Assessing the Structural Connectivity of Host Plants for Pollinators in the Concrete Jungle : A comparison between generalist and specialist species’ possibilities to disperse within the urban area of Säter Municipality, Sweden

Sammanfattning

Habitat loss and fragmentation significantly reduce global biodiversity by disrupting ecosystems and isolating populations, with pollinators being no exception. While generalist species adapt well to urban environments, thriving on diverse food sources, specialist species often face challenges due to their more specific habitat and dietary needs. This study explores the connectivity of the urban green spaces for local pollinators, considering their ecological preferences, in Säter Municipality, Sweden. A field inventory of six insect pollinator species’ host plants species and environmental preferences were conducted, complemented by a survey sent to local residents. The connectivity metrics Patch Cohesion Index (PCI) and Mean Proximity Index (MPI) were used and statistically tested in two ways: (1) a comparison of the structural connectivity of host plants and environmental preferences among all six insect species, using the MPI and PCI values as metrics, with the objective of evaluating whether any of the chosen species displayed a significant deviation in connectivity compared to therest, and (2) a comparison of the structural connectivity of host plants and environmental preferences, in which the MPI and PCI values of generalist species were compared to those of specialist species, to evaluate whether either group exhibited a significant difference. Hotspot maps for host plants and environmental preferences, as well as a coldspot map for physical barriers (buildings), were also generated. The results revealed no significant difference in structural connectivity between generalistand specialist species. However, the hotspot maps showed that the distribution of host plants and environmental preferences is uneven across the city. As no significant differences were found, the results suggest that urban green spaces can support both generalist and specialist species, highlighting their potential to foster biodiversity. The identification of hotspots in older, more vegetated neighborhoods underscores the importance of promoting plant diversity in both new and existing green spaces. Future research should include functional connectivity to better understand movement patterns and identify potential barriers. These findings emphasize the role of urban green spaces in supporting pollinators and ecosystem services, offering valuable insights for urban planning aimed at enhancing biodiversity.