abstract: For this study, the flora of the northern section of the Lower Verde River, within the Tonto National Forest in Yavapai and Gila Counties, Arizona was documented and analyzed. The study site, part of the northern leading edge of the Sonoran Desert, encompasses about 16,000 hectares and is located approximately 45 miles north-northeast of Phoenix. The area, extends roughly 28 river miles from the East Verde River in the north to Chalk Mountain in the south and is largely only accessible by foot, or by boat, and as a result was previously extremely under-collected. Over a three-year study period, from August, 2017 to May, 2020, 835 plant specimens were collected and identified, representing 360 species which, combined with earlier herbarium specimens collected by others, resulted in 427 plant species found in the study area. The plant diversity of this remote region reflects three distinct vegetation communities: upland Sonoran Desert, perennial riparian corridor, and semi-desert grasslands. Together, these communities act as an important transition zone between the Sonoran Desert and higher elevation habitats. Perennial streams are biodiversity hotspots within the study area. For example, the 400 hectares of Red Creek that falls within the study boundaries contain 28% of the total species. The study site contains several plants of conservation importance including 12 species endemic to Arizona, 22 vulnerable or imperiled species, five US Forest Service sensitive species, and one Federally Endangered species. In order to compare the diversity of the Lower Verde River Flora to nine other similar/related floras in Arizona, a species-area curve using five different models was generated. The resulting models showed the Lower Verde River flora to be very close to, although slightly below, the species-accumulation curve which may indicate that roughly 50-100 species may yet be added to the flora. This prediction seems realistic, as there were several locations that could not be collected due to remoteness and excessive heat. / Dissertation/Thesis / Masters Thesis Plant Biology and Conservation 2020

Desert environments are characterised by harsh conditions and possess low biodiversity largely caused by abiotic factors such as; low precipitation, soil organic matter, high temperatures, high levels of evapo-transpiration, pH and salinity. These factors significantly reduce primary production, which influences the availability of food resources for deserts organisms. The diversity and the drivers of diversity for below ground invertebrates including Collembola (springtails) are relatively unknown in the Namib Desert. Previous morphological studies have found only five species on the basis of traditional taxonomy. This study assesses the diversity of Namib Desert Collembola and determines the effect of environmental parameters on this diversity, The diversity of Namib Desert Collembola was assessed using DNA Barcoding. The sequence information of the 178 Collembola specimens, taken from mitochondrial barcoding using the Cytochrome-c oxidase subunit I (COI) gene, was analyzed and Molecular Operational Taxonomic Units (MOTUs) were defined. Collembola community responses to soil physicochemical properties were investigated by using Redundancy Analysis (RDA). MOTUs were successfully indentified to family level (Isotomidae, Neanuridae and Sminthuridae). The researcher found a total of 30 MOTUs, most of which showed limited geographical localisation. The mtDNA COI (barcode) locus revealed high levels of previously unreported genetic diversity of Collembola in the Namib Desert. The RDA indicated that none of the soil physicochemical properties significantly drove variation in Collembola community composition. However, total soil nitrogen was shown to be a strong but not significant driver of variation in community composition (p<0,054). The taxonomic identification of the Collembola specimens was also attempted using traditional morphological analysis. A total of 23 individuals, collected from pitfall traps or extracted from soil samples, were selected for identification. Available European keys were used for identification to genus level where possible. A total eight of specimens were identified to genus level (Folsomides sp), 14 to family level (Entomobryidae) and one to order level (Symphypleona). Both Symphypleona and Entomobryidae were previously unreported from the Namib Desert. The Folsomides genus and the family Entomobryidae were the most abundant groups. This research suggests that soil dwelling Collembola in the Namib Desert have a much higher level of diversity than previously known. However, the study also highlighted the need for a more comprehensive database for Namib Collembola that includes COI sequence data as well as the morphological identification of species. / Dissertation (MSc)--University of Pretoria, 2018. / National Research Foundation (NRF) / Genetics / MSc / Unrestricted

My thesis entails an examination into the presence of the sublime in two novels by Cormac McCarthy: his postmodern western The Crossing and his apocalyptic work The Road. I draw on Kant's aesthetic theory of the sublime, specifically focusing on the Dynamical and Mathematical sublime in relation to the settings of these two narratives. For the sake of brevity, I limit my study to nature's and religion's relation to the sublime in these works. Areas of particular interest to me include: a) How/why the characters of each novel appear unaffected by or even resigned to the lack of control or explanation concerning their surroundings and b) Whether the characters' sense of choice is dependent upon the presence of the sublime in their surroundings. At the thesis' conclusion, I suggest further routes for research, such as the potential connection between the aforementioned Kantian notion of human freedom and a burgeoning concept of morality in McCarthy's later novels, and perhaps a link from McCarthy's sublime and otherworldly slant to literary subgenres such as Magical Realism.

