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Articles 1 - 18 of 18
Full-Text Articles in Life Sciences
Ecology, Phylogenetics, And Conservation Of Draba Asterophora Complex: A Rare, Alpine, Endemic From Lake Tahoe, Usa, Emily Ruth Smith Putnam
Ecology, Phylogenetics, And Conservation Of Draba Asterophora Complex: A Rare, Alpine, Endemic From Lake Tahoe, Usa, Emily Ruth Smith Putnam
Theses and Dissertations
Rare, alpine, endemic species are particularly at risk for extinction. Alpine environments are especially vulnerable to climate change and human impacts, such as ski resort development and snowmaking. Draba asterophora Payson is a rare, alpine species that occurs only in three disjunct mountain-top regions surrounding Lake Tahoe. It is currently threatened by human impacts, such as ski resorts, as well as indirect influences of climate change and therefore in need of better understanding for conservation purposes. Draba asterophora may be able to serve as a case study for other similarly vulnerable, rare, alpine, endemic species with conservation needs. We utilized …
Post-Fire Interactions Between Soil Water Repellency, Islands Of Fertility, And Bromus Tectorum Invasibility, Kaitlynn Jane Fernelius
Post-Fire Interactions Between Soil Water Repellency, Islands Of Fertility, And Bromus Tectorum Invasibility, Kaitlynn Jane Fernelius
Theses and Dissertations
An intrinsic link exists between soil moisture and soil nitrogen. Factors that increase or decrease soil moisture can have a profound effect on soil nitrogen cycling, which may have later repercussions in the plant community. Post-fire soil water repellency is one factor that can limit soil moisture acquisition and may indirectly affect nitrogen cycling and weed invasion in woody islands of fertility. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with a surfactant to ameliorate water repellency. Two years later, soils were excavated from the untreated and treated field plots. In the greenhouse, half of …
Certain Agave Species Exhibit The Capability To Be Moderately Productive Under Conditions Of High Salt And Drought Stress, Steven J. Bergsten
Certain Agave Species Exhibit The Capability To Be Moderately Productive Under Conditions Of High Salt And Drought Stress, Steven J. Bergsten
Theses and Dissertations
Water availability and arable lands are increasingly limiting resources in many parts of the U.S., particularly in semi-arid and arid regions. As a means of addressing food and fuel demands associated with burgeoning population growth, highly productive and water-use efficient crops need to be identified. One potential crop, Agave, merits consideration and evaluation due to its putative capability to provide sustenance and energy despite growing in water-limited regions and on marginal soils. However, little is known regarding the productivity these succulent plants will have under growing conditions of the Southwest, where high concentrated saline soils are abundant, and water is …
Understory Vegetation Response To Mechanical Mastication Of Piñon And Juniper Woodlands, Jordan Ann Bybee
Understory Vegetation Response To Mechanical Mastication Of Piñon And Juniper Woodlands, Jordan Ann Bybee
Theses and Dissertations
Piñon and juniper encroachment and infilling can alter ecosystem processes and decrease resilience and resistance in sagebrush grasslands. Land managers employ a variety of techniques to eliminate these trees and mitigate their negative effects. Mechanical mastication or shredding is an increasingly popular method of removing these trees in Utah. It is a versatile treatment that can reduce canopy fuels, increase infiltration, and reduced sediment loss. We compared vegetation cover for annual and perennial vegetation functional groups on shredded and adjacent unshredded areas across a range of sites. Our approach was to categorize sites by ecological site type (encroachment or tree) …
Population Genetic Structure Of Bromus Tectorum In The American Desert Southwest, Desiree Rochelle Eldon
Population Genetic Structure Of Bromus Tectorum In The American Desert Southwest, Desiree Rochelle Eldon
Theses and Dissertations
Following its introduction to North America in the late nineteenth century, Bromus tectorum L., an inbreeding invasive winter annual grass, has become dominant on millions of hectares of sagebrush steppe habitat throughout Intermountain Western North America. It appears that within the last 30-40 years, B. tectorum has expanded its range southward into the Mojave Desert and also into more climatically extreme salt desert environments. Previous research using microsatellite markers and experimental studies has suggested that lineages found in desert habitats are genetically distinct from those found in the sagebrush-steppe habitat and possess suites of traits that pre-adapt them to these …
Importance Of Placement Depth In Evaluating Soil Nitrogen, Phosphorus, And Sulfur Using Ion Exchange Resin Capsules In Semi-Arid, Low Fertility Soils, Rachel Lynn Buck
Importance Of Placement Depth In Evaluating Soil Nitrogen, Phosphorus, And Sulfur Using Ion Exchange Resin Capsules In Semi-Arid, Low Fertility Soils, Rachel Lynn Buck
Theses and Dissertations
