Browsing by Author "Bousselot, Jennifer, advisor"
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Item Open Access Evaluating leafy green production in a Colorado rooftop agrivoltaic system(Colorado State University. Libraries, 2024) Villa-Ignacio, Armando, author; Bousselot, Jennifer, advisor; Uchanski, Mark, committee member; Sampath, Walajabad, committee memberCombining green roofs with solar modules can protect plants and produce energy in cities. Growing crops in this system is called rooftop agrivoltaics (RAV) and can complement current urban agriculture efforts. We evaluated a group of five leafy green crops (arugula, kale, lettuce, spinach, and Swiss chard) under different solar modules over two years at two locations. Data measurements were taken for fresh and dry weight (FW, DW) stomatal conductance (SC), plant size at harvest (PSH), and microclimate data. At the Colorado State University Foothills Campus, the treatments included a polycrystalline opaque silicon module, a cadmium telluride (CdTe) frameless opaque module, and a 40% semi-transparent CdTe module. At CSU Spur, there was an opaque module and a bifacial module. Both sites included a full sun control plot. At the Foothills campus, for of the five leafy greens produced higher FW and DW under the 40% semi-transparent modules compared to other treatments and the full sun control, except spinach. Most species also produced larger PSH under the PV module treatments compared to the full sun control. Leafy greens under the module treatments resulted in lower SC, however, lettuce and Swiss chard grown under the semi-transparent module treatment produced higher SC compared to all other treatments. At CSU Spur, plant responses were also species specific with arugula, kale, and lettuce yielding higher FW and DW in full sun. Most leafy greens resulted in lower SC, except for lettuce, which had a higher SC under solar module treatments. Spinach had no difference in FW but lower DW in the opaque treatment compared to the full sun control, and lower SC under both treatments. There was a lower FW between the bifacial treatment and the full sun control in Swiss chard. This research shows that incorporating photovoltaics on rooftop gardens influences the yield and stomatal conductance of select leafy green crops. While FW and DW mostly decreased under the deep shade treatments (opaque module, frameless module, and bifacial module) SC decreased, possibly due to less solar radiation on the leafy greens, reducing water use. Understanding the growth characteristics and growing environment of high value crops like leafy greens will increase understanding of what food crops are suitable for RAV systems.Item Open Access Green roof effects on floral phenology and floral nectar resources(Colorado State University. Libraries, 2023) Ruszkowski, Kyle M., author; Bousselot, Jennifer, advisor; Hufbauer, Ruth, committee member; Krishnan, Sarada, committee memberThis study investigates the potential for green roofs to support pollinator diversity and abundance in urban ecosystems through the altered floral phenology and floral abundance of plants. I compare floral phenology and the floral abundance of green roof plants to plants grown at grade on the Front Range in Fort Collins, Colorado, and how these changes may affect pollinator biodiversity in urban ecosystems. I employed an independent block design, with one green roof and one ground-level garden, approximately 120 meters apart, with replicate plants of 4 species at each garden. I found the abundance of flowers to be variable, depending on the plant species. However, all species of plants tested bloomed earlier when grown on the green roof than when grown at grade. We found pollinator abundance and diversity to be low at both the green roof and at grade. Nectar quantity and quality are diverse across a landscape and affect the health and behavior of some pollinators. I evaluated nectar volume and nectar sugar concentration between plant replicates grown on a green roof and grown at grade. Volume was measured in situ and sugar concentration was measured both in situ using a refractometer and, in a laboratory, using UPLC-RI. We found that there was no clear difference between nectar volumes of plants grown on the green roof and at grade while nectar sugar concentrations were generally higher in green roof plants.Item Open Access Investigation of flowering phenology, pollinator and invertebrate biodiversity value on urban green roofs and an evaluation of ornamental horticulture crops for pollinator value(Colorado State University. Libraries, 2024) Guidi, Michael A., author; Bousselot, Jennifer, advisor; Hufbauer, Ruth, committee member; Krishnan, Sarada, committee memberUrban green space, green infrastructure, and horticultural installations are gaining recognition for their potential to foster biodiversity. Green roofs are challenging growing environments for plants, characterized by extreme substrate temperatures, high light intensity, limited moisture availability, and limited substrate depth. Plants have a variety of physiological responses to these unique conditions, but little is known about how green roof growing conditions affect ecological characteristics like plant flowering phenology. Similarly, studies are only just beginning to uncover the degree to which green roofs can provision habitat and support urban biodiversity. We evaluated the flowering phenology and made in-situ pollinator observations of 15 plant taxa growing both on green roof systems and at ground level at the Denver Botanic Gardens over two growing seasons. Using the same study sites, we sampled invertebrate diversity on green roof sites and ground level using