title: A boreal invasion in response to climate change? Range shifts and community effects in the borderland between forest and tundra.
abstract: It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decline or periodically disrupted dynamics in cyclic populations of small and medium-sized mammals and birds. The first warm spell, 1930-1960, stands out as a period of substantial faunal change. However, in addition to climate warming, suggested drivers of change include land use and other anthropogenic factors. We hypothesize all these drivers interacted, primarily favoring southern generalists. Future research should aim to distinguish between effects of climate and land-use change in boreal and tundra ecosystems.
authors.affiliation: Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden, bodil.elmhagen@zoologi.su.se.
authors.forename: Bodil
authors.initials: B
authors.lastname: Elmhagen
authors.forename: Jonas
authors.initials: J
authors.lastname: Kindberg
authors.forename: Peter
authors.initials: P
authors.lastname: Hellström
authors.forename: Anders
authors.initials: A
authors.lastname: Angerbjörn
mesh_terms: D057231:Climate Change; D017753:Ecosystem; D065928:Forests; D065929:Tundra