Long-term effects of air pollutants in Finland have been studied by analyzing needle litter of pine (Pinus silvestris L.) and spruce (Picea abies L. Karst) in 13 stands from the years 1958 to 1982. A considerable annual increase in elemental concentrations was observed in the southern stands where acid deposition is high. No apparent increase was seen in the north, where deposition was low. During recent years the concentration of noble nutrients, especially potssium in the needle litter has started to decrease. The decline seems to be very steep, probably due to acidic processes in soil. © National Research Council of Canada, NRC Research Press. Abstract reproduced by permission.