The input of phosphorus from food and from decomposing litter into the nest of wood ants (Formica polyctena) was studied and compared with the phosphorus input into the humus horizon of surrounding soil in a spruce (Picea abies) plantation. The release of phosphorus from food brought into one ant nest was 75 g P nest(-1) year(-1). P release from decomposed spruce needles incorporated into the nest was 23 g P nest(-1) year(-1). The density of nests in the studied plot was 5 per hectare and the nest covered 0.2% of plot surface. 490 g P ha(-1) year(-1) was released into the nests and 800 g P ha(-1) year(-1) was released in the humus horizon of surrounding soil. High release of phosphorus in the ant nests was connected with the large input of P with food, and with fast decomposition of organic matter inside the nests. In comparison with the surrounding soil a higher decomposition rate of autochthonous material, higher respiration activity and higher microbial counts (colony forming units) were established in the nests.