Mapping Lichen Diversity as a First Step for Air Quality Assessement

The evaluation of air quality is an important topic. It is well known that lichens have a set of characteristics that make them well suited for biomonitoring purposes. Sampling lichen diversity is not as expensive as chemical analysis and for this reason a dense sampling grid is possible thus reducing the costs of analysis. Lichen diversity can be used to identify more disturbed areas, resulting from pollution, land use or ecological factors. In recent years, in order to enable extended use of lichens and to reduce ambiguities, that is, variations due to unwanted factors, efforts have been made to develop a feasible protocol for lichen sampling for biomonitoring purposes. The objectives of this work were to provide the information needed a priori for an air quality assessment study, in the form of a map showing areas where lichen diversity and abundance is lower. This study was done by sampling foliose and fruticulose lichen diversity and frequency, in a region in southwest Portugal (Sines) with large industrial facilities. A long term study has been underway in the same area since 1970s using lichens as bioindicators to evaluate air quality. In this work we used a standard protocol to determine of a Lichen Diversity Value (LDV), to be used as an indicator of environmental quality. In order to reduce uncertainty concerning the type of disturbance affecting lichens, sampling sites were restricted using well-defined criteria. Whenever possible, sampling site variables were quantified. This method allowed us to reduce the many sources of variability affecting lichen diversity.