Asynchronous population dynamics of Siberian lemmings across the Palaearctic tundra |
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Authors: | Sam Erlinge Kjell Danell Peter Frodin Dennis Hasselquist Patric Nilsson Eva-Britt Olofsson Mikael Svensson |
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Institution: | Department of Ecology, Animal Ecology, S-22362 Lund, Sweden e-mail: sam.erlinge@zooekol.lu.se, Fax: +46-46-2224716, SE Department of Animal Ecology, Swedish University of Agricultural Sciences, S-90183 Ume?, Sweden, SE
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Abstract: | The synchrony of Siberian lemming (Lemmus sibiricus L.) population dynamics was investigated during a ship-borne expedition along the Palaearctic tundra coast in the summer
of 1994. On 12 sites along the coast from the Kola Peninsula to Wrangel Island, relative densities of lemmings were recorded
using a standardised snap-trapping programme. The phase position of the lemming cycle in each of the studied populations was
determined based on current density estimates, signs of previous density and the age profile of each population (ageing based
on eye lens mass). In addition, dendrochronological methods were used to determine when the last peak in the density of microtine
populations occurred at each site. The examined lemming populations were in different phases of the lemming cycle. Some populations
were in the peak phase, as indicated by high current densities, an age profile in which older individuals were well represented,
and signs of high previous density (abundant old lemming faeces). Other populations were in the decline phase, as reflected
in a moderate current density, a predominance of older individuals and signs of high previous density. Populations in the
low phase had an extremely low current density and showed signs of high previous density, while populations in the increase
phase had a moderate current density, a predominance of younger individuals and showed signs of low previous density. The
results of phase determinations based on dendrochronological methods support the findings based on lemming demography. Recent
Russian studies carried out on some of the sites also agreed with our phase determination results. Thus, on a regional scale
(across the whole Palaearctic tundra), the population dynamics of Siberian lemmings can be considered asynchronous. However,
sites situated adjacent to each other were often phase synchronous, suggesting a more fine-grained pattern of dynamics with
synchrony over distances as long as 1000 km or so, e.g. the Yamal and Taymyr Peninsulas.
Received: 19 August 1998 / Accepted: 1 March 1999 |
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Keywords: | Lemmus sibiricus Cyclic dynamics Palaearctic tundra Regional asynchronous fluctuations |
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