Damaged Sitka spruce Picea sitchensis in the Black Forest, West Germany. Seen here are second & third year growth; second year (sprigs at right angles to main branch) shows yellowing of the needles, which leads to premature death. The main stem (third year) is denuded of needles for part of its length. The damage is associated with acid rain, the lowering of the pH levels (7 is normal) in rainfall by the addition of manmade pollutants into the atmmosphere. These consist of sulphur dioxide & oxides of nitrogen resulting from the burning of fossil fuels. The impact of acidification on soils, plant & animal life & bodies of water is of growing concern.