Landscape context strongly influences arthropods but effects may differ based on unique life history strategies and the scale of the analysis. Most research on landscape context effects has focused on one taxa or functional group, yet assessing how changes in landscape composition affect several arthropod taxa can suggest patterns in ecosystem services, and provide information for land management. This research asked how differences in landscape context affect the abundance and taxonomic richness of five urban arthropod groups that provide pollination and predation services in urban agricultural systems (ants, bees, ladybeetles, parasitoids, and spiders). We aimed to determine if and how arthropod populations respond to changes in landscape composition (measured as landscape diversity) and landscape intensification (measured as percent urban area), and how responses may differ with spatial scale. We conducted a scale analysis to assess the strength of correlation between landscape diversity and intensification, and arthropod abundance and richness at 13 spatial scales (200 m - 5 km) using data compiled over three years in urban community gardens in the California Central Coast.
We found that arthropod groups vary in the strength and direction of response to differences in landscape context across spatial scales. However, we did not find consistent, universal trends between landscape factors and arthropod abundance and richness. In general, arthropods seem to respond more or less strongly to changes in landscape diversity and intensification at smaller or larger spatial scales, and differences correspond to their dispersal capabilities. Groups with greater dispersal capabilities responded more strongly to landscape context at larger spatial scales, while those with limited dispersal abilities either responded stronger at smaller spatial scales or did not respond to landscape changes at all. We found that ladybeetle abundance, parasitoid abundance, and ant abundance and richness to be negatively correlated with greater landscape diversity at larger spatial scales, and we found a strong negative correlation between bee abundance and landscape intensification within their foraging range (<2 km). In sum, biodiversity patterns across urban landscapes may be explained by arthropod dispersal ability, yet patterns may also be a function of local habitat quality and availability. Given our findings, we suggest that urban management should consider the significance of managed green spaces within cities to provide resources and habitat for foraging urban arthropods across the landscape.