Evaluation of lichen diversity as an indicator of environmental quality in the North Adriatic submediterranean region.

In 2000, a standardized sampling protocol was developed by a group of European researchers to provide a repeatable and objective strategy for mapping lichen diversity as an indicator of environmental changes; this protocol is nowadays adopted in the guidelines to air quality bioindication in Italy. The present paper shows the results of a study of epiphytic lichen diversity performed according to both the new protocol and the standard methodology previously used in Italy; diversity values are based on frequency counts of all lichen species within particular sampling grids positioned on the trunks and divided in subunits. The survey was carried out in 61 sampling sites of two areas of the Friuli Venezia Giulia region (Italy) and Slovenia, characterized by similar climatic conditions and a wide range of anthropic pressure. Biodiversity values obtained following the two sampling methods are highly statistically correlated; this suggests an interpretative continuity of lichen diversity data for biomonitoring purposes. Lichen communities and diversity values occurring in natural areas, far from heavy human influences, are investigated by means of multivariate analysis of floristic releves of 11 sites. Diversity values scored in natural areas are rather variable, and are mainly influenced by the different vegetation types, Parmelion communities having lower diversity values than communities with Xanthorion elements. Evaluation scales of environmental alteration based on lichen diversity in the North Adriatic submediterranean bioclimatic area are provided. Some critical aspects of the sampling strategies are discussed.