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

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.