Urbanization alters communities of flying arthropods in parks and gardens of a medium-sized city.

Edward Lagucki,Justin D Burdine,Kevin E Mccluney

doi:10.7717/peerj.3620

Abstract

Urbanization transforms undeveloped landscapes into built environments, causing changes in communities and ecological processes. Flying arthropods play important roles in these processes as pollinators, decomposers, and predators, and can be important in structuring food webs. The goal of this study was to identify associations between urbanization and the composition of communities of flying (and floating) arthropods within gardens and parks in a medium-sized mesic city. We predicted that flying arthropod abundance and diversity would respond strongly to percent impervious surface and distance to city center, measurements of urbanization. Flying arthropods were sampled from 30 gardens and parks along an urbanization gradient in Toledo, Ohio, during July and August 2016, using elevated pan traps. A variety of potential predictor variables were also recorded at each site. We collected a total of 2,369 individuals representing nine orders. We found that flying arthropod community composition was associated with percent impervious surface and canopy cover. Overall flying arthropod abundance was negatively associated with percent impervious surface and positively associated with distance to city center. Hymenoptera (bees, wasps, ants), Lepidoptera (moths, butterflies), and Araneae (spiders) were positively associated with distance to city center. Hemiptera (true bugs), Diptera (flies), and Araneae were negatively associated with percent impervious surface. Both distance to city center and percent impervious surface are metrics of urbanization, and this study shows how these factors influence flying arthropod communities in urban gardens and city parks, including significant reductions in taxa that contain pollinators and predators important to urban agriculture and forestry. A variety of environmental factors also showed significant associations with responses (e.g. canopy cover and soil moisture), suggesting these factors may underlie or modulate the urbanization effects. More research is needed to determine mechanisms of change.

Highlights

For the past two centuries, the global population has migrated from rural landscapes into densely populated urban environments
We examine how the abundance, diversity, and composition of flying arthropod communities change with urbanization in urban gardens and city parks
Notes: These results indicate that impervious surface and canopy cover were related to flying arthropod community composition

Summary

Introduction

For the past two centuries, the global population has migrated from rural landscapes into densely populated urban environments. As more people move into urban regions, habitats are transformed into built environments and this impacts biodiversity and ecosystem processes (McKinney, 2008). The process of urbanization fragments landscapes and creates a mosaic of habitat patches of different size, use, and quality. Habitat loss and fragmentation in cities can alter important species interactions, such as plant–pollinator interactions (Harrison & Winfree, 2015). These changes in community structure and species interactions may affect important abiotic and biotic processes, like pollination, nutrient cycling, and decomposition (McIntyre et al, 2001), in the locations where most people live. It is important to understand how urbanization influences organisms in order to maintain the services these organisms provide

Objectives

Methods

Results

Discussion

Conclusion