Population Ecology

, Volume 44, Issue 2, pp 113-120

First online:

Long-term responses in arctic ungulate dynamics to changes in climatic and trophic processes

  • M. C. ForchhammerAffiliated withDepartment of Population Ecology, Zoological Institute, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark Tel. +45-3532-1255; Fax +45-3532-1250 e-mail: mcforchhammer@zi.ku.dk
  • , E. PostAffiliated withDepartment of Biology, Pennsylvania State University, University Park, USA
  • , N. C. StensethAffiliated withDivision of Zoology, Deparment of Biology, University of Oslo, Oslo, Norway
  • , D. M. BoertmannAffiliated withDepartment of Arctic Environment, National Environmental Research Institute, Copenhagen, Denmark

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 Following predictions from climatic general circulation models, the effects of perturbations in global climate are expected to be most pronounced in the Northern Hemisphere. Elaborating on a recently developed plant–herbivore–climate model, we explore statistically how different winter climate regimes and density-dependent processes during the past century have affected population dynamics of two arctic ungulate species. Our analyses were performed on the dynamics of six muskox and six caribou populations. In muskoxen, variation in winter climate, mediated through the North Atlantic Oscillation (NAO), explained up to 24% of the variation in interannual abundance, whereas in caribou up to 16% was explained by the NAO. Muskoxen responded negatively following warm and snowy winters, whereas caribou responded negatively to dry winters. Direct and delayed density dependence was recorded in most populations and explained up to 32% and 90% of variations in abundance of muskoxen and caribou, respectively.

Key words Caribou Density dependence Muskox North Atlantic Oscillation Winter climate