COPPER IN SCOTS PINE FORESTS AROUND A HEAVY-METAL SMELTER IN SOUTH-WESTERN FINLAND

Distribution and fluxes of copper within Pinus sylvestris stands were studied during 1992 - 1994 along a heavy-metal pollution gradient in s outh-western Finland. The stands are situated at distances of 0.5, 4 a cid 8 km from a copper-nickel smelter that started operating in 1945 a t Harjavalta. According to the results, copper concentrations in the s oil, in the understorey vegetation and in the trees increased steeply towards the smelter. Almost 50 years' accumulation of heavy metals in the soil has caused direct toxic effects to soil microbes, thus decrea sing decomposition and nutrient mineralisation. During the past few ye ars, sulphur and heavy metal emissions ham the copper and nickel smelt er have been radically decreased. However, the heavy metals which have been accumulating in the soil for decades continue to affect the vege tation for a long time through soil processes. Consequently, long-term accumulation in the soil has to be taken into account when determinin g the critical loads of forest ecosystems for heavy metals.