pitfall traps. Finally, using a large citizen-science dataset, we evaluated differences in pollinator visitation with a specific focus on plant nativity, cultivated origin, growth form. We found that flowering phenology is substantially earlier on green roofs compared to ground level. We also observed a greater number of pollinators on green roofs early in the season, compared to ground level, presumably due to the availability of flora resources among the observed plant taxa. We observed significantly higher substrate temperatures along with wider diurnal temperature amplitude during the growing season that may contribute to this pattern. Invertebrate abundance was substantially higher at ground-level, species richness was similar between the intensive green roof and ground-level, and we observed substantially lower abundance and richness on the extensive green roof. Divergence in flowering phenology between individual plants of the same species on green roofs and plants at ground-level may have implications for organisms that rely on floral resources in urban environments. Earlier flower initiation on green roofs may provide pollinators with unique foraging opportunities and aid targeted conservation where early-season floral resources are limited. Similarly, results from invertebrate sampling suggest that green roofs, especially intensive roofs with high vegetation coverage, species richness, and habitat heterogeneity may offer invertebrate habitat on par with ground-level urban gardens and may even support unique groups of invertebrate taxa. Our results from our citizen science pollinator observations demonstrate that non-native plants showed similar visitation compared to native plants, but origin was important with selections and species having significantly higher pollinator visitation compared to hybrid plants. Shrubs and herbaceous perennials demonstrated high pollinator visitation compared to other plant growth forms.Item Open Access Investigation of substrate selection and finishing protocols for nursery container production of 13 plant taxa native to the southwestern United States(Colorado State University. Libraries, 2023) Linfield, Allisa, author; Bousselot, Jennifer, advisor; Gu, Mengmeng, committee member; Davis, Jessica, committee member; Shonle, Irene, committee memberNursery-produced native plant taxa are a tool for habitat restoration, and their use extends beyond wildlife areas as urban residents seek to create wildlife corridors. Water conservation concerns and understanding of pollinator decline further motivates use of native plants in cultivated and designed landscapes. Furthermore, increasing awareness around degradation of peatlands, drives consumer interest in sustainably produced plant material using peat-alternative substrates. Growers attempt to meet the demand for native plant material, but protocols for growing these taxa, which are not adapted to thrive in peat-based substrates, are limited. Without finishing protocols for sizing up propagules to retail size, growers, who are limited by time and resources, amend peat-based substrates using trial and error in hopes of achieving favorable growing outcomes. We identified grower practices through a survey of nationwide Plant Select® growers. Based on survey results, we evaluated survivability and plant growth in response to partially replacing peat-based substrate with sand, field soil, a microbial-inoculated compost (MIC), and a green waste compost (GWC). Our results indicated that plant growth response to these substrates is taxon specific. However, only one of the 13 taxa evaluated resulted in a significantly higher plant growth index (PGI) increase in the control group. Thus, our findings suggest that 12 of the investigated taxa may respond to peat-reduced substrates during the finishing period without significant negative impacts on PGI or dry weight.Item Open Access Plant growth under photovoltaic arrays of varying transparencies – a study of plant response to light and shadow in agrivoltaic systems(Colorado State University. Libraries, 2023) Hickey, Thomas, author; Bousselot, Jennifer, advisor; Uchanski, Mark, advisor; Harrow, Del, committee memberAmidst the rising global pressures put on the interdependent systems in the food, energy, and water nexus, this document highlights the potential for systems-based solutions at the intersection of food cultivation, ecosystem services, and energy production in urban and rural environments. Agrivoltaics (APV) is a land-use model that enables simultaneous cultivation of food crops and electricity generation on the same plot of land. Agrivoltaic systems integrate solar photovoltaic (PV) energy generation with agricultural operations, maximizing the utilization of solar energy. This approach has gained significant research interest in the United States with scalable implementation is on the horizon. Research efforts at Colorado State University (CSU) aim to advance the understanding of plant responses to various shade conditions under PV arrays, benefiting stakeholders in agriculture, solar energy industries, policymakers, and governmental agencies. In particular, agrivoltaic research conducted at CSU's Horticulture and Landscape Architecture (HLA) department has focused on open field specialty crops and native pollinator plant species while documenting the overarching light and temperature growing environment. A replicated 2-year crop trial was conducted at the open field test site, comparing crop yield and growing conditions under three different PV module types with varying transparencies to traditional full sun production. Statistical analysis revealed a reduction in squash yield directly under the PV panels