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- Creators: School of Mathematical and Natural Sciences
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Description
Desert ecosystems are one of the fastest urbanizing areas on the planet. This rapid shift has the potential to alter the abundances and species richness of herbivore and plant communities. Herbivores, for example, are expected to be more abundant in urban desert remnant parks located within cities due to anthropogenic activities that concentrate food resources and reduce native predator populations. Despite this assumption, previous research conducted around Phoenix has shown that top-down herbivory led to equally reduced plant biomass. It is unclear if this insignificant difference in herbivory at rural and urban sites is due to unaltered desert herbivore populations or altered activity levels that counteract abundance differences. Vertebrate herbivore populations were surveyed at four sites inside and four sites outside of the core of Phoenix during fall 2014 and spring 2015 in order to determine whether abundances and richness differ significantly between urban and rural sites. In order to survey species composition and abundance at these sites, 100 Sherman traps and 8 larger wire traps that are designed to attract and capture small vertebrates such as mice, rats, and squirrels, were set at each site for two consecutive trap nights. Results suggest that the commonly assumed effect of urbanization on herbivore abundances does not apply to small rodent herbivore populations in a desert city, as overall small rodent abundances were statistically similar regardless of location. Though a significant difference was not found for species richness, a significant difference between small rodent genera richness at these sites was observed.
ContributorsAlvarez Guevara, Jessica Noemi (Co-author) / Ball, Becky A. (Co-author, Thesis director) / Hall, Sharon J. (Co-author) / Bateman, Heather (Committee member) / School of Sustainability (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Water is the main driver of net primary productivity (NPP) in arid ecosystems, followed by nitrogen and phosphorous. Precipitation is the primary factor in determining water availability to plants, but other factors such as surface rocks could also have an impact. Surface rocks may positively affect water availability by preventing evaporation from soil, but at higher densities, surface rocks may also have a negative impact on water availability by limiting water infiltration or light availability. However, the direct relationship between rock cover and aboveground net primary productivity (ANPP), a proxy for NPP, is not well understood. In this research we explore the relationship between rock cover, ANPP, and soil nutrient availability. We conducted a rock cover survey on long-term fertilized plots at fifteen sites in the Sonoran Desert and used 4 years of data from annual plant biomass surveys to determine the relationship between peak plant biomass and surface rock cover. We performed factorial ANCOVA to assess the relationship among annual plant biomass, surface rocks, precipitation, and fertilization treatment. Overall we found that precipitation, nutrients, and rock cover influence growth of Sonoran Desert annual plants. Rock cover had an overall negative relationship with annual plant biomass, but did not show a consistent pattern of significance over four years of study and with varying average winter precipitation.
ContributorsShaw, Julea Anne (Author) / Hall, Sharon (Thesis director) / Sala, Osvaldo (Committee member) / Cook, Elizabeth (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Pollution causes many health problems in the modern world and the desert climates struggle with pollution in unique ways. In the Sonoran Desert, the research was conducted with the purpose of expanding the knowledge of the topic in this area. A literature review was conducted based on air, soil and noise pollution in the region. The Sonoran Desert has high levels of carcinogenic elements along with other pollutants due to the main industries of mining, agriculture and manufacturing. Overall, these findings show people in desert climates deal with high levels of pollutants.
ContributorsWest, Katherine (Author) / Hackney Price, Jennifer (Thesis director) / Savalli, Udo (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor)
Created2023-05
Description
In the Spring of 2021, I had an internship with Butterfly Wonderland, where I worked in their conservatory and learned about the ecological relationship between butterflies and plants. As part of my internship, I encouraged guests to learn more about gardening for pollinators. That experience inspired me to complete a creative project in which I would design a butterfly garden of my own that would highlight wildlife benefits and be accessible to people like myself, who do not have their own gardens and don’t have hundreds of dollars to spend on gardening supplies.
In collaboration with Dr. Gwen Iacona and Liz Makings (director and second committee member respectively), I planted accessible gardens. By “accessible”, I mean that the gardens were affordable (less than $100 total), included free/upcycled materials wherever possible, and are easily replicable. For my project, I made ‘prototypes’ of the gardens by using freely available seeds and soil sources, germinating those seeds in the ASU Greenhouses, and documenting my process so that it could be shared. Freely available seeds and other materials came from a variety of places including the ASU seed library, local Free Little Libraries, donations, as well as purchases from on campus fundraisers. The germination and growth of seeds in the ASU greenhouse took place over the course of several months in the fall and winter. That documentation has taken on several forms, including an informational pamphlet about wildlife gardening and flyers specific to locally available plant seeds. I find this to be very important because my end goal was to create something that other students or people in our community can use in a practical way. I wanted to create something that will bring gardening into the homes of people who didn’t think they were able to participate in it.
