Physical Sciences and Mathematics Commons^™

Quantifying The Effect Of Disturbance On Native Mojave Desert Shrubs, Tamara J. Wynne

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disturbance can come in many different forms. In our studies, we looked at the impact of a solar photovoltaic facility on native plants growing inside and outside of the facility, alteration in precipitation (simulated) on four native shrubs and the impact of applying supplemental water as a function of volume and frequency to establish native shrubs such as might occur at restoration sites. Disturbance is becoming a more common phenomenon in many ecosystems throughout the world, increasing the need for studies that quantify the impact at the plant and ecosystem level. Each research project revealed different plant responses, such as …

Estimation Of Spatial Change In Cropland Area And Evaluation Of Irrigation Performance In Imperial Valley Using Remotely Sensed Data, Usha Poudel

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Imperial Valley (IV) in the US is an extensively irrigated agricultural region, which includes multiple crops changing on an annual and semiannual basis. The valley is facing grave concerns about water management due to its semi-arid environment, water intensive crops, and limited water supply. A simple, inexpensive, and repeatable method to detect changes in cropping patterns may assist irrigation managers to understand crop diversification and associated consumptive use. In addition, a spatial assessment of existing water irrigation system performance and productivity is crucial to benchmark and improve current water management strategies. This thesis estimates the spatial pattern of change …

Light Conditions During Desiccation And Rehydration Impact The Recovery Of Cultured Timmiella Crassinervis, Sotodeh Ebrahimi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many terrestrial mosses of xeric environments experience excess light during extended periods of desiccation. While dry or hydrated, excess light energy can lead to formation of reactive oxygen species and photoinhibition (e.g. damage to Photosystem II) which affects photosynthetic stress and efficiency. This study aimed to determine the effect of duration dry and light intensity (PAR) on cultured shoots of the chaparral moss Timmiella crassinervis, as well as to elucidate the optimal rehydration light conditions for this species. I hypothesized that 1) mosses exposed to higher light intensities during desiccation would incur more damage upon rehydration than those exposed to …

Can Desert Mosses Hide From Climate Change? The Ecophysiological Importance Of Habitat Buffering & Water Relations To A Keystone Biocrust Moss In The Mojave Desert, Theresa Ann Clark

UNLV Theses, Dissertations, Professional Papers, and Capstones

Empirical and observational studies suggest a keystone biocrust moss, Syntrichia caninervis, may be sensitive to future climate change in the American Southwest due to its uniquely sensitive water relations that appear particularly challenged during summer hydration-desiccation cycles. However, the potential mitigating roles of habitat buffering, acclimatization, and winter recovery on the vulnerability of this species remain largely unexplored. I investigated potential abiotic and biotic resiliency factors driving summer stress resistance and recovery in S. caninervis along present-day aridity gradients in the Mojave Desert to strengthen the climate change vulnerability assessment for this species common to biocrusts of North America, northern …

Synthesis And Characterization Of Synthetic Urban Melt Glass, Rebecca Kristien Lowe

UNLV Theses, Dissertations, Professional Papers, and Capstones

Melt glass formed from the explosion of a nuclear device is a unique post-detonation material that can aid in the ensuing forensics investigation. Trapped in the melt glass are chemical and isotopic signatures that can provide diagnostic and source information about the weapon by comparison with documentation of previous detonations. A nuclear terrorist attack would likely take place in an urban environment and as such, the melt glass formed would consist of a complex matrix including urban materials like cement and glass, activation products from the large neutron flux that will be seen, and fission products from the detonation. The …

Landscape Scale: Inter- And Intraspecific Variation In Plant Interactions Along A Stress Gradient In The Sheep Range Of Nevada, Jordan Dowell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Impending threats to shrubland ecosystems, posed by climate change, necessitate niche modeling efforts to project vegetation range shifts. However, efforts often remain unguided by individual-scale interspecific plant interactions. The stress gradient hypothesis posits that facilitation should increase in areas of high abiotic stress, only if the individuals are able to ameliorate the surrounding area via functional traits. The Sheep Range of Nevada was used to assess the role of functional traits as predictors of plant association. Larrea tridentata, Coleogyne ramosissima, and Artemisia nova were selected as shrubs with variable life history strategies and ranges in order to identify general patterns …

Effects Of Rate Of Drying, Life History Phase, And Ecotype On The Ability Of The Moss Bryum Argenteum To Survive Desiccation Events And The Influence On Conservation And Selection Of Material For Restoration, Joshua Lee Greenwood, Lloyd R. Stark, Lindsay P. Chiquoine

