Congruent responses to weather variability in high arctic herbivores

Audun Stien,Erik Ropstad,Odd Halvorsen,R Justin Irvine,Leif Egil Loe,Steve D Albon,Nigel G Yoccoz,Rolf A Ims,Eva Fuglei,Vebjørn Veiberg,Rolf Langvatn

doi:10.1098/rsbl.2012.0764

Abstract

Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer (Rangifer tarandus) and sibling voles (Microtus levis), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem.

Highlights

Assessing the role of climatic variation in the dynamics of wildlife populations has become a pressing task in the face of current rapid climate change, in the Arctic [1]
Arctic rodents often show population cycles that are thought to be driven by predator–prey interactions or grazinginduced food quantity cycles [5], while population dynamics of reindeer in predator-free Arctic environments are in general thought to be driven by competition for food, with additional between-year variation in vital rates caused by climatic effects on the quantity and quality of food available [10,11,12,13] and/or parasite abundances [14]
A phenomenon that has the potential to affect both species is ground ice that encases the vegetation and thereby limits access to forage in winter [15,16], with effects propagating through their population dynamics [17,18,19,20], and the web of interactions these herbivores are driving in Arctic ecosystems [3,10,18,21]

Summary

Introduction

Assessing the role of climatic variation in the dynamics of wildlife populations has become a pressing task in the face of current rapid climate change, in the Arctic [1]. 1–2 years) with several large litters per year Such differing life-history traits have been suggested to cause different responses to environmental variation [7,8,9]. We report the results from two long-term studies in the high Arctic that for the first time show evidence for strong temporal synchrony in the population dynamics of reindeer and small rodents. This synchrony is caused by climate forcing, of which ROS events is a main component

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Conclusion