Proximity to the forest edge affects the production of sexual offspring and colony survival in the red wood ant Formica aquilonia in forest clear-cuts

Abstract

Red wood ants of the Formica rufa group, as well as their nests, form a vital part of the ecosystems of both European and Siberian boreal and temperate forests. It has been well documented that the nests of red wood ants in clear-cuts do not perform as well as those deeper in the forest. However, clear-cuts may not be a homogeneously poor habitat for such forest-dwelling ants because the distance of the nest site to the edge of the remaining forest may be a significant factor affecting the nest performance. In this study, I compared the probability of nest survival and sexual offspring production between the nests of Formica aquilonia (Yarrow, 1955) in a forest edge zone (distance to the forest edge <9.2 m) and a clear-cut centre zone in 18 different clear-cut areas. Although the nests were generally smaller, the probability of sexual offspring production and nest survival was higher among those nests in the edge compared to the centre zone. Since the proximity to the forest edge increased the performance of a nest, selective logging and smaller scale clear-cuts may not be as harmful to red wood ants as clear-cutting over a large area.

Keywords:

• Ants
• boreal forests
• forest edge
• forest management
• logging

Acknowledgements

The author thank A. Freitag, M. Hannerz and an anonymous referee for their comments on the previous draft of the manuscript. H. Hakkarainen assisted in data collection. The Forest Office of Jyväskylä City Council, the Jyväskylä office of UPM Forest Company and a number of private forest owners kindly provided their forest areas for the study. The study was funded by the Kone Foundation and by the Emil Aaltonen Foundation.

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Jouni Sorvari

Current address: Jouni Sorvari, Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland