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The relationships between red wood ants ( Formica rufa group) and other ground-dwelling arthropods were studied in young managed forests stands in Eastern Finland. The main objectives were: (i) to test the influence of stand type (dominant tree species; age: sapling versus pole stage) and numbers of red wood ants on the occurrence of other ground-dwelling arthropods and (ii) to study the occurrence of red wood ants versus other arthropods on a distance gradient from ant mounds. We used pitfall traps set in 5-14-year-old sapling stands and 30-45-year-old pole-stage stands of Scots pine ( Pinus sylvestris L.) and birch ( Betula spp.) forests., Pitfall trap catches of red wood ants did not vary significantly between the forest stand types, although some groups of other arthropods showed clear responses to stand type (e.g. catches of other Formicinae and Gnaphosidae were higher in sapling stands than in pole-stage stands). The number of red wood ants clearly explained less of the variation in assemblages of other ground-dwelling arthropods than the forest stand type., Red wood ant numbers decreased significantly with distance from the mounds, but the other ground-dwelling arthropods were insensitive to this gradient or even showed a preference for proximity to ant mounds and high ant activity., The results obtained in the present study suggest that wood ants do not have strong effects on several other ground-dwelling arthropod groups in young managed forests other than in the immediate vicinity of their mounds. [ABSTRACT FROM AUTHOR]

Red wood ants ( Formica rufa group, RWAs) are common insects in boreal forests in Fennoscandia, and they build large, long-lived mounds as their nests. RWA mounds are enriched with carbon and nutrients, but little information is available about how they affect root distribution and the nutrient uptake of trees. In this study, we investigated the biomass, biomass density, nutrient concentrations, and amounts of fine (<2 mm) and coarse (>2 mm) roots in RWA mounds, and compared them with those of surrounding forest soil in mixed coniferous stands of different age classes in Finland. Neither fine nor coarse root biomasses differed significantly between the aboveground parts of the mounds and the organic layer of the soil. Root biomass density was lower in mounds than in the organic layer. However, fine root biomass and biomass density were higher in the belowground parts of mounds than in the surrounding mineral soil. Macroelement (N, Ca, K, P, S, Mg) and Zn and Cu concentrations in roots in the mounds were significantly higher than those in the organic layer. Root biomass and biomass density did not differ between stands of different age classes. The results of this study indicate that RWA mounds increase heterogeneity in root distribution in forest ecosystems, and also increase the availability of nutrients for plants that extend their roots inside RWA mounds. [ABSTRACT FROM AUTHOR]