Ion exchange resin capsules provide a possible alternative to conventional soil testing procedures. Previous studies with semi-arid, low fertility soils observed poor relationships with poorly mobile nutrients such as phosphorus (P). We propose that placement depth may improve those relationships. Our objective was to (1) determine if placement depth could improve resin capsule estimation of the bioavailability of nitrogen (N), P, and sulfur (S) and (2) to determine if resin capsules can effectively estimate S availability in semi-arid, low fertility soils. Field sites were established in Rush and Skull Valleys, Utah on loam and sandy loam soils, respectively. Fertilizer was …
Habitat Selection By Two K-Selected Species: An Application To Bison And Sage Grouse, Joshua Taft Kaze
Habitat Selection By Two K-Selected Species: An Application To Bison And Sage Grouse, Joshua Taft Kaze
Theses and Dissertations
Population growth for species with long lifespans and low reproductive rates (i.e., K-selected species) is influenced primarily by both survival of adult females and survival of young. Because survival of adults and young is influenced by habitat quality and resource availability, it is important for managers to understand factors that influence habitat selection during the period of reproduction. My thesis contains two chapters addressing this issue for K-selected species in Utah. Chapter one evaluates habitat selection of greater sage-grouse (Centrocercusurophasianus) on Diamond Mountain during the critical nesting and brood-rearing period. Chapter two address selection of birth sites by bison (Bison …
Exploring Post-Fire Recovery Of Biocrusts And Desert Ecosystem Services, Jason R. Bahr
Exploring Post-Fire Recovery Of Biocrusts And Desert Ecosystem Services, Jason R. Bahr
Theses and Dissertations
Biocrusts and the ecosystem services they provide are becoming more susceptible to fire as exotic annual grass invasions facilitate the spread of desert wildfires. Further, precipitation patterns across the western United States are predicted to change over the next century, and have the potential to dramatically influence fire regimes and the recovery of burned biocrusts. Despite these changes to desert fire and precipitation cycles, our understanding of post-fire biocrust recovery is limited, especially regarding the first two years after fire. To investigate biocrust recovery, we created burn manipulations (i.e., unburned and burned) and tracked crust form and function over two …
Habitat Selection And Nesting Ecology Of Snowy Plover In The Great Basin, Kristen Sue Ellis
Habitat Selection And Nesting Ecology Of Snowy Plover In The Great Basin, Kristen Sue Ellis
Theses and Dissertations
Snowy plovers (Charadrius nivosus) are small, ground-nesting shorebirds that are a species of conservation concern throughout North America. Despite increased efforts to understand factors contributing to the decline of snowy plover, little is known about habitat selection and breeding ecology of snowy plover for the large population found in the Great Basin. We tested hypotheses concerning the occupancy and nesting success of snowy plover. First, we identified factors influencing snowy plover nest survival at Great Salt Lake, Utah. We hypothesized that snowy plover would demonstrate differences in nest survival rates across years due to differences in habitat characteristics, predator abundance, …
Factors Underlying Invasive Grass Fire Regimes In The Mojave Desert And Its Consequences On Plant And Animal Communities, Kevin J. Horn
Factors Underlying Invasive Grass Fire Regimes In The Mojave Desert And Its Consequences On Plant And Animal Communities, Kevin J. Horn
Theses and Dissertations
Climate change and exotic plant invasions are significant anthropogenic threats to desert community structure and resilience . In the Mojave Desert, the invasive grass red brome (Bromusrubens L) is increasing fire frequency and extent in response to climatic factors. The resilience of this ecosystem will be affected by how plant and animal communities respond to fire. To better understand these dynamics, we studied the environmental factors underlying changes in invasive grass fire regimes in the Mojave Desert and its structural and functional effects on plant and animal communities. Following fire, reestablishment of native vegetation can be preempted by repeated burning …
The Bromus Tectorum-Pyrenophora Semeniperda Pathosystem, Heather Finch
The Bromus Tectorum-Pyrenophora Semeniperda Pathosystem, Heather Finch
Theses and Dissertations
Variable mortality of Pyrenophora semeniperda--infected Bromus tectorum seeds has been referred to as a "race for survival", stating that seeds that germinate quickly are more likely to escape pathogen-caused mortality. Dormancy status is not the only variable determining outcomes within the Bromus-Pyrenophora pathosystem. Varying temperature and exposure to water may strongly influence germination outcomes of B. tectorum when in the presence of P. semeniperda. Low water potentials characteristic of semi-arid soils are often over-looked in the context of seed pathogens, and are ecologically relevant- especially for plant species that inhabit intermittently dry environments. To adequately characterize the Bromus tectorum-Pyrenophora semeniperda …
The Seed Ecology Of Rare And Endangered Gibbens' Beardtongue (Penstemon Gibbensii) And Blowout Penstemon (Penstemon Haydenii), Kassie Lorraine Tilini
The Seed Ecology Of Rare And Endangered Gibbens' Beardtongue (Penstemon Gibbensii) And Blowout Penstemon (Penstemon Haydenii), Kassie Lorraine Tilini
Theses and Dissertations
