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San Marcos
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Masters
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Biological Sciences
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- Creator:
- Grant, Timothy
- Description:
- Global nitrogen (N) deposition has increased since the beginning of the Industrial Revolution due to anthropogenic influences such as the burning of fossil fuels and application of N fertilizer. Increased industrialization is expected to continue to escalate the quantity of N released to ecosystems and the atmosphere. Soil microbial communities are susceptible to this increase in N, as microbial activity can be limited by N and these communities are known to regulate biogeochemical cycles. In this study, the response of bacterial functional groups (FG) to N addition (> 50 Kg N ha-1 yr-1) was quantified in Southern California semi-arid topsoil (0-10 cm). Soil physical-chemical properties and enzymatic activities were also quantified to further understand the direct/indirect effects of N addition on bacterial FG. Experimental N addition significantly increased the abundance N-fixing, chitinolytic, and starch degrading bacteria in semi-arid soils; while increasing N-mineralizing and denitrifying bacteria in coastal sage shrub (CSS) soil. N input also decreased the abundance metal redox bacteria in CCS soil and decreased nitrifying bacteria in chaparral soil. Furthermore, N addition increased the abundance of copiotrophic bacteria (ie: Proteobacteria, Bacteroidetes, and Firicutes) and decreased the abundance of oligotrophic bacteria (ie: Acidobacteria) in semi-arid soils. Canonical correspondence analysis revealed that the majority of FG were influenced by soil pH and extractable nitrate, which were also significantly altered by N addition. Results indicated excessive N input directly and indirectly affected the composition of the soil bacterial community. Understanding the response of the microbial community to N additions is important in predicting ecosystem functionality and stability as anthropogenic N deposition increases.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- San Marcos
- Department:
- Biological Sciences
- Creator:
- Hubbell, Marcus
- Description:
- Two species of invasive ambrosia beetles, collectively referred to as Invasive Shot Hole Borer (ISHB), began to infest Southern California’s native riparian forests in 2015. An estimated 95,791 willows had died from ISHB infestation by 2017, but the current extent and severity of ISHB infestations within San Diego County is relatively unknown. Finding infestations with ground-based monitoring is time consuming and incomplete, whereas use of Landsat data covers the entire County, and in principle could detect and monitor outbreaks much more effectively, provided that infested riparian vegetation produces a consistent spectral signature. The goal of this analysis was to correlate individual Landsat 8 bands and greenness, wetness, brightness and NDVI indices to document ISHB infestations. I used a linear analysis to generate a supervised classifier of riparian vegetation into infestation categories and evaluated performance with accuracy assessment statistics. I generated baseline models from three sources of training data to evaluate variation in spectral data that may normally occur during non-infested years due to landscape and year effects. Baseline models allowed for selection of variables that contributed to differences due to ISHB infestation, rather than natural variation. After eliminating variables that contributed to normal, non-ISHB yearly differences, results suggest differences between non-infested and infested riparian forest were detectable within Band 3 during the Post-flight season (Kappa-Cohen 42.5%). Classifying TRV forest in a single year improved model detection, although this study shows it is still necessary to evaluate previous years landscape scale differences with baseline models to assess performance. I found strong support for detecting differences between riparian forest with high rates of damage, to forest with low rates of damage within post-flight season Brightness (Kappa-Cohen 62.6%), and pre-flight Season Band 7 (Kappa-Cohen 60.2%). Results from a San Diego County wide analysis suggested site spectral wavelengths differed considerably within both baseline and treatment models, and I was unable to isolate diagnostic spectral wavelengths associated with ISHB at the county landscape level. In summary, ISHB infested forest was detectable within unique spectral wavelengths of Landsat 8 imagery. However, baseline models were required to account for landscape and year differences that may normally occur. As a management tool this analysis may be successful in identifying heavily damaged forest, which may not be easily accessed or surveyed, but not to detect early infestations.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- San Marcos
- Department:
- Biological Sciences
- Creator:
- Gomez, Joanna
- Description:
- The majority of the Biomanufacturing Students at MiraCosta College are considered to be high-risk. More than 75% are economically disadvantaged, more than 20% are veterans and military dependents, and more that 15% first in the family to earn higher education (Figure 5). To identify best practices of a Student Success Specialist at MiraCosta College six qualitative surveys were conducted. Two surveys were conducted to learn about the student population and monitor their progress and were conducted at the beginning and end of the first year in the program. Two additional surveys were conducted during the second year, the first of which was designed to find out about employment needs and the second queried job readiness/performance. Finally, a follow up survey was conducted six months post-graduation to gauge program satisfaction and learn about wage gain and job performance of graduates. In addition to gain better understanding of the role of Student Success Specialist and how to work with students, three in person interviews were conducted with experts in the field.
- Resource Type:
- Graduate project
- Campus Tesim:
- San Marcos
- Department:
- Biological Sciences