This study investigated the relationship between nitrogen and carbon in the thalli of the lichen Evernia prunastri, with an emphasis on the role of the C/N balance in the response of this species to N excess. | Turkish Journal of Biology Turk J Biol (2013) 37: 165-170 © TÜBİTAK doi: Research Article Effect of nitrogen supply on the C/N balance in the lichen Evernia prunastri (L.) Ach. 1,2, 2 2,3 2 2 Silvana MUNZI *, Tommaso PISANI , Luca PAOLI , Monia RENZI , Stefano LOPPI University of Lisbon, Center for Environmental Biology, Campo Grande, Bloco C2, 1749-016 Lisbon, Portugal 2 Department of Environmental Science, University of Siena, via . Mattioli 4, I-53100 Siena, Italy 3 Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, 845 23 Bratislava, Slovakia 1 Received: Accepted: Published Online: Printed: Abstract: This study investigated the relationship between nitrogen and carbon in the thalli of the lichen Evernia prunastri, with an emphasis on the role of the C/N balance in the response of this species to N excess. For this purpose, thalli collected at a remote site were sprayed for 5 weeks with NH4NO3 ( and 1 M) and (NH4)2SO4 ( and M) solutions, and later analyzed for their C and N content. The results showed that the total N content of thalli increased and the total C content decreased along with increasing N concentration in the treatment solutions. Consequently, the C/N ratio also significantly decreased in treated samples. The Fv/Fm ratio, taken as a vitality index, turned out to be positively correlated with C content and negatively correlated with N content. It is suggested that N stress is caused by the lack of compensation for elevated ammonium levels with higher C assimilation. It is concluded that E. prunastri is a suitable bioindicator of N pollution and that the C/N ratio deserves further investigation as a promising tool for early warning of N excess. Key words: Ammonium, biomonitoring, fertilization, physiological parameters, symbiosis 1. Introduction The ecological success of symbiotic forms of life is .
