Great Basin of North America. We estimated that for the majority of the species analyzed, a mid to late-winter planting was required on average for the majority of the population to germinate in the spring. This planting time would be logistically difficult for many land managers, due to freezing and/or saturated soil conditions. In Chapter 2, we utilized wet-thermal accumulation models to evaluate the use of abscisic acid (ABA) to delay germination of Pseudoroegneria spicata (Pursh) Á. Löve (perennial native bunchgrass) across 4 years and 6 Artemisia-steppe sites. Germination models estimated that ABA seed treatments typically would delay germination of fall sown seed to late winter or early spring when conditions may be more favorable for plant establishment. Based on these results, we recommend both the use of wetthermal accumulation models as a tool in educating researchers and land managers in knowing when seeding practices should occur, and the further study of ABA seed coatings as a technology that may improve plant establishment of fall sown seeds.

Seed germination during unhospitable environmental conditions can be a major barrier to direct seeding efforts in dryland systems. In the sagebrush steppe, Artemisia tridentata Nutt. ssp. wyomingensis and Artemisia arbuscula are important shrub species that are being used in restoration, but seeding success is highly sporadic due to inter-annual and intra-seasonal weather variability. Altering and expanding the period of germination, as a form of bet-hedging, may improve plant establishment. Our objective was to determine if we could expand the period of germination using plant growth regulators (PGRs) applied in a conglomerated seed coating treatment. In a laboratory study, the seed was either left untreated, conglomerated separately with two concentrations of a germination inhibitor, abscisic acid (ABA), or with two different germination promoters, gibberellic acid (GA3) and 1-Aminocyclopropane carboxylic acid (ACC), a precursor to ethylene. Seeds were incubated in a loam soil at five constant temperatures (5-25 C) for approximately three months. Results indicate that seed treatments with PGRs can delay or speed germination. The greatest response to the seed treatments was observed at 5 C. For example, at this temperature PGRs delayed the time for 25% of the seeds to germinate by a maximum of 35 and 21 d and decreased this time by 5 and 25 d for A. t. ssp. Wyomingensis and A. arbuscula, respectively. Field studies are needed to determine if the bet-hedging strategy developed in this study will increase the likelihood that some seeds will germinate during periods that are more favorable for plant establishment.

The sagebrush steppe is a particularly sensitive ecosystem that is easily disturbed by fires, oil and gas extraction, woody-plant encroachment, and overgrazing. The natural regeneration of native species following a disturbance within this system is typically slow and sporadic, which allows invasive grasses to occupy the landscape. Attempts to assist the recovery of these landscapes through direct seeding is commonly met with poor success rates, particularly in lower elevation, drier sites. Novel seed enhancement technologies and planting techniques that mitigate limiting factors impairing restoration efforts may improve the likelihood of restoring these degraded areas. For chapter 1, we evaluated a solid-matrix priming technique, where bluebunch wheatgrass (Pseudoroegneria spicata) and Lewis flax (Linum lewisii) were primed and then the priming matrix and seed were pelleted together. We evaluated primed seed that had been incorporated into pellets at two field sites against seed that was pelleted but been left unprimed, and untreated seed (control). These three seed treatments were planted in the spring (mid-march) in shallow (2-cm) and deep (15-cm) furrows, in a complete factorial design. We found that primed seeds generally produced higher plant densities than control seed at the beginning of the growing season; however, its influence diminished towards the end of the growing season. We also found that deep furrows increased plant density throughout the growing season and even into the following year. The combination of priming and deep furrows outperformed control seed in shallow furrows in all measured metrics. For chapter 2, we evaluated a seed conglomeration technique for improving Wyoming big sagebrush (Artemisia tridentata ssp. Wyomingensis) emergence and survival under fall and winter plantings. The trial was implemented at five sites across Utah and Nevada in a randomized complete block-split-split plot design, with site, and planting season, comprising the split-plot factors. Each site and season combination was seeded with conglomerated and control seed. We found that in most cases, a fall seeding of Wyoming big sagebrush was either the same or more successful compared to planting on the snow in the winter, which is the current suggested practice. Our results also demonstrated that seed conglomeration produced higher plant densities compared to control seed throughout the growing season. The higher density of plants produced from conglomerates combined with the improved seed delivery provided by the conglomeration technique was estimated to offset the cost in producing conglomerates and reduce overall restoration costs by 41%.