Bug roads: Modeling the green space connectivity and pollinator habitat in a large city using open GIS data and tools

The conservation of native bees and other pollinators is an important consideration for the future of urban sustainability. Parks, urban gardens, cemeteries, and other green spaces can provide habitat space for both native and non-native pollinators in cities. These publicly managed green spaces are not evenly distributed across otherwise inhospitable urban landscapes. Buildings and other human-made structures could act as barriers to the movement of pollinators, especially in highly built-up cities. Little is known about how bees navigate cities, and finding suitable habitat in urban ecosystems may be particularly difficult for native solitary bees, which have small foraging ranges. In this study, we utilized open GIS data as well as open-source software (Quantum GIS and Python) to model the shortest flight paths between parks and other public green spaces in New York City, New York, USA. We also used open light detection and ranging (LiDAR) data to assess plausible pollinator habitat in New York City parks. We found that the majority of straight-line (Euclidean) paths between parks intersected at least one building and that shortest paths around buildings were generally 20% longer than their Euclidean equivalent. We found that most managed properties alone, or within connected clusters, did not have sufficient plausible pollinator habitat to support pollinators with medium foraging distances, which include most solitary native bees. Our findings suggest limited connectivity and potential barriers between managed properties in New York City. Increasing pollinator habitat within smaller managed properties and building green roofs on shorter buildings and establishing stepping stone habitats like tree pits and vacant lots could increase overall green space connectivity. This technique for assessing connectivity between green spaces utilizes open data and tools that can be used by conservationists, planners, and policymakers to explore questions related to supporting pollinators or other species of interest in urban landscapes.