Epiphytic lichen vegetation on birch stems was studied in the border area between Norway and Russia. The area is heavily in-  uenced by sulphur dioxide pollution emitted from Russian nickel smelters. Hypogymnia physodes and Melanelia olivacea were the two most abundant lichen species on birch stems in the study area. Their coverage was clearly reduced near the pollution sources. Lichen vegetation cover increased with increasing distance from the pollution source from a ‘lichen desert’ to normal cover levels. A different local pattern of occurrence of the two lichen species was observed. M. olivacea was more abundant and tended to occur on all sides of the trees, whereas H. physodes was largely restricted to northern exposures (NW–NE).