Effects of ammonia from livestock farming on lichen photosynthesis Luca Paoli a, b , Stergios Arg. Pirintsos b , Kiriakos Kotzabasis b , Tommaso Pisani a , Eleni Navakoudis b , Stefano Loppi a, * a Department of Environmental Science “G. Sarfatti”, University of Siena, via Mattioli 4, I-53100 Siena, Italy b Department of Biology, University of Crete, 71409 Heraklion, Crete, Greece Ammonia from livestock farming affects lichen photosynthesis. article info Article history: Received 2 September 2009 Received in revised form 11 February 2010 Accepted 13 February 2010 Keywords: Air pollution Arid environments Evernia prunastri JIP-test Pseudevernia furfuracea abstract This study investigated if atmospheric ammonia (NH 3 ) pollution around a sheep farm influences the photosynthetic performance of the lichens Evernia prunastri and Pseudevernia furfuracea. Thalli of both species were transplanted for up to 30 days in a semi-arid region (Crete, Greece), at sites with concentrations of atmospheric ammonia of ca. 60 mg/m 3 (at a sheep farm), ca. 15 mg/m 3 (60 m from the sheep farm) and ca. 2 mg/m 3 (a remote area 5 km away). Lichen photosynthesis was analysed by the chlorophyll a fluorescence emission to identify targets of ammonia pollution. The results indicated that the photosystem II of the two lichens exposed to NH 3 is susceptible to this pollutant in the gas-phase. The parameter PI ABS , a global index of photosynthetic performance that combines in a single expression the three functional steps of the photosynthetic activity (light absorption, excitation energy trapping, and conversion of excitation energy to electron transport) was much more sensitive to NH 3 than the F V /F M ratio, one of the most commonly used stress indicators. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The atmospheric concentration of ammonia (NH 3 ) is often high in countries with intensive agriculture and animal husbandry (Graedel et al., 1995). The major sources of atmospheric NH 3 in Europe are livestock farming, fertilizers and some industrial activ- ities (Asman, 1992). Emissions from livestock farming contain a cocktail of compounds: NH 3 , CO 2 , gaseous amines and dust, including nutrient-containing particles, such as N, P and K, which may modify plant communities (Cape et al., 2009). In the atmo- sphere, ca 30% of NH 3 is converted to ammonium (NH 4 þ ), which may further react, be dispersed with aerosols or be removed from the atmosphere mainly by wet deposition (Asman and Janssen, 1987). NH 3 is the main source of dry deposition of atmospheric N around livestock husbandries, and as a gas it may influence lichen communities composition (Frati et al., 2008). Owing to the fact that atmospheric NH 3 has been widely measured in areas of northern Europe with intensive agriculture and livestock farming (e.g. van Herk, 1999; Sutton et al., 2003, 2009), it has been possible to recognize that nitrophilous epiphytes are positively correlated with NH 3 (Sparrius, 2007) and that NH 3 enhances nitrophilous- and decreases acidophilous epiphytes mainly indirectly by rising bark pH (van Herk, 2001). In particular, prolonged exposures (years) to atmospheric NH 3 concentrations >3 mg/m 3 promotes nitrophilous lichens (van Herk et al., 2003) and rise bark pH of local trees within 2e3 km from a point source (van Herk, 2001). In the Mediterranean area, also dust and dry conditions lead to an increase in bark pH enhancing nitrophilous lichens, most of which are also species of xeric environments (Loppi and De Dominicis, 1996; Loppi et al., 1997), complicating the detection of the effects of N compounds (Frati et al., 2008). Concern for the increasing deposition of NH 3 is mainly focused on biological effects at community level, i.e. when changes or damages to the environment have already occurred. On the other hand, monitoring changes at physiological level may help to detect early stress symptoms. Lichen transplants proved to offer rapid information on occurring stress by the analysis of selected physi- ological parameters (Paoli and Loppi, 2008). The aim of the present study was to test the hypothesis that NH 3 pollution in the Mediterranean area directly influences the photo- synthetic performance of lichens. 2. Materials and methods 2.1. Study area A point source of NH 3 (35  18 0 47 00 N, 25  01 0 40 00 E), represented by a sheep farm, was selected in the lowlands of Northern Crete (Greece), where climate is xero- thermic and more than 125 dry days occur per year. During the experiment (see * Corresponding author. E-mail address: loppi@unisi.it (S. Loppi). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2010.02.008 Environmental Pollution 158 (2010) 2258e2265