Ecological corridors for bat connectivity : A distribution, activity and connectivity assessment of bats species in Karlstad Municipality, Sweden

Sammanfattning

Biodiversity is an essential factor for a resilient ecosystem function. Thus, green infrastructure within urban environments, i.e., habitat quality and connectivity for species, is necessary to maintain a sustainable ecology. Bats play an integral role within ecosystems and are one of the most diverse mammal groups on Earth. However, they face considerable anthropogenic pressures, and many large-scale programs are being developed for their conservation. The municipality of Karlstad, Sweden, has identified bats as species of interest, and is this study inventories of bats in six areas were examined to assess bat species distribution and activity. Furthermore, the connectivity between these areas was assessed in terms of barriers, such as roads, railways and artificial light. Data for species occurrence and bat activity from the inventories was obtained from the Swedish Agriculture University species database and Karlstads Municipality. The ecological model PREBAT was used to generate values of Bat Habitat Index quality (BHI Classes 1-4. 1 = lowest, 4 = highest), as well as a Flight Friction Map regarding the landscape and its barriers within Karlstad. Distribution of species and their activity was revealed to vary significantly among species and among the six areas assessed in this study. This variation could be due to species-specific environmental preferences, habitat degradation, or lack of connectivity. The variation in activity was also apparent when assessing Bat Habitat Index, as only Class 1 and two differed significantly from another; higher BHIs did not show significantly higher activity. Moreover, assessment of corridors revealed that light pollution affects up to 60% of some paths, which may compromise bat movement. Considering these results, it is proposed that long-term monitoring programs for bat species and activity, with more spatially explicit sampling designs, should be implemented in Karlstad. This could lead to enhanced connectivity and further conservation for both the bat taxa and their habitats.