while no significant differences in yield for bell peppers, jalapeno peppers, lettuce and tomatoes growing north and south of the arrays. In a separate study, a simulated green roof structure was constructed around an existing PV array at CSU's Foothills Campus to explore the feasibility of rooftop agrivoltaics. A one-year study of six native pollinator plant species was conducted to assess differences in establishment, survivability, growth index, and growing conditions between full sun and PV shade environments. Overall, there were no statistically significant differences in mean Plant Growth Index (PGI) throughout the establishment season, however, notable variations in overwinter survivability were observed. In both studies the PV modules moderated the environment, resulting in lower maximum daytime ambient temperatures and even greater reduction in soil temperature throughout the growing season. Light levels are reduced under all PV module types with the least reduction under semi-transparent modules. Variations in growing conditions in these APV systems indicate the need for further research to optimize PV systems in order to maximize energy production and plant vitality.Item Open Access Quantitative analysis of runoff in green roof structures in the Colorado Front Range(Colorado State University. Libraries, 2023) Salerno, Amanda, author; Bousselot, Jennifer, advisor; Choi, Jane, committee member; Sharvelle, Sybil, committee memberThe green roof capacity of retaining rainwater extends the runoff duration further than the actual rain event, releasing part of it slowly into the drainage system and positively impacting it. However, the volumes will depend on the size of the rainfall event and the green roof design. Therefore, specific attention should be paid when designing a new green roof project, like geographic locations, materials peculiarities, and the project's needs, including biotic and abiotic design components. The need for more local data regarding this analysis in Western North America is still significant. Therefore, this study aims to analyze the impact of three different green roof systems on Colorado's climate by reduction of runoff, retention volume, and runoff coefficient. Moreover, we aim to analyze plant health and substrate moisture retention and components for better water capture. To achieve the goals outlined, three different green roofs technologies, with different retention and detention layers technologies, and a control roof, a conventional low slope roof for comparison, are placed at Colorado State University in Fort Collins, Colorado, United States; the systems include a Sempergreen Purple Roof, a Sempergreen Sponge Roof, and a Green Roof Technology with an Extenduct Drainage System; all were vegetated with Sedum mats, base slopes of 1% toward the rooftop drain, and measuring 1m x 2m. The drainage systems in each green roof were designed to test performance under steady, low-intensity, high-intensity, short-duration, and long-duration rainfall conditions and simulated rain events. All the systems have the same drain system connected to a v-notch weir. Volume, speed, and time were measured to quantify the runoff from all roof systems. Our data suggests that green roof volume capture varies with preexisting substrate moisture conditions, frequency and size of storms, and drainage layer components. Green Roof Technology with an Extenduct Drainage System and Sponge Roof had the best volume retention in less intense, more frequent, and back-to-back rainfall events. On the other hand, Purple Roof performed better for larger rain events that might lead to flooding and urban drainage concerns in cities. Ultimately, the Colorado-specific data from this study will enable the intentional design of green roofs to optimize plant health and water management.Item Open Access The B.C. Farmers' food donation tax credit: investigating usage among farmers' market vendors(Colorado State University. Libraries, 2019) Immell, Tara, author; Bousselot, Jennifer, advisor; Dalsted, Norman, committee member; Smith, Frank, committee memberFrom 2014 to 2016, four Canadian provinces enacted additional tax incentives targeted at farmers who donate fresh agricultural products. These tax laws are described by many as a win-win situation for farmers and people in need. The intention is to encourage farmers to donate. In British Columbia (B.C.), there is very little information released on the utilization of the tax credit. Limited research examining the efficacy of tax credits is available on the financial impacts to farmers and on the availability of fresh food to vulnerable populations. This thesis provides an overview of food donation tax credits in Canada and the United States (U.S.) and insight into tax credit utilization in B.C., taking a case study approach. Data was collected from a small sample of farmers who sell at Metro Vancouver farmers' markets and food organization managers in British Columbia, using surveys and personal interviews. Results show that B.C. farmers donate food to help people in need and are not aware of, or motivated by, the tax credit. Those not currently donating are primarily concerned about potential additional expenses, especially related to human resources and transportation. In conclusion, programs encouraging farmers to donate need to reduce the time and costs required to donate. To both increase awareness of the credit and to illustrate the financial benefit, future research should provide examples of farmers claiming this tax credit. In addition, a study to document remaining fresh agricultural products at the close of farmers' markets would further inform policymakers about potential donations.