The availability of water is a limiting resource for many wildlife species in arid and semi- arid environments. Free water is essential for critical life stages for numerous species, including migration, reproduction, survival, and habitat selection. Riparian areas in the desert occur relatively infrequently, but support a disproportionally large percentage of plant and wildlife species found in arid environments. Our study covered two aspects of water use in the west desert of Utah. The first was assessing the impacts of nonnative ungulates (specifically feral horses and cattle) on natural springs, and how they influenced water quality, vegetation, and wildlife diversity at those springs. We found that these ungulates reduced plant cover and plant species richness at our sites. Additionally, we found that the number of plant species positively correlated with wildlife diversity. This indicates that further management of these nonnative ungulates may be warranted. In our second chapter we investigate how Golden Eagles (Aquila chrysaetos) use water by quantifying seasonal use, behavior, and testing a hypothesis that a ‘runway’ with drop in elevation is needed for eagles to have a quick exit. We found that eagle use of water resources was strongly concentrated in the summer months during the hottest temperatures. Adult birds used water features more often than younger birds. The most common behavior exhibited at water features was drinking, followed by bathing and preening. We found that there was a positive relationship between the number of visits and the maximum slope at each site, supporting the idea that the ‘runway’ is not required but is preferred at water sources. Overall, our results indicated that Golden Eagles use water regularly in arid environments, particularly during summer months. This research provides insight into how species are using desert riparian areas and how these species and habitats should be managed in future decades.

Food insecurity is one of the biggest challenges facing American society today. Over 13.7 million US households were food insecure in the year 2019 and 19 million Americans lived in food deserts in the year 2015 (USDA, 2020, 2017). Despite food insecurities affecting communities in every corner of the country, there is a dearth of research on food security and food deserts. Therefore, the main objectives of this study are 1) to identify underlying neighborhood characteristics that predict the communities at higher nutritional risk, 2) to analyze the impacts of household characteristics on household food insecurity, and 3) to examine the combined influences of both household and neighborhood characteristics on household food insecurity. Through exploratory factor analysis, eleven socioeconomic characteristics of neighborhoods were systematically grouped into two factors. The first factor represented the neighborhoods with lower socioeconomic status and the second factor represented the declining neighborhoods. Both neighborhoods are less attractive to the big retail stores economically (Bonanno, 2012), and are sometimes subject to malpractice like supermarket redlining (Eisenhauer, 2001).The food desert vulnerability index (FDVI) was created by ranking the variables of factor 1 and factor 2, and the ranking was based on percentiles. This index identified the census tracts of the Southern United States, Maine, Oregon, New Mexico, and Arizona as the socioeconomically vulnerable neighborhoods thereby their possibility of being food deserts. Additionally, analysis of the effect of household characteristics using the regression models suggested that households that were large, minorities, single-parent, male-headed, and lived in the metros, and Midwestern and Southern regions were food insecure. Combined assessment of household and neighborhood characteristics using hierarchical linear modeling revealed that only 2.03 percent of the variance in the household food security score was attributable to differences between counties, thereby implying household food security was mostly dependent on the household’s characteristics. The major limitation of this study is that it does not incorporate the cross-sectional variations in food prices, the role of social capital, and the analysis of the food environment to assess household food insecurity. Research examining the influence of these aspects on household food security would be beneficial.

