Voles and their trophic interactions in a changing landscape

• Main Author: Savola, Sakeri
• Other Authors: Ecke, Frauke, University of Helsinki, Faculty of Biological and Environmental Sciences, Department of Biosciences, Ecology and Evolutionary Biology, Helsingin yliopisto, bio- ja ympäristötieteellinen tiedekunta, biotieteiden laitos, Helsingfors universitet, bio- och miljövetenskapliga fakulteten, biovetenskapliga institutionen, Henttonen, Heikki, Lindén, Harto, Helle, Pekka
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Helsingin yliopisto 2015
• Subjects: ekologia ja evoluutiobiologia; Taivalkoski; Northern Finland; Lynx
• Online Access: http://hdl.handle.net/10138/157566

Approximately 75% of Finland is covered by boreal forest. Intensive commercial forestry has shaped the Finnish landscape as well as the animal communities that inhabit it. It has been suggested that commercial forestry increases the density of voles in boreal ecosystems. Voles, especially those belonging to Microtus, are important prey items for many avian and mammalian predators and are susceptible to numerous pathogens, e.g., Puumala virus In this thesis, I studied the effects of a changing landscape on vole populations and the influence of dynamic vole population densities on other trophic levels in the ecosystem. The main questions in the thesis are: how is commercial forestry affecting small mammal populations?; how does habitat and the small mammal community influence the prevalence of Puumala virus?; what are the main factors regulating red fox (Vulpes vulpes) population density?; and what are the habitat preferences of red fox? In our vole study in Taivalkoski northern Finland we found that the early stages of forest succession are preferred by Microtus and, thus, commercial forestry is increasing the amount of habitat used by Microtus voles. In the Finnish forest landscape, Puumala virus is found in forests of all ages as is its main host, the bank vole. However, the highest bank vole densities are found in mature forests. We also found evidence of a dilution effect in that the incidence of Puumala virus antibodies in breeding bank voles was lower when the abundance of other small mammal species was high. Our results based on Finnish long-term wildlife monitorings suggest that the red fox population is regulated by its main predator, the Eurasian lynx, in addition to its own abundance in the environment. The red fox hunting bag was surprisingly related positively to the red fox population growth. We also found a negative relationship between autumn vole density and fox population growth in the next year. We suggest that the red fox population is affected by both top-down and bottom-up factors. In our ...