ContributorsBernat, Isabella (Author) / Iacona, Gwen (Thesis director) / Makings, Elizabeth (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor)
Created2022-05
Description
Arid and semiarid ecosystems (known as drylands) cover 45% of global land area and are predicted to expand to encompass half of the world’s land area by the end of the century. Litter decomposition plays a large role in nutrient and carbon cycling in dryland ecosystems, yet it remains poorly understood. Models that accurately predict decomposition in mesic ecosystems fail to accurately describe decomposition in drylands due to differing drivers of decomposition but also because litter in drylands accumulates around litter retention elements (LREs). LREs can be any object or surface that inhibits the movement vectors (e.g., wind) that push litter across drylands, creating a “pool” of litter around the LRE. Litter pooling increases the amount of mixing between litter and soil, creating a microclimate more conducive to microbial decomposition. Due to the increase in microbial decomposition, the decomposition rate for litter around LREs can be markedly different than that of litter not in LREs. To further understand how much litter accumulates in LREs, I studied the differences in litter accumulation between LREs and open areas in five drylands across the Southwestern United States. To do this, I visually analyzed photos of 424 litterbags to determine the cover percentages of four different types of organic litter (grass, broadleaf, reproductive, woody) and rock litter. Visual analysis of litterbags consisted of manually delineating the percent coverage of each of these litter categories. Litterbags had been placed in both open intercanopy areas as well as woody sub-canopy areas in which the plant canopy acted as the LRE. Additionally, 45 of these litterbags were randomly selected for analysis in the computer program FIJI (FIJI is Just ImageJ) to assess the litter area find the percent difference between visual and digital analysis. Areas underneath woody sub-canopies accumulated far more organic matter litter over time than open areas between canopies did but displayed a similar amount of rock litterbag cover. Shrub microsites also displayed far more varied litterbag cover percentages than open microsites. Data also suggested that litter does not always accumulate underneath shrubs or open intercanopy areas and may dissipate as time progresses. These results support the idea that litter accumulation varies throughout drylands, and that soil and litter mix frequently in LREs such as under woody plant canopies. The percent difference between FIJI analysis and visual analysis was generally negative, reflecting that visual estimation of litterbag cover was typically smaller than digital estimates. Cumulatively, litter was shown to accumulate much more around LREs and even move from them – supporting the idea that litter decomposition models need to account for litter movement in drylands to be accurate.
ContributorsNelson, Benjamin (Author) / Throop, Heather (Thesis director) / Ball, Becky (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2022-05
Description
Aboveground-belowground relationships between vegetation and its associated soil biotic community play an important role in every terrestrial ecosystem for nutrient cycling and soil health maintenance. Deserts are especially sensitive to change and little is known about Sonoran Desert soil microbiota, while exotic herbaceous species are increasingly invading into the ecosystem with other harmful effects. In many other environments, soil communities have been associated with both plant species and plant functional type. The soil community food web depends on the sustenance brought by vegetation, and different soil community members are adapted to different diets. In this paper, we hypothesized that invasive plants would cause belowground soil communities to have greater abundance and lesser diversity than those under native, more locally established plants. To test this hypothesis, we selected four desert understory plant taxa: one native grass, one native forb, one invasive grass, and one invasive forb. We predicted that the invasive plants would be associated with a greater count of microarthropods per unit mass of soil but lesser microarthropod species diversity. The invasive plants were not statistically associated with a greater count of microarthropods per kilogram of soil nor lesser microarthropod species diversity. There was not a significant difference in abundance in the microarthropod categories between native and invasive plants, so the hypothesis was rejected. However, the invasive Erodium cicutarium was found to harbor high soil mite abundance, which warrants further study, and it is yet to be seen whether soil moisture and proximity to trees played a role in the data. The results of this study should help in generating more informed hypotheses regarding desert aboveground-belowground relationships.
ContributorsStern, Argon (Author) / Ball, Becky (Thesis director) / Sanin, Maria (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor)
Created2022-05
Description
The use of DNA testing has been focused primarily on biological samples such as blood or saliva found at crime scenes. These types of evidence in the forensic field are sometimes difficult to come by, especially when there is no body to find to verify things such as identity or status of a person. In the case of the burial of a body, they can be remote and relocated multiple times depending on each situation. Clandestine burials are not uncommon especially in the Arizona desert by the United States and Mexico border. Since there is no physical body to find the next best avenue to finding a clandestine burial is through search teams which can take weeks to months or other expensive technology such as ground penetrating radar (GPR). A new more interesting avenue to search for bodies is using the most found material–soil. Technology has allowed the possibility of using soil DNA microbiome testing initially to study the varieties of microbes that compose in soil. Microbiomes are unique and plentiful and essentially inescapable as humans are hosts of millions of them. The idea of a microbiome footprint at a crime scene seems out of reach considering the millions of species that can be found in various areas. Yet it is not impossible to get a list of varieties of species that could indicate there was a body in the soil as microbiomes seep through from decomposition. This study determines the viability of using soil microbial DNA as a method of locating clandestine graves by testing 6 different locations of a previous pig decomposition simulation. These two locations give two different scenarios that a body may be found either exposed to the sun in an open field or hidden under foliage such as a tree in the Sonoran Desert. The experiment will also determine more factors that could contribute to a correlation of microbiome specific groups associated with decomposition in soil such as firmicutes. The use of soil microbial DNA testing could open the doors to more interpretation of information to eventually be on par with the forensic use of biological DNA testing which could potentially supplement testimonies on assumed burial locations that occurs frequently in criminal cases of body relocation and reburial.
ContributorsMata Salinas, Jennifer (Author) / Marshall, Pamela (Thesis director) / Bolhofner , Katelyn (Committee member) / Wang, Yue (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor) / School of Humanities, Arts, and Cultural Studies (Contributor)
Created2022-05