Description

The present study attempts to deduce the levels of air-pollution from its effects on epiphytic lichens in the Miinsterland caused by the emission source of the Ruhrgebiet adjacent in the South to the investigated area. For the collection and determination of the values the author has used the lAP-method developed by De Sloover & Le Blanc (I968). A distribution map has been constructed by examin ing the lichen flora of 117 sites located all over an area encompassing about 2 3000 km . Since Malus domestica is relatively abundant in the territory and as it frequent ly stands isolated in the fields, the author decided to study the lichen-flora of this tree species only. At most stations data recorded during the careful examination of 10 trees were considered sufficient to give an adequate picture of the lichen vegetation. The tree boles were investigated at a height of 0.50 m up to 1.50 m in four directions (NW, SW, SE, NE). Basing on the lAP-values the author found it possible to distinguish five zones of atmospheric purity proceeding from South to North and extending from East to West. In some places of the Miinsterland Zone 1 with a pollution maxima has an expansion of 25 km. Only a total of 16 species of epiphytic lichens was recorded in the area investigation while 90 had still been found in 1898."