Managing boreal forest landscapes for flying squirrels

Flying squirrel (Pteromys volans) populations have declined severely during the past few decades and the species has become a focal species in forest management and the conservation debate in Finland. We compared landscape st ructure around known flying squirrel home ranges with randomly chosen fores t sites to determine which landscape patterns characterize the areas occupi ed by the species in northern Finland. We sought to identify the key charac teristics of the landscape that support the remaining flying squirrel popul ations. We analyzed landscape structure within circular areas with 1- and 3 -km radii around 63 forest sites occupied by flying squirrels, and around 9 6 random sites. We applied stepwise analysis of the landscape structure whe re landscapes were built up step-by-step by adding patch types in order of their suitability for the flying squirrel. The land-use and forest-resource data for the analysis were derived form multisource national forest invent ory and imported to a geographical information system. Landscape patch type s were divided into three suitability categories: breeding habitat (mixed s pruce-deciduous forests); dispersal habitat (pine and young forests); and u nsuitable habitat (young sapling stands, open habitats, water). Flying squi rrel landscapes contained more suitable breeding habitat patches and were b etter connected by dispersal habitats than random landscapes. Our results s uggest that for the persistence of the flying squirrel, forest managers sho uld 1) maintain a deciduous mixture, particularly in spruce-dominated fores ts; 2) maintain physical connectivity between optimal breeding habitats; an d 3) impost coarse-grained structures on northeastern Finnish landscapes at current levels of habitat availability.