The Roles of Plant Diversity and Site Characteristics at Different Spatial Scales in Determining Arthropod Diversity in Urban Community Gardens

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Commodities

Practices

• Crop Production: pollinator habitat
• Natural Resources/Environment: biodiversity
• Pest Management: cultural control
• Sustainable Communities: urban agriculture

Insects and other arthropods are pivotal components of agricultural landscapes. They contribute to ecosystem services such as pollination, but can also cause devastating crop damage as pests. Impacting the effect of their interactions with crops, arthropod diversity is associated with many factors, among which are the local (e.g. plant, plot, field) and landscape (garden, surrounding ecosystems) habitats described by factors including plant diversity and land uses. Though a growing literature investigates the effects of local and landscape factors on the arthropod community, limited research has focused on these dynamics in urban agriculture, a particularly complex and heterogeneous landscape.

This study aims to better understand the effects of plant diversity and site characteristics at different spatial scales on the arthropod community composition in urban community gardens, which are increasingly recognized for their social and ecological benefits. To capture the diversity of agriculturally significant arthropod groups, we will conduct surveys of flower-visiting insects and crop pests in gardens with different plant management intensities across spatial scales. We will collect local and landscape scale site characteristics, such as plant diversity, plot and garden sizes, and the amount of green space in the neighborhood through a combination of on-site observations and remote sensing. By analyzing and determining crucial factors and scales that arthropod communities respond to, we aim to inform sustainable management practices in urban community gardens to optimize beneficial insects and reduce pest impacts while conserving the overall arthropod community through collaborations with urban gardeners, garden managers, and city planners.

Objective 1: To determine the role of plant diversity and site characteristics in affecting overall arthropod diversity (pooled pollinator and pest) in community gardens. Using targeted sampling methods, we will collect pollinators and pests in individual gardeners’ plots to assess arthropod species richness and abundance. We will further collect plant diversity through plant censusing and site characteristics to describe land uses and configurations in individual gardeners’ plots and the gardens. We will address the question by determining the relationships and significance of the relationships between local and landscape factors and arthropod richness and abundance.

Objective 2: To investigate the effect of spatial scales of plant diversity and site characteristics on arthropod diversity (pooled pollinator and pest). By using plant diversity collected at the plot level scale, and the garden plant diversity estimated from the samples of plot level diversity, we will compare the effect size and significance of the effect size of plant diversity at the two levels on arthropod richness and abundance. Site characteristics describing land uses and spatial heterogeneity will be collected at the individual plot level scale, garden level scale, and neighborhood scale (from a buffer distance of the garden) and we will compare the effect size on the arthropod community.

Objective 3: To assess if and how pollinators and pests respond differently to plant diversity and site characteristics at different spatial scales. By examining the two groups independently, we will compare the responses of pollinators and pests to landscape factors.