Departmental Honors is awarded to outstanding students who have a minimum GPA of 3.6 and complete an independent, original research project.
Anthropogenic greenhouse gas emissions, some of which are produced by the widespread use of gasoline-powered lawn and garden equipment, contribute substantially to global climate change. The carbon emission and sequestration potential of urban turfgrass ecosystems, which are typically maintained using polluting gasoline-powered lawn and garden equipment, is dependent on numerous factors, including climate conditions, the degree to which the turfgrass is managed, how the turfgrass is managed, soil type, and grass type. However, the extent to which turfgrass maintenance by gasoline-powered lawn and garden equipment contributes to carbon emissions in urban areas has not been closely examined. This study uses mapping technology, secondary data sources, and random sampling processes to identify correlations existing between turfgrass area, automobile traffic, and carbon emissions in the city of Los Angeles. Given that the majority of lawn maintenance equipment is gasoline-powered, I hypothesized that areas with a high proportion of maintained turfgrass would display higher carbon emissions than do areas with comparably little turfgrass. Results indicate that carbon emissions are negatively correlated with green space presence. Furthermore, traffic frequency and carbon emissions were shown to be negatively correlated, which suggests a flaw in sampling methodology, or inaccuracies with regard to the data used. The results of this study indicate that turfgrass in urban settings is sequestering carbon at a slightly greater rate than carbon is being emitted by lawn management practices. However, only limited conclusions could be drawn concerning relationships that exist between the variables, as sampling processes were applied to broadly defined urban areas. This, in turn, reflects correlations existing between variables across generalized urban settings, rather than in particularly affluent urban areas (where it is hypothesized that turfgrass management practices are causing an increase in localized carbon emissions).
The need for decarbonization with clean, renewable energy development is necessary to avoid the 2°C warming forecasted by the 2021 IPCC. Because of a lack of overarching climate change or energy policies in the U.S., individual states are predominantly responsible for managing and regulating their energy markets and deciding how – or whether – to decarbonize. The state of Nevada is also experiencing an energy deficit, with approximately 85% of energy resources imported. Although Nevada has the greatest solar generating potential in the U.S., utility scale solar developments ranked only fifth in the nation for current solar generating capacity, while most in-state electricity is generated by natural gas fired plants. And yet, expanding solar photovoltaic electricity generation has been met with roadblocks: the primary electric utility in the state, NV Energy, has worked to restrict residential rooftop solar, and further solar development on public land has been protested by many Nevada residents seeking to protect valued desert ecosystems. The present study considers the potential to combine the benefits of rooftop solar with utility-scale arrays; specifically, it calculates the maximum potential generating capacity of PV arrays mounted on industrial and commercial buildings in the three most populous municipalities in the state of Nevada, Clark County, Washoe County, and Carson City. Using geographic information systems (GIS) and object specific image recognition, this study estimates that up to 10.76-20.78 TWh of electricity could be generated annually, depending on module efficiency representing 26.62%- 51.40% of Nevada’s 2021 electricity consumption. Findings indicate that 4.71%-9.1% of Nevada’s total energy demand could be met with state-wide PV installations on commercial and industrial buildings. This suggests that using industrial rooftops for moderately sized PV installations could offset a significant amount of imported gas-fired power while also reducing disruption of previously undisturbed land by installed utility-scale solar on public lands. Moreover, installing solar PV close to where electricity is consumed reduces energy loss during transmission and the need for additional transmission lines. Findings from this study are broadly applicable to commercial and industrial centers across the U.S. and worldwide, but future research should explore the existing policy and market barriers to implementing industrial and commercial rooftop solar on a large scale in Nevada and elsewhere.
The 2015 Lake Fire that burned over 31,359 acres in the San Bernardino National Forest is one of many examples of the increasingly severe and frequent wildfires that have plagued the Southern California region over the past decades. Forests are a main source of significant global carbon sinks and as such, currently have the uptake potential to sequester carbon from the atmosphere as a possible solution to stabilize global climate change. Recent trends, however, reveal a strong association between anomalous fire weather and extreme fire behavior due to anthropogenic climate change, which creates conditions that shift areas from sinks into carbon sources that are exacerbated within a positive feedback loop. This increase in fire-related events in addition hinders the forest’s ability to fully recover and develop mature trees that can again maximize this sequestration of carbon. The literature is clear that although the global trend is a good indicator of the status of global sinks, it does not quantify the potential of regional areas. This study focuses on sampling an affected area of the Lake Fire to quantify the area’s potential capacity to sequester carbon, the amount of biomass and carbon that was lost, and the mortality rate of the sampled area to identify if such a transition took place. Incorporating these measurements to previously collected data from 2019, this study identifies trends over a larger number of samples. This study also measures the percent of carbon lost over the entire Lake Fire using a Normalized Burn Ratio of the entire Lake Fire Area. The results reveal that most of the carbon from the fire samples had indeed been lost to the atmosphere, indicating the loss of a huge area of the sink.
