Epiphytes are known to respond sensitively to environmental changes. Because of the tight coupling of epiphytes to atmospheric conditions, changes in the chemical and physical conditions of the atmosphere may be expected to have direct effects on epiphytes (Farmer et al. 1992; Benzing 1998; Zotz & Bader 2009). In temperate regions, non-vascular epiphytes (bryophytes, lichens) have frequently been used as bioindicators of air quality (Hawksworth & Rose 1970). Owing to the lack of a protective cuticle in many bryophytes and lichens, solutions and gases may enter freely into the living tissues of these plants causing sensitive reactions to changes in the environment. By mapping and monitoring the distribution and abundance of non-vascular epiphytes, changes in environmental conditions can be assessed (Van Dobben & De Bakker 1996; Szczepaniak & Biziuk 2003).