Identifying deviation from naturality of lichen diversity for bioindication purposes

The results of many bioindication studies can be interpreted in terms of deviations from “normal/natural” situations (see chapter 1, this volume). The definition of “normality” or “naturality” is a very difficult one. Here, we shall consider as “natural” those areas which are free from heavy anthropization, and from long-distance transport of important pollution loads. Species richness, cover and frequency of epiphytic lichens are obviously different in different bioclimatic areas, which requires the development of different interpretation scales. The methodology presented here has been developed within the framework of a national programme sponsored by the Italian Environmental Agency (ANPA), to monitor the diversity of epiphytic lichens countrywide, following the approach proposed by Asta et al. (chapter 19, this volume).