Regional Landscape Patterns and Distribution of the Siberian Flying Squirrel Pteromys volans in Northern Finland

Abstract

Distribution of the Siberian flying squirrel Pteromys volans in northern Finland, at the edge of its global range, is fairly distinctive: the species is apparently absent in the western part of the region (Pohjanmaa), occurs regularly in the central part (Koillismaa), and only sporadically further east closer to the Russian border (northern Kainuu). In this study, we examined landscape structure in these three regions using geographic information system (GIS) and multi‐source land use and cover data to identify key characteristics in landscape structure that are linked to the observed distribution pattern of the Siberian flying squirrel in northern Finland. We analysed landscape structure by studying habitat type proportions in nature reserves and in large‐scale landscape samples within the regions. In addition, landscape configuration and connectivity were analysed within larger landscape sample plots. Our results suggest that the observed distribution pattern is associated with natural patterns in landscape structure at local and regional scales. Open peat lands, bogs and non‐forested habitats dominate the landscape in the western part of the region and possibly account for the absence of the Siberian flying squirrel. More subtle differences between the central and eastern parts of the region indicate regional scale landscape responses of the species. The relatively high amount of spruce‐dominated mixed forests in the central part was associated with the regular occurrence of the Siberian flying squirrel, whereas the increasing dominance of pine forests towards the east was associated with the low number of sightings. Forest management history is much alike in the different parts of the region, but the effects of forest management on the actual range of the species cannot be estimated owing to a lack of knowledge on accurate population trends in northern Finland. However, human‐caused fragmentation and large‐scale habitat degradation may have long‐term effects on the persistence of the species in northern Finland.