STANDARDIZED LICHEN EXPOSURE - CRITICAL-E VALUATION OF THE APPLICATION FOR BIOINDICATION OF IMMISSION EFFECTS

In areas without natural lichen populations because of high levels of air pollution the pollution effects can only be monitored by the activ e method of ''standardized lichen exposure'' according to guideline VD I 3799 part 2 [2]. Connected with a not immission caused total loss of exposed lichens in the investigation area of Munich in 1992/1993 the reliability and application perspectives of this method are critically discussed. Repeatedly acclimatization stress or deep freezing before exposition had been assumed to be the reason for a failure of this act ive method. Future alternative application of the passive method of '' lichen mapping'' should be considered where natural lichen populations still exist - under the aspect of nature protection as well.