Norwegian lemmings, Lemmus lemmus: a case for a strong herbivore–plant interaction
: Oksanen, Lauri; Vuorinen, Katariina E. M.; Kyrö, Kukka; Mäkynen, Aurelia; Olofsson, Johan; Ruffino, Lise; Tuomi, Maria; Oksanen, Tarja
Publisher: Wiley
: HOBOKEN
: 2025
: Ecography
: Ecography
: ECOGRAPHY
: e07297
: 14
: 0906-7590
: 1600-0587
DOI: https://doi.org/10.1111/ecog.07297
: https://doi.org/10.1111/ecog.07297
: https://research.utu.fi/converis/portal/detail/Publication/491381914
In his classical contributions, Olavi Kalela proposed that, due to the low primary productivity of the tundra, Norwegian lemmings are locked in a strong interaction with their winter forage plants. Proposedly, Norwegian lemmings respond to the threat of critical resource depletion by conducting long-range migrations at their population peaks. A tacit premise of this conjecture is that predation pressure on the Fennoscandian tundra is too weak to prevent runaway increases of lemming populations, creating violent boom-crash dynamics. Our results on the dynamics of Norwegian lemmings on the Finnmarksvidda tundra during 1977-2017 are in line with the predictions of Kalela's hypothesis. In contrast to the Siberian and North American tundra, densities of avian predators in our study area have been low even during lemming years, and efficient ones have been lacking from lemming habitats. Lemmings have thus increased unhinged in peak summers and crashed to densities below the trappability threshold during post-peak winters. Each lemming crash has been accompanied by massive habitat destruction. Indications of predator activity have been concentrated to productive shrublands, where lemmings have never reached high densities. Young lemmings have responded to high densities by becoming extremely mobile: they have been trapped in large numbers on islands, including a small island in the middle of Ie & scaron;j & aacute;vri, a 10 x 8 km tundra lake. Many lemmings have been seen swimming across the lake, and many drowned lemmings have been observed. The dynamics and behavior of Norwegian lemmings recorded by us differ radically from those of other Lemmus spp., indicating that cycles generated by lemming-vegetation interactions have two alternative states - one with and the other without intense summer predation. We propose that the cycles of Norwegian lemmings shifted to the latter state during their unique evolutionary history, when they survived the Last Glacial Maximum in a tiny refugium archipelago.
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– During our 40 years of research, our main financiers have been Swedish Research Council and the Academy of Finland. During 2009–2013 we obtained substantial funding from Høgskolen i Finnmark. During 2011–2015 we were also funded by funded by the Norden Top-Level Research Initiative ‘Effect Studies and Adaptation to Climate Change'.
