Högskolan i Skövde

Lichen cover and diversity was analysed on the dwarf shrub Helianthemum oelandicum (L.) Dum.Cours.at one site in the calcareous grassland of the area known as the 'Great Alvar' on the Island of Öland, Sweden. The age of 22 phorophytes was determined by ring counting and varied from 8 to 41 years and was accurately predicted by the root diameter. A total of 18 lichen species were found, with a range between 0 and 13 species per phorophyte. The number of lichen species on living H. oelandicum was correlated with the phorophyte age. The number of lichen species and their coverage was greater on dead compared with living phorophytes. The species number was also higher on thin branches compared with thick branches and roots and some of the species showed preferences for dead phorophytes, and for thin branches. This study of lichen colonization and growth on dwarf shrubs in relation to phorophyte age is a new application of herbchronology.