Occurrence of pollution-sensitive epiphytic lichens in woodlands affected by forest decline: a new hypothesis

Influences of forest dieback on epiphytic lichen vegetation in montane spru ce forests of the Hart Mountains (Northern Germany) are described. The epip hytic lichen vegetation of damaged forest stands consists of more species a nd a higher number of endangered, loss toxitolerant lichen taxa than that o f intact forest stands. Therefore, we tested the hypothesis that concentrat ions of potentially phytotoxic substances in stem flow are lower in damaged stands than in intact stands, because the higher needle surface of the lat ter should result in a higher pollutant interception. In accordance with th is hypothesis, lower concentrations of the elements S, Zn, Al, and Mn and o f hydronium ions were established in the stem flow of a damaged stand compa red to an intact stand under identical climatological conditions. This phen omenon could be a precondition of the higher lichen diversity in the damage d stand.