We introduce the notion of nested distance desert automata as a joint generalization and further development of distance automata and desert automata. We show that limitedness of nested distance desert automata is PSPACE-complete. As an application, we show that it is decidable in 22O(n2) space whether the language accepted by an n-state non-deterministic automaton is of a star height less than a given integer h (concerning rational expressions with union, concatenation and iteration). We also show some decidability results for some substitution problems for recognizable languages.

A theoretical investigation of the factors that affect the population dynamics of annual plants growing in deserts was conducted through the use of computer modeling techniques. A series of three models of the yearly life cycle of desert annuals was constructed and their behavior examined. The dissertation centers around the third and most complex model, a computer simulation model with distinguishable seed cohorts in a randomly varying rainfall environment. A typical simulation run was for 80 years and cost $1.00. The five plant functions were (l} seed losses (mainly predation) as a function of seed age, (2) seed dormancy as a function of seed ages (3) percent germination of the non-dormant seeds in response to germinating rainfall, (4) percent survival from the seedling stage to maturity as a function of total rainfall over the growing season and seedling density, and (5) seeds produced per p 1 ant as a function of total rainfall over the growing season and density of mature plants. The stochasitc rainfall generator used historical rainfall probabilities from US Weather Bureau stations at Las Vegas, Nevada and Tucson, Arizona. The literature on desert annuals was carefully searched to provide supporting data for the plant functions used in the simulation model. Most of the data is for winter annuals growing on the Nevada Test Site near Las Vegas. Single species data are rare, so the model functions reflected the average plant responses for winter annuals as a group. This base run set of functions reproduced the observed data quite well. Sensitivity analysis of the simulation model indicated that in order to persist in the Las Vegas area, the seeds of annuals should have at least a one-year period of dormancy and a minimum threshold of about 15 mm of germinating rainfall. The age distribution of the seed reserves in the soil and the percent germinable is strongly influenced by the recent rainfall history of the site and the seed loss rate. The optimum balance is when the losses of older seeds from the seed reserves due to germination is the same size as the sum of the non-productive losses (e.g., predation). Several experiments are suggested -- some to cover gaps in the published data and some that became evident through the sensitivity analysis of the model itself.

I conducted field studies during 1984-1988 to determine how (1) precipitation amount and distribution affect buffelgrass [Cenchrus ciliaris L. (Link) l productivity, (2) summer rainfall amount and distribution and temperature influenced the spittlebug (Aeneolamia albofasciata Lalleman) life cycle, and (3) summer burning affects spittlebug densities and buffelgrass productivity. Experiment I was conducted from 1985 through 1988. Forage samples collected at 15 -day intervals were separated into live, recent-dead standing, old-dead standing, and litter. There was a positive relationship between the summer precipitation and the live biomass. Recent-dead standing and old-dead standing decomposed during the summer, fall, or spring. Experiment II was conducted during summers of 1984, 1985, and 1986. studied climatic effects on spittlebug life cycle and monitored nymph and adult populations. Egg hatch occurred after accumulative summer precipitation exceeded 50 mm. Five nymphal stages were completed in an average of 27 days and the life cycle averaged 43 days. Experiment III was conducted during the summer of 1985 and 1986. Four burning treatments were applied at different stages within the spittlebug life cycle. Burning should be conducted as buffelgrass initiates summer growth, and between the second and third nymphal stages. Burns conducted before plant growth and during rapid growth damaged the plant , and insect control was inconsistent. My studies will help ranchers in northwestern Mexico, south Texas, and northeast Mexico effectively manage buffelgrass pastures. Forage accumulation and decomposition cycles can be used to adjust stocking rates, and knowledge of the insect life cycle and plant productivity can be used to maximize insect control and minimize adverse effect on plant productivity.