Penstemon gibbensii and Penstemon haydenii are two rare, perennial forbs inhabiting remote areas of the western United States. P. gibbensii is listed as a sensitive species by the Bureau of Land Management (BLM) in Colorado, Utah, and Wyoming (Heidel, 2009). P. haydenii was designated as Endangered by the U.S. Fish and Wildlife Service in 1987 (Heidel, 2012). This thesis research was geared toward helping land managers in their efforts to protect and rehabilitate these species by providing understanding on different aspects of their seed ecology. My first study was a laboratory experiment performed on P. gibbensii and P. haydenii seed …
Resource Legacies And Priming Regulate Microbial Communities In Antarctica's Dry Valleys, Sabrina Deni Saurey
Resource Legacies And Priming Regulate Microbial Communities In Antarctica's Dry Valleys, Sabrina Deni Saurey
Theses and Dissertations
Multiple mechanisms control bacterial community structure but two in particular, the "legacy" of past environmental conditions, and the "priming" of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. …
Geochemical Evidence Of Ancient Maya Marketplace Activities In The Puuc Hills Of Mexico And At Caracol, Belize, Jacob M. Horlacher
Geochemical Evidence Of Ancient Maya Marketplace Activities In The Puuc Hills Of Mexico And At Caracol, Belize, Jacob M. Horlacher
Theses and Dissertations
The large public plazas of the ancient Maya were likely swept clear of debris and durable artifacts that could have provided evidence of the ancient anthropogenic activities. However, geochemical residues of food or mineral ores and pigments became affixed to soil and floor particles. These particles chemically bound so that natural movement of water is insufficient to cause them to move, leaving invisible geochemical signatures of ancient activities. This line of study is focused on the relationship between the geospatial distribution of element concentrations and ancient human activities using current laboratory techniques and isopleths, or chemical concentration contour maps, to …
Habitat Selection And Response To Disturbance By Pygmy Rabbits In Utah, Robert John Edgel
Habitat Selection And Response To Disturbance By Pygmy Rabbits In Utah, Robert John Edgel
Theses and Dissertations
The pygmy rabbit (Brachylagus idahoensis) is a sagebrush (Artemisia sp.) obligate that depends on sagebrush habitats for food and cover throughout its life cycle. Invasive species, frequent fires, overgrazing, conversion of land to agriculture, energy development, and many other factors have contributed to recent declines in both quantity and quality of sagebrush-steppe habitats required by pygmy rabbits. Because of the many threats to these habitats and the believed decline of pygmy rabbit populations, there is a need to further understand habitat requirements for this species and how they respond to disturbance. This study evaluated habitat selection by pygmy rabbits in …
Microbial Responses To Coarse Woody Debris In Juniperus And Pinus Woodlands, Deborah Monique Rigby
Microbial Responses To Coarse Woody Debris In Juniperus And Pinus Woodlands, Deborah Monique Rigby
Theses and Dissertations
The ecological significance of coarse woody debris (CWD) is usually highlighted in forests where CWD constitutes much of an ecosystem's carbon (C) source and stores. However, a unique addition of CWD is occurring in semi-deserts for which there is no ecological analog. To stem catastrophic wildfires and create firebreaks, whole Juniperus osteosperma (Torr.) and Pinus edulis (Engelm.) trees are being mechanically shredded into CWD fragments and deposited on soils previously exposed to decades of tree-induced changes that encourage "tree islands of fertility." To investigate consequences of CWD on C and nitrogen (N) cycling, we evaluated microbial metabolic activity and N …
The Influence Of Anthropogenic Development Of Water On Coyotes And Kit Foxes In The Great Basin And Mojave Deserts, Lucas Keith Hall
The Influence Of Anthropogenic Development Of Water On Coyotes And Kit Foxes In The Great Basin And Mojave Deserts, Lucas Keith Hall
Theses and Dissertations
Anthropogenic provisioning of water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence distribution, competition dynamics, and behavior of native species. To elucidate the potential influences of water developments on native species, we tested hypotheses concerning the occurrence and behavior of native kit foxes (Vulpes macrotis). First, we tested the indirect effect of water hypothesis (IEWH) which proposes that water developments negatively affect the arid-adapted kit fox by enabling a …
Application Of Genome Reduction, Next Generation Sequencing, And Kaspar Genotyping In Development, Characterization, And Linkage Mapping Of Single Nucleotide Polymorphisms In The Grain Amaranths And Quinoa, Scott Matthew Smith
Theses and Dissertations
The grain amaranths (Amaranthus sp.) and quinoa (Chenopodium quinoa Willd.) are important seed crops in South America. These crops have gained international attention in recent years for their nutritional quality and tolerance to abiotic stress. We report the identification and development of functional single nucleotide polymorphism (SNP) assays for both amaranth and quinoa. SNPs were identified using a genome reduction protocol and next generation sequencing. SNP assays are based on KASPar genotyping chemistry and were detected using the Fluidigm dynamic array platform. A diversity screen consisting of 41 amaranth accessions showed that the minor allele frequency (MAF) of the amaranth …