Effect of acid rain on pine needles as food for capercaillie in winter.

The effects of long-range air pollution on the chemical composition of needles of Scots pinePinus sylvestris and consequences for capercaillieTetrao urogallus feeding on the needles were studied. Samples of pine needles from localities receiving different amounts of acid rain were taken in early March. Concentrations of N and P were highest in needles from the most acidified areas, and N concentration was 35% higher in the most heavily polluted area than in the least polluted. Secondary chemicals decreased significantly with increasing acidification. Concentrations of Cd in pine needles were closely correlated with the acid deposition levels, with highest concentrations in the most polluted area. Al concentration also increased with increasing acidification. These results provide evidence that acid rain increases the nutritive value of pine needles through a fertilizing effect. Enhanced levels of certain metals are considered too low to be directly toxic to capercaillie. However, behavioural anomalies cannot be excluded.