The impact of wood ants (Formica rufa) on the distribution and abundance of ground beetles (Coleoptera: Carabidae) in a Scots pine plantation

1. The importance of wood ants (Formica rufa) in determining the community structure and small-scale species distribution patterns of carabids was examined in a mature Scots pine stand in the New Forest, southern England. 2. Of all measured variables, wood ant density had the greatest impact on the carabid community, with significantly lower numbers of most species occurring where wood ant density was high. 3. Areas of high wood ant density were characterised by low abundance and species richness of carabids and high percentage dominance by the most commonly sampled species, Abax parallelepipedus. 4. The extent and type of vegetation cover was found to influence the distribution and abundance patterns of certain carabid species but only in areas where the density of wood ants was low. Large-bodied species occurred more frequently in bracken-dominated patches where the litter layer was deeper and the density of some potential prey items was higher 5. It is concluded that high densities of wood ants prevent the majority of carabid species from responding to differences in local habitat conditions. Interactions with wood ants must therefore be taken into account in any study examining the impact of habitat variables on carabid distribution and abundance patterns.