Microbial communities play critical roles in biogeochemical cycles of aquatic and terrestrial ecosystems, but studies of soil microbial communities have been limited by the diversity and complexity found in most ecosystems. Here we report on work investigating the functional diversity of microbial mat and underlying soil communities in the McMurdo Dry Valleys of Antarctica across a gradient of phosphorus availability on glacial tills of distinct age and mineral composition in Taylor Valley, Antarctica. Microbial mat and soil DNA were extracted and sequenced on an Illumina NextSeq500 in a 150 bp paired end format. Raw sequences were uploaded to the MG-RAST server for processing and annotation. Community taxonomic and functional annotation were determined using the RefSeq and SEED Subsystem databases, respectively. The results revealed significant variation in microbial mat community taxonomic composition between the two tills, strongly associated with visual assessment of mat morphology, e.g., "black" and "orange" mats, and soil N:P ratios. The underlying soil microbial communities did not exhibit significant differences in diversity between the two tills, but community composition varied significantly across gradients of soil chemistry, particularly extractable-phosphate content even within tills. The relative abundance of biogeochemistry-relevant pathways determined from the SEED database varied amongst soil microbial communities between the two tills. For example, microbial mat communities exhibited significant variation in the relative abundance of key nitrogen and phosphorus metabolism associated genes strongly associated with the underlying soil N:P. These results suggest that spatial variation in geochemistry influences the distribution and activity of microbial mats, but that the microbial mats themselves also exert a significant homogenizing effect on the underlying soil communities and some of the key biogeochemical processes they facilitate. / Master of Science / Microbial communities play critical roles in the processes of aquatic and terrestrial ecosystems. Still, studies of soil microbial communities have been limited by the complex nature of the ecosystems we study. This study examined the diversity of microbial communities in the McMurdo Dry Valleys of Antarctica, specifically looking at how different levels of phosphorus availability in the soil affected microbial function. We used DNA sequencing and databases to determine the taxonomic and functional makeup of these communities. We found that while the microbial mat communities varied significantly based on soil chemistry and appearance, the underlying soil microbial communities did not. We also found evidence suggesting that the microbial mats played a role in regulating some of the key ecosystem processes in the soil. Overall, this study sheds light on how microbial communities are impacted by their environment and how they, in turn, impact their surroundings.

Investigating ecological questions at the scale of individual organisms is necessary to understand and predict the biological consequences of environmental conditions. For small organisms this can be challenging because we need tools with the appropriate accuracy and resolution to record and quantify their ecological interactions. Unfortunately, many of our existing tools are only appropriate for medium to large organisms or those that are wide ranging, inhibiting our ability to investigate the ecology of small organisms at fine scales. In Chapter 1, I tested a novel workflow for recording animal movements at very fine spatial and temporal scales. The workflow combined direct observation and the mapping of locations onto high-resolution uncrewed aerial vehicle (UAV) imagery loaded on hand-held digital devices. Observers identified landscape features they recognized in the imagery and estimated positions relative to those features. I found this approach was approximately twice as accurate as consumer-grade GPS devices with a mean and median error of 0.75 m and 0.30 m, respectively. I also found that performance varied across landscape features, with accuracy highest in areas that had more visual landmarks for observers to use as reference points. In addition to sub-meter accuracy, this method was cost-effective and practical, requiring no bulky equipment and allowing observers to easily record locations away from their own location. While this workflow could be used to record locations in a variety of situations, it will be most cost-effective when also using high-resolution environmental data from a UAV. In Chapter 2, I used the workflow described in Chapter 1 to investigate blunt-nosed leopard lizard (Gambelia sila) thermoregulation at fine-scales. Recent research has suggested that the spatial distribution of temperatures is important to consider for ectotherm thermoregulation, but this work has been limited to simple artificial environments. My goal was to investigate this idea in a complex natural system for the first time. I tracked lizard movement and body temperatures at a desert site from May to July 2021. I used machine learning to combine high-resolution environmental data from a UAV with microclimate temperature data to create a model of the spatial distribution of environmental temperatures over time. I found that including information about the spatial distribution of temperatures improved the models of lizard thermoregulatory accuracy and movement rate. Because these response variables are important aspects of ectotherm energetics, this suggests that the spatial distribution of temperatures may be an important, but often overlooked, component of habitat quality. Going forward, identifying better methods to quantify the spatial distribution of temperatures would provide insights into the specific responses of ectotherms to different spatial distributions. In this work I used recent technological advances in UAVs to investigate ecological questions at the scale of a small organism. The methods developed here provide insights into the importance of the spatial distribution of temperatures for a small ectotherm. Further efforts to develop, test and utilize tools for fine-scale ecological research will advance our ability to understand species’ interactions with current conditions and predict their responses to future changes.

Atriplex is a genus in the Chenopodiaceae, the perennial members of which are ecologically important in western North America. Seventeen species and one subspecies of perennial Atriplex occur in Utah and the northern deserts. Three of these species and the subspecies were described by the writer in a recent publication as a result of extensive field work leading to this study. These are A. welshii, A. navajoensis, A. bonnevillensis, and A. cuneata ssp. introgressa. This study is an investigation of the systematics and phytogeography of the perennial Atriplex in Utah and the northern deserts, with emphasis on the A. gardneri and A. garrettii groups. Since the publication of the Phylogenetic Method in Taxonomy (Hall and Clements, 1923) little systematic work has been done on North American Atriplex. The results of this study indicate that considerable reorganization of taxa occurring within the northern deserts is necessary. The five species formerly classified within A. "nuttallii" Wats. are considered specifically distinct because they are not only discrete morphologically, but soil analysis indicate they have differing edaphic requirements and do not interbreed when sympatric. Nine hybrids are fully discussed. Of these, only one was previously recognized as a hybrid. In addition, one species (A. bonnevillensis) and the subspecies (A. cuneata ssp. introgressa) were found to be of hybrid origin. Scatter diagram analyses are included for six of these hybrids and their parents and the two taxa of hybrid origin. Each taxon is thoroughly described and collection sites are given. Almost all the northern desert species and their hybrids are figured with photographs, and the newly described species and members of the A. "nyttallii" group are figured with line drawings. As the fruiting bract appears to have the most useful diagnostic value, these are illustrated for all northern desert species and hybrids. An attempt has been made to put the nomenclature in order and all synonyms are given. The epithet A. "nuttallii" Wets. is invalid because it is antedated by A. gardneri (Moq.) Dietr .

The data for this problem were collected at the Desert Range Experiment Station and on adjoining public domain lands during the summer of 1934, for the purpose of studying the influence of overgrazing on the increase of palatable and unpalatable desert forage plants. A vegetative description of the two areas studied has been prepared and presented.

No description available.

No description available.

No description available.

Disseminated precious-metal mineralization occurs at the Morning Star deposit, in the upper-plate of the Morning Star thrust which represents intermediate age (105 and 90 Ma) faulting along the Mesozoic foreland fold and thrust belt (MFFTB). Deformation along the Morning Star thrust consists of both ductile and brittle events, and is different than deformation on other structures in the MFFTB in the northeastern Mojave Desert. The different style and episodic nature of deformation, together with the spatial relationship to the Teutonia batholith, accounts for mineralization on the Morning Star thrust and the absence of mineralization on other thrusts in the belt. Two stages of mineralization have been identified in the Morning Star deposit. Six distinct types of electrum have been identified. Electrum occurs as free grains, fracture fillings, or as inclusions in minerals during primary mineralization, and as rims around early electrum or as intergrowths with covellite and acanthite during secondary mineralization. Textures and compositions of the electrum and Ag+Au-sulfides indicate Au and Ag remobilization was isochemical in the lower portions of the deposit, while remobilization at upper levels of the deposit resulted in gold enrichment. Hydrothermal fluids (H₂O-CO₂-6 wt.% NaCl), that were driven by Late Cretaceous igneous activity, scavenged metals from the host rocks to form the Morning Star mineralization. Early mineralization is syn-tectonic, but the bulk of the mineralization is post-tectonics. The bulk of the main stage mineralization was precipitated into open spaces at temperatures between 280° and 330°C by a combination of reduction and increased acidity of the fluid due to wall rock reactions. Ore grades have subsequently been increased by Au and Ag remobilization. / Ph. D.