The ecology of bighorn sheep in Canyonlands National Park, Utah was investigated between July 1974 and December 1975. Primary objectives of this study were: (1) to determine the distribution and abundance of bighorn sheep in the Park; (2) to examine the effects of human encroachment, and (3) to determine key habitat factors in relation to bighorn sheep movements. Data were collected by ground and aerial surveys. There were between 60 and 100 bighorn sheep in the Island in the Sky District and between 20 and 30 in the Needles District. Bighorn sheep distribution was closely related to the history of livestock grazing and landform characteristics of the canyons. Human activities have restricted bighorn ewe distribution more than ram distribution. Bighorn ewes were observed in canyons which were not used by domestic livestock or where much of the canyon was isolated from domestic livestock. Deer and bighorn sheep demonstrated different landform preferences. Deer occupied large level areas, washes, and river bottoms. Bighorn sheep remained on the more rugged terrain, moving to level areas to feed. In canyons which were completely isolated from deer and livestock, bighorn sheep preferred t he broad level areas and washes. Bighorn ewes did not demonstrate seasonal movements, whereas rams had definite movement patterns. In the southern portion of the Island in the Sky District , rams formed small bands and remained in a series of four canyons throughout the late winter and spring . In June, these rams dispersed individually or in pairs to higher elevations. During October they returned to the canyons below the White Rim to search for ewes. In the eastern portion of the Island in the Sky District, mature rams remained below the White Rim only during the rut, dispersing to higher elevations for the rest of the year. Physical barriers may minimize the impact of tourism upon bighorn sheep. If bighorn sheep were above or unable to see the source of disturbance , the impact was not as great as when bighorn were able to see the source. This may explain the tendency for bighorn ewes to quickly retreat when vehicles approached them on the White Rim Road where few physical barriers are present. Human encroachment also decreases the energy intake and increases the energy output of bighorn sheep. Bighorn sheep appear to be at equilibrium with the current range they inhabit. The National Park Service should monitor the use of the White Rim Road to evaluate effects on the bighorn sheep and restrict hiking below the White Rim to minimize stress on the bighorn sheep within this range. Studies should be initiated to investigate the bighorn sheep expansion of its range within the Park as a result of the cessation of lives tock grazing, and the role tourism plays in limiting it.

The heat exchange during dry conditions in Curlew Valley for selected clear days is determined from recordings in 10 minute intervals . The two heat budget components , radiative exchange and heat flow in the soil, are studied in detail. Maximum surface temperature due to radiative exchange above, assuming no heat loss by other components, is determined. Reduction of surface temperature by heat conduction into the ground was calculated as a second step to solve the heat budget equation. Substantial heat flow throughout a day is restricted to the upper 10 em of the soil. Diffusivity of the soil was determined from soil temperature using phase and amplitude equations, of which the first gave better results.

This research contributes to the field of land use planning by examining the effects of demographic trends--also known as demographic futures--on growth and development projections for seven communities in the Mojave Desert region of San Bernardino County, California. Demographic trends based on California Department of Finance projections and land development data supplied by the Southern California Association of Governments were obtained for each of the communities for the period between 1990 and 2001. By using a spatially explicit urban growth model, these trends and data were then used to allocate community-specific future growth for Adelanto, Apple Valley, Barstow, Hesperia, Twentynine Palms, Victorville, and Yucca Valley. The research compared three projected settlement densities for each community. These three densities were based on settlement trends between 1990 and 2001, on existing densities as of 2001, and on densities that had been derived from prior research in the Mojave Desert region as a whole. The overall effect of using demographic trends to estimate settlement densities results in less development of open space and undeveloped lands than under existing densities or densities derived from prior research. Indeed, using demographic trend-derived densities in place of existing densities resulted in nearly 3,900 more acres of vacant land in the seven communities remaining undeveloped by the year 2020. Similarly, using demographic trend-derived densities in place of densities developed by prior research resulted in nearly 22,000 more acres of vacant land in the seven communities remaining undeveloped by the year 2020. Differences in projected land use patterns based on demographic trends are a key point for land use planners to consider when determining future development in each of the communities. Accounting for these demographic trends provides a way of "fine tuning" projections to ensure that they are more representative of the needs and expectations of future populations.

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