The use of native and non-native tree species for foraging and nesting habitat by the wood-ant Formica lugubris (Hymenoptera: Formicidae)

Abstract

Woodland management strategies are increasingly focused on reducing non-native plant species. However, changing the species profile of a habitat can have highly disruptive effects on local ecosystems. An isolated woodland containing a population of the northern wood-ant Formica lugubris Zetterstedt, 1838 was used as a case study to predict the effects on the ants of proposed woodland management focussed on reducing non-native tree species. A habitat survey of the woodlands showed that increased light and presence of the native species oak (Quercus spp.) and birch (Betula spp.) were positive factors for ant presence. In addition a survey of foraging throughout the warm season showed that native oak, birch, pine (Pinus sylvestris) and non-native larch (Larix decidua) and spruce (Picea abies) were heavily used for foraging; mostly in the form of honeydew from aphids. Native beech (Fagus sylvatica) was not used for foraging nor provided suitable nesting habitat. Analysis of the results showed that the ants are not reliant on the nonnative species and that light is important to them. The openings in the canopy formed during selective felling could be beneficial for the establishment of new nests.