As the plastic industry continues to boom, the concern for the effects of microplastics on aquatic ecosystems and human health increases. Plastics remain in the environment for long periods of time because of their high durability, even when broken into small pieces. Wastewater Treatment Plants (WWTPS) have been identified as a source of microplastics (MPs) and nano-plastics (NPs) pollution into aquatic environments. Current research on microplastics doesn’t include the probability of installing filtration systems or examines the perceptions of MPs. This research study uses expert interview data to examine the feasibility of installing microplastic filtration systems in WWTPs in Los Angeles (LA) to help prevent MPs and NPs from entering the LA river and explore the perceptions of MPs and NPs. This study involved a multi-methods approach including a review of current technology, analysis of policies and LA wastewater management documents, and expert interviews to understand what LA’s plans for addressing MPs. In addition, what technologies are WWTPs in LA exploring and why, what policies have been enacted, planned or are being developed, and what are the perceptions of MPs and NPs. Current policy has created a definition of MPs but so far doesn’t require any regulation or testing for them in wastewater. This study found that water managers and WWTPS are concerned about microplastics but due to lack of data, aren’t sure how they should be addressing the pollutant. There is technology available to filter microplastics but without public pressure and support to change policy, it is unlikely this technology will be implemented. The findings of this study can be used to help develop scholarly understanding and practical information for overcoming barriers to developing, adopting, and implementing policies that could effectively reduce microplastic pollution into aquatic ecosystems.
Anthropogenic climate change, which has led to higher global average temperatures, has intensified El Nino and Pacific Decadal Oscillation temperatures. This has created a volatile climate which will impact delicate global ecosystems. Because terrestrial precipitation is caused by sea surface temperature, tracking sea surface temperature is important to predicting changes in rainfall. Trees are keystone species, and it is important to track their overall health when the climate is being drastically altered. Studying tree rings is a method which can achieve this. Past literature suggests a correlation between sea surface temperature in the eastern pacific and tree ring growth in California. An intense variation in sea surface temperature will cause drastic changes in precipitation. Because access to appropriate amounts of water is necessary to the health of plants. This variation in sea surface temperature will lead to the endangerment of the primary producers of multiple ecosystems; this will lead to global tropic cascade. This study explored if there is a correlation between sea surface temperature, precipitation, and the growth of ponderosa pine trees in Southern California. A chronology of ponderosa tree cores was sampled from the San Bernardino Mountain Range. The incremental ring width of the cores was compared to precipitation data and El Nino and Pacific Decadal Oscillation temperature data. The tree chronology was also compared to years of an extreme anomaly in sea surface temperature. The precipitation and ENSO data was used in these instances of an extreme anomaly. After measuring thirty-two cores, a correlation (r-value) of 0.403 was found between the chronology and precipitation data. A correlation of 0.448 was found between the chronology and the PDO data. No correlation was found between the ENSO and tree chronology, however, correlating the tree chronology with SST during years of extreme SST fluctuation, displays an improved correlation of 0.494. This suggests extremes in precipitation and SST influence tree growth more than small year-to-year variations and that tree growth is influenced by long-term sea surface temperature. Because of the global health crisis, these extreme events of sea surface temperature may affect the relationship between ponderosa pine tree development, sea surface temperature, and precipitation so it is important to keep this research current and updated.
