Epsilon Open Archive

Abstract

With a focus on boreal spruce dominated forests, we here examined the main factors determining species richness of beetles using extensive beetle survey data from Finland. For total species richness, richness of natural spruce forest specialists, and 3 individual species, selected models were used to predict expected species richness and occurrence probability, respectively, in Dalarna. Stand age was found to have positive effects on total beetle richness and natural spruce forest specialist species richness, as well as on the occurrence probability of the red-listed species Tachinus elegans and the indicator species Xylechinus pilosus. Connectivity to old and high volume spruce forest was important for the occurrence of Enicmus planipennis (assuming mean dispersal distance 5km) and X. pi- losus (assuming mean dispersal distance 1km), and, intriguingly, also positively affected total species richness (again assuming a mean dispersal distance of 1km). The availability of high qua¬lity habitat in an area of 100–400 hectares around a focal site thus appeared to be important for high local species richness. Maps of estimated connectivity for three different assumed mean dispersal distances are provided alongside distribution maps for T. elegans, E. planipennis and X. pilosus, as well as maps of expected total species richness and the richness of natural spruce forest specialists. Since maps of old forest connectivity may be generally useful for planning in the context of green infrastructure, further connectivity maps are provided also for old pine forest.