Life Sciences Faculty Research

Desiccation stress is frequently experienced by the moss Bryum argenteum and can influence survival, propagation and niche selection. We attempted to disentangle the interacting factors of life history phase (five categories) and rate of desiccation (time allotted for induction of desiccation tolerance) for 13 ecotypes of B. argenteum. Using chlorophyll fluorescence as a stress index, we determined how these parameters influenced desiccation tolerance. Rate of drying and life phase significantly affected desiccation tolerance. The reaction norms of desiccation tolerance displayed by the 13 ecotypes showed a substantial degree of variation in phenotypic plasticity. We observed differences in survival and fluorescence …

Application Of Semi-Hydrophobic Layers To Decrease Bare Soil Evaporation, Jesse Lee Barnes

UNLV Theses, Dissertations, Professional Papers, and Capstones

Evaporative water loss from bare agricultural soils is a primary area of water conservation research. Mulching is the commonly utilized method to decrease evaporative water loss. The most commonly utilized mulch is nonbiodegradable polyethylene sheeting because it tends to decrease evaporative water loss and increase crop yields more than environmentally friendly mulches. This study aimed to test the utility of sand coated with polymerized soybean oil (i.e., hydrophobic sand) as a treatment to reduce bare soil evaporation and an alternative to current practices. Evaporation rates were measured in laboratory soil columns containing both treated and untreated soils. Treatment parameters were …

Assessing The Importance Of Nurse Plant Associations To The Growth Of Pre-~Reproductive Yucca Brevifolia, Eric James Chameroy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facilitation and competition among plant species, in addition to abiotic factors, play an important role in determining plant community structure in arid and semi-arid environments. I conducted a study in Dry Lake Valley, Lincoln County, Nevada, USA to investigate the importance of nurse plant associations to pre-reproductive Yucca brevifolia (Joshua tree). Dry Lake Valley lies within a transition desert between the Mojave and Great Basin Deserts with ecotonal plant communities consisting of species representative of both deserts. A vegetation survey described the communities in which this study was conducted as a Y. brevifolia woodland dominated by an understory of Ephedra …

Assessing Growth Response To Climate Controls In A Great Basin Artemisia Tridentata Plant Community, Lorenzo F. Apodaca

UNLV Theses, Dissertations, Professional Papers, and Capstones

An assessment of the growth response of key vegetative species to climatic variability is vital to identifying possible local impacts on ecosystems faced with imminent climate change. With current climate projections in Nevada predicting a shift to an even more arid climate with greater year-to-year variability, the imperative exists to identify the effects of specific climatic controls on plant growth and to research methods to assess large-scale vegetative changes, especially in more remote areas where readily available data sets may be lacking. This study utilized annual growth ring indices constructed from big sagebrush (Artemisia tridentatassp.tridentata) stems collected in Spring Valley, …

Exploring The Seed Bank Dynamics Of Red Brome: Longevity, Density, And Relationship To Fire, Benjamin S. Jurand

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores several untested aspects of the seed bank characteristics of red brome (Bromus rubens), an invasive annual grass in southwestern United States arid lands. Red brome is a formidable competitor to native plant species, both annual and perennial alike, and produces many seeds that germinate easily. The stalks of red brome contribute continuous-cover fuel loads that facilitate wildfires destructive to mature native Mojave Desert plant communities. This makes it a priority species for land managers, particularly when dealing with recovery after fire.

This project addressed questions related to the longevity of red brome seeds in soil seed banks …

Investigating Three Decades Of Vegetation Change In A Mojave Desert Mountain Range, Chris Lee Roberts

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project is a vegetation change study spanning 29 years in the Newberry Mountains of Southern Nevada. Long term monitoring data are crucial for understanding the effects of climate change on vegetation dynamics. Successful management intervention in vegetation change will require identification of early indicator plant species and their responses to climatic cues. This project is one of the oldest comparisons of resurveyed Mojave vegetation community plots with repeatable methodology and the longest survey interval reported for the southeastern Mojave Desert. 103 plots were relocated and resurveyed based on data methods in Jim Holland's thesis titled "A Vegetative Analysis of …

Natural And Constructed Wetlands For Ecosystem And Engineering Services In The Arid And Semi-Arid Regions, Achyut Raj Adhikari

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Wash (LVW) has undergone significant wetlands degradation and soil erosion over the past thirty years due to increasing flow resulting from urbanization and large rainfall events in the Las Vegas Valley Watershed. The increased flow and associated pollution load in the LVW and its adverse impact in Lake Mead have alerted stakeholders to pay a greater attention to explore alternative measures for rehabilitation of wetland ecosystems. This dissertation, using the case of changes in LVW, analyzes and describes ecological and engineering services provided by wetlands in arid and semi-arid regions and provides a knowledge base that can …