Climate change is causing warming on the planet and is creating extreme weather events, including drought. The drought in Southern California has been increasing over the years. If Southern California wants to ensure a water source for occupants, stronger water conservation efforts should take place across the board. In this study, I investigate how the City of Redlands can improve water security by comparing water conservation practices. I empirically evaluate water conservation plans from the City of Santa Monica and Irvine Ranch Water District. Evaluating the effectiveness of these exemplar water districts helps compare water conservation efforts with the City of Redlands and provides guidance for strategies that Redlands can follow. I found that the City of Redlands can improve its water conservation efforts by focusing on the neighborhood level. Focusing on neighborhoods to decrease water use is important because many residents are unaware of how to use water on their lawns. In Redlands, 75% of water use in residential homes is used outdoors to water landscapes. With my research on water conservation in Santa Monica and Irvine Ranch, I have found that Redlands can reduce neighborhood water use by implementing stricter practices such as the “budget based billing” method that Irvine Ranch Water District uses. I have created a water conservation “best practices” guidelines for residents to follow to increase water resiliency and decrease water use. I will be using this information to educate community members of Redlands as I work for the Accelerate Neighborhood Climate Action Group. This can be measured by implementing the conservation efforts and comparing city water use or even comparing water use bills in neighborhoods.
As areas in the American Southwest experience reductions in seasonal rainfall, there have been radical changes in the montane meadows of Southern California. The impacts of these changes on small mammal populations that reside in these ecosystems is unclear. This study investigates the relationship between Botta’s Pocket Gopher (Thomomys bottae) burrowing activity and soil properties in montane meadows in Southern California. Data on physical properties of soil and habitat density was collected in two meadows near Big Bear, California in the San Bernardino National Forest. The easternmost meadow, Bluff, had higher silt and clay content than the western meadow, Lodgepole. We observed a positive correlation between infiltration rate and soil moisture in Bluff, and the opposite in Lodgepole. We also saw a higher density of holes in Bluff. We discovered that there was a negative correlation between the number of holes T. bottae constructed and soil moisture in both meadows, suggesting that T. bottae may see expanded habitat opportunities as these meadows shift climatically. In our warming climate, T. bottae may be able to find refuge in hard, dry soils.
Analysis and Recommendations for Management of Endangered Plants in Pebble Plain Ecosystems
The Pebble Plains are a collection of geologic deposits of Saragossa quartzite uplifted over time, and specific to the San Bernardino Mountain range. The flat, orange, and pebbled landscape is home to rare and endemic alpine plants, including Eriogonum kennedyi and Eremogone ursina, among others. These plants are federally endangered and sensitive, and yet the Pebble Plains ecosystems are under threat from anthropogenic disturbance, including trampling from nearby walking trails, crushing from unauthorized off-highway-vehicles (OHVs), introduction of invasive weeds, climate change, and other natural threats. Management strategies to prevent this disturbance include fencing, signage, and blocking off the area using boulders or snags. How effective these measures have been in preventing disturbance is not currently known. In order to study this question, spatially recorded management and disturbance data was collected, catalogued, and compared. To collect the current management data, the Collector app was used in the field at Pebble Plain sites to qualify the types of management being used, related to fencing, barriers, signage. To determine the amount of disturbance, unauthorized OHV usage, as well as walking paths, and fence breach data were recorded. These two categories of data – disturbance and management- were combined to determine what practices result in the best protection of the plant species from disturbance and associated harm on the plant populations. After preliminary data collection and analysis, current management practices were seen to be effective, but that emphasis on practices like informational signage, preventing OHV access at in-roads, and upkeep and enhancement of fencing would most effectively protect and stabilize the plant communities at Pebble Plain habitats.
Wildfires and air pollution are chronic hazards in the Southern California Inland Empire region. Wildfire frequency is increasing in California and other drought prone regions. Thus, understanding how tree growth is affected by these environmental factors is paramount for sustained tree growth. Additionally, air pollution derived from Los Angeles accumulates in the foothills of the Inland Empire, and the influence of these substances may impact forest health over time. This study evaluates the impact of localized wildfire occurrence and air pollution (NO2) and (O3) emission rates on Ponderosa Pine tree growth and ecosystem development. This is done by analyzing the growth history of 32 tree core samples taken from Ponderosa Pine trees located in the San Bernardino National Forest and compiling the data into a chronology that compares growth with wildfire and air pollution data. Wildfire occurrences had a strong negative correlation with tree growth, which resulted in interannual growth variability. However, both air pollution rates had a positive correlation with tree growth rates. This is due to compounds in NO2 that contain fertilizing properties which neutralizes O3’s negative effects on plant tissue. Below average growth rates in this region indicate that the ecosystem is still actively recovering from past wildfire incidents. Consistent average tree growth rates are likely to become progressively strained if global climate factors that influence wildfire frequency and air quality are not addressed in the near future.