Recipient Organization
UNIVERSITY OF COLORADO
(N/A)
BOULDER,CO 80309
Performing Department
(N/A)
Non Technical Summary
Relevance to AFRI priorities: Community gardens are a way to bring fresh produce into low-income urban areas, often referred to as 'food deserts' due to their limited access to fruits and vegetables. However, it is unclear if different ecological contexts surrounding community gardens impact crop yield by altering the quality of arthropod biodiversity-mediated ecosystem services at a site. Studies have shown a correlation between biodiversity and neighborhood income, but it is unclear what environmental mechanisms may drive changes in arthropod community composition. This study aims to address two key questions:(Q1) Are there variations in biodiversity-mediated ecosystem services in community garden sites due to differences in arthropod community composition?(Q2) What urban matrix landscape and socioeconomic characteristics influence these variations?The knowledge gained from this project will help to identify the features of urban agroecosystems most at risk of insufficient ecosystem services and reduced crop yield. This knowledge is important for achieving the Food Safety, Nutrition, and Health program area goals of providing "safe, high quality, and nutritious foods [that] are essential for human health and well-being" and "improving the quality of life for underserved communities."Relevance to predoctoral program: To implement the proposed project, I will partner with the Denver Urban Garden Collective in Denver, CO, and utilize the research facilities and entomological resources at the University of Colorado Boulder. Through this project, I will continue to develop the expertise and skills needed for a career as an academic researcher focusing on applied ecology.
Animal Health Component
0%
Research Effort Categories
Basic
100%
Applied
0%
Developmental
0%
Goals / Objectives
The knowledge gained from this project will help to identify the features of urban agroecosystems most at risk of insufficient ecosystem services and reduced crop yield. This knowledge is important for achieving the Food Safety, Nutrition, and Health program area goals of providing "safe, high quality, and nutritious foods [that] are essential for human health and well-being" and "improving the quality of life for underserved communities."The results of this project will advance urban ecology theory byuncovering explicit links between urban landscapecharacteristics and arthropod biodiversity. Identifying these links will help to ensure the robustness of ecosystemservices in urban agroecosystems, which will help toachieve "food security through increased productionefficiencies" (USDA NIFA).The long-term goals of this type of research are:Conserving arthropod biodiversity in urban areasMaximizing the productivity of urban agroecosystemsIncreasing equity in access to fresh produce in urban centers.
Project Methods
Methods. This study will be conducted at community garden sites affiliated with the Denver Urban Garden Collective (DUG) in Denver, Colorado, which experiences a semi-arid climate. With over 190 DUG gardens available, I have the flexibility to select sites that are dispersed spatially, uniform in size, and exhibit varying levels of impervious surface and socioeconomic conditions in the surrounding matrix, allowing me to tease apart their independent effects. To select sites, I will employ the Generalized Random Tessellation Stratified Spatial Sampling method, which ensures an even spatial distribution of sites and minimizes clustering. A minimum of 2 km will separate each site.To assess pollination services and pest loads, I will introduce experimental cucumber plants of the Cucumis sativus "spacemaster" variety. Cucumbers rely on insect pollination to set fruit. Plants will be cultivated from seed in a temperature-controlled greenhouse at CU. As the plants mature, 30 days after germination, they will be transferred to the community garden sites. Each garden plot will host two plants per plot, with three plots in each garden spanning across 20 garden sites, for a total of 120 cucumber plants. When cucumbers begin to ripen (indicated by a color change ~2 weeks after fruits emerge), I will harvest five fruits from each plant, measuring their fresh weight on an analytical balance and counting the number of seeds (seed set). Additionally, I will evaluate herbivory damage on each cucumber plant at the end of the summer following the Herbivory Variability Network (HerbVar) protocol. I will also count the number of remaining leaves on each plant at the end of summer to account for plants losing leaves to extreme herbivory damage.I will systematically sample arthropod populations with vane traps, pitfall traps, and sticky traps. Arthropods will be collected three times over the course of the summer (late June, July, and August) to capture the full community across the summer season. I will then identify insects to the lowest possible taxonomic level and assign functional categories based on known feeding behaviors. When feeding behavior is unknown for a taxonomic group, I will examine the mouthparts of the individual to estimate dietary preferences (e.g., haustellate mouthparts will be checked for the presence of stylets used for piercing and sucking). Taxonomic identification will rely on dichotomous identification keys, expert consultation, and example specimens from the CU Museum of Natural History Entomology collections. I will collect data on floral resources and bare ground cover in the neighborhoods surrounding the community garden sites. Flowers provide nutrition to pollinators through nectar and pollen while also serving as sites where natural enemies find and consume herbivorous pests. Bareground provides nesting sites, which can be especially important for pollination services, given that over 70% of all bee species are ground nesters. Collecting data on these variables will involve visual surveys along a city block in four transects encircling each garden site and a random selection of homes within 1 km of the site. At each site, I will take pictures of the lawn to estimate floral resources and bare ground later as a percentage of each parcel of land. Land cover data will be used to determine the percentage of impervious surface and tree canopy cover in the neighborhoods around the garden sites. Wealth Index for each site will be extracted from the ESRI database within a 1-km radius of each garden site. This index comprises multiple indicator variables, including income, net worth, and financial well-being, and is scaled so that a value of 100 represents wealth relative to the national average (ESRI 2020). Floral resources, bare ground, and tree canopy cover will be integrated into an overall habitat quality index using principal components analysis.Statistical analyses. I will construct a structural equation model using the piecewiseSEM package in R.Structural equation modeling allows for variables to serveas both predictors and response variables within the samemodel, enabling the examination of direct and indirecteffects within the causal pathway. Utilizing the arthropoddata collected, I will calculate the abundance and richnessof functional guilds across all gardens. Using thesestructural equation models, I will unravel the direct andindirect impacts of urbanization, wealth, arthropod habitatquality, environmental variables, and arthropod functionalcommunity composition on urban crop growth and yield.