Bryoecology In The American Southwest: Patterns Of Biodiversity And Responses To Global Change, John Carroll Brinda

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation combines investigation of the large-scale responses of bryophyte species diversity and distribution with small-scale physiological adaptations to global change. These two areas of inquiry are linked because one way to predict plant species responses to global change is to examine their distribution across current ecological gradients produced by factors such as latitude and elevation. By examining these biogeographic patterns one can identify those species that have a narrow tolerance and therefore are most sensitive to change. Selected bryophytes might then be used as indicator species in long-term monitoring programs. Where historical data exist, these can be used to …

Mojave Applied Ecology Notes Fall 2011, E. Cayenne Engel, Scott R. Abella, Kathryn A. Prengaman, Jason Whited, Peter Michel

Mojave Applied Ecology Notes

Paper on impacts of Mojave wildfires through time published, possibilities of catastrophic Mt. Charleston forest fires, vegetation mapping at three national parks, UNLV library’s special collections, and the benefits of scientific publications to managers and stakeholders

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …

Climate And Vegetation Change In The Newberry Mountains, Southern Clark County, Nevada, Ross Joseph Guida

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ecological studies have shown worldwide that vegetation is being affected by climate change. Species are shifting to new elevations and physiographic positions to adapt to changes in their environment. More specifically, paleoecology studies in the Mojave Desert have shown shifting vegetation patterns in response to past warming and precipitation changes. Recent studies have shown mortality among desert plants related to extended drought and warming. However, few studies have shown how the geographic distribution of Mojave Desert species has changed during this most recent period of warming. This study addresses this gap in the literature by focusing on several plant species …

Mojave Applied Ecology Notes Summer 2011, Scott R. Abella, Charles W. Denton, David G. Brewer, Rory W. Steinke, Wayne A. Robbie, W. Wallace Covington, E. Cayenne Engel, Ross Guida

Mojave Applied Ecology Notes

Thoughts on fire possibilities on Mount Charleston, estimating historical densities of Ponderosa pine in northern AZ, over-understory changes in the Spring Mountains, seeding effectiveness in Red Rock Canyon, workshop announcements.

Relationships Of Exotic Plant Invasions With Biological Soil Crust, Desert Pavement, And Soil Carbon In The Eastern Mojave Desert, Adria Decorte

UNLV Theses, Dissertations, Professional Papers, and Capstones

In a matter of 50 years, exotic annual plants have become widespread in the Mojave Desert, contributing to drastic landscape changes such as those caused by recent fires. Invasions by exotics threaten native Mojave Desert plant communities by altering community functions (e.g. fire regimes) and by reducing plant diversity. Because it is not practical, or even possible, to eradicate these exotics, developing effective prevention techniques is the key to controlling these invasions.

This thesis used a greenhouse experiment, a field experiment, and a correlational field study to examine the affect soil surface types have on the establishment of three exotic …

Exploring The Potential Of Agave As A Biofuel Crop On Arid Land, Rhea Conlu, Diana Ha, Jeffery Shen

Festival of Communities: UG Symposium (Posters)

Worldwide awareness of global warming and depleting fossil fuel sources has made research into alternative resources, such as plant fuels imperative. Since groundwater irrigation is unsustainable, especially in desert climates, plants that are drought resistant or can utilize otherwise unusable water are more viable sources of future biofuel production. Agave nevadensis, a species belonging to the family Agavaceae are succulent plants native to Las Vegas. This experiment aims to expose A. nevadensis to both wastewater and drought conditions and observe its response. The results can help define Agave as a water-resourceful biofuel both tolerant of drought and capable of utilizing …

Mojave Applied Ecology Notes Spring 2011, Scott R. Abella, Ross Guida, S. D. Smith, Christopher L. Roberts, Haroon Stephen, William J. Smith, Zhongwei Liu, James S. Holland, Aurore Giguet

Mojave Applied Ecology Notes

Red brome distribution in the eastern Mojave Desert, A look at the UNLV xeric gardens and Marjorie Barrick museum, Summary of recent science synthesis efforts

Mojave Applied Ecology Notes Winter 2011, Scott R. Abella, Alice C. Newton, Kenneth Chittick, Pam Sinanian

Mojave Applied Ecology Notes

Lake Mead’s collaborative applied science research program; “annoying the elephant” - ruminations on active management by Alice Newton, Lake Mead NRA vegetation manager; 2012 NWRA Lake Mead symposium sneak peak; assessing forest change using dendrochronology in the Spring Mountains.

Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Final Report, Scott R. Abella

Fire Science

Species selection can make the difference between successful revegetation projects and costly failures. Candidate native species for revegetating burned arid lands in the southwestern United States must meet at least two criteria. These species must: (1) be competitive in postfire environments typically dominated by exotic grasses, and (2) be able to become established reliably by seeding or planting. In response to Manager’s Request Task 3 (reestablishment of native vegetation after fires on arid lands) in the 2006 JFS announcement for proposals, this research tackled the problem of selecting native species with the greatest chance of revegetation success by conducting synergistic …

Mojave Applied Ecology Notes Fall 2010, Adria Decorte, Sharon Altman, Alex Suazo

Mojave Applied Ecology Notes

Adria DeCorte defense, Mojave desert inventory and monitoring mapping project, effect of burial depth on Brassica tournefortii seeds

Temporal And Spatial Assessment Of Evaporation, Transpiration, And Soil Moisture Redistribution, Brian M. Bird

UNLV Theses, Dissertations, Professional Papers, and Capstones

At a native stand of creosote bush (Larrea tridentata) in North Las Vegas, a rainfall simulation study was conducted over a 12 month period from October 2005 to October 2006. Simulated rainfall occurred during the winter, spring, summer, and fall periods. Rainfall simulation systems were positioned on each of 12 plots, each containing a single creosote bush. Simulated rainfall events occurred at night with multiple short pulses designed to maximize infiltration while minimizing ponding. Yearly simulated rainfall amounts were set at 0, 15, 30 and 60 cm (replicated three times) and were approximately 0, 1.5, 3.0 and 6.0 times the …

Mojave Applied Ecology Notes Summer 2010, Scott R. Abella, E. Cayenne Engel

Mojave Applied Ecology Notes

Survey of monitoring and management for conservation of rare plants, Roadside restoration techniques in Joshua Tree NP, and an update on renewable energy developments in the Southwestern deserts

Joint Fire Science Program – Lake Mead National Recreation Area Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Quarterly Progress Report, Time Period: May 1 — June 30, 2010, Margaret N. Rees

Fire Science

• Article entitled “Competitive Hierarchy of Native Desert Plants with Red Brome (Bromus rubens): Towards Identifying Invasion-Reducing Species" was submitted to the Invasive Plant Science and Management journal.
• Maintained nursery plots and added installment of nitrogen treatment.
• Took measurements in nursery (competition) plots and harvested biomass.

Joint Fire Science Program – Lake Mead National Recreation Area Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Quarterly Progress Report, Time Period: January 1 — April 30, 2010, Margaret N. Rees

Fire Science

• Article entitled “Competitive Hierarchy of Native Desert Plants with Red Brome (Bromus rubens): Towards Identifying Invasion-Reducing Species" was submitted to the Invasive Plant Science and Management journal
• Maintained nursery plots and added installment of nitrogen treatment.
• Took measurements in nursery (competition) plots and harvested biomass.

Assessing Invasive Plant Species As Threats In Mojave Desert Parks, Sara L. Mcpherson, Donovan J. Craig, Scott R. Abella

Graduate Research Symposium (GCUA) (2010 - 2017)

The invasion and persistence of exotic plant species threatens the natural features that national parks are designed to protect. For example, park managers have witnessed an increase in the frequency, extent and intensity of fires along with a reduction in native species richness and diversity. Many park managers are familiar with a suite of highly invasive plants, but lack a comprehensive and systematic way of prioritizing invasive plant species based on potential threats to the parks’ resources. We have entered into a collaborative project with the National Park Service’s Inventory and Monitoring program to develop an invasive plant early detection …

29 Years Of Vegetation Community Change Across Environmental Gradients In A Mojave Desert Mountain Range, Christopher L. Roberts, James S. Holland, Scott R. Abella

Graduate Research Symposium (GCUA) (2010 - 2017)

There is a great deal of uncertainty as to how biological communities respond to changes in land use and climate change, a situation particularly relevant in protected areas such as national parks that were designated to conserve specific biological features. Utilizing extant vegetation data sets with repeatable methodology can provide opportunities for insight into previous vegetation change and provide base line data for long-term monitoring projects useful for modeling vegetation community trajectories. We have relocated and resurveyed 106 sites from a vegetation community study initiated in 1979 in the Newberry Mountains, southern Nevada, within Lake Mead National Recreation Area managed …