Effects of coniferous resin on fungal biomass and mineralisation processes in wood ant nest materials

 Wood ants (Formica rufa group) often bring large quantities of conifer resin to their mounds. The aim of this study was to test the hypothesis that the resin acts as a fungicide and thereby reduces C and N mineralisation. Two laboratory incubation experiments were carried out using two different materials: F/H layer from a Scots pine (Pinus sylvestris) stand and mixed litter from Scots pine and Norway spruce (Picea abies) stands. We estimated the effects of resin addition on fungal biomass and on the rates of C and N mineralisation. Addition of resin to the F/H material caused an increase in fungal biomass and C mineralisation, whereas N mineralisation decreased. Addition of resin to litter material did not significantly affect fungal biomass or C and N mineralisation. The results indicate that rather than having a fungicidal effect, resin acts as a C source that increases C mineralisation (mainly from the resin itself) and decreases net N mineralisation. The latter factor might be important in preventing plants dependent on inorganic N from invading and covering the ant mounds. Received: 17 December 1998