title: Time- and dose-dependency of the effects of nitrogen pollution on lichens.
abstract: The present work aims at testing if exposure time and dose play a role in the response of lichen species to nitrogen (N) pollution. To this purpose, samples of the N-sensitive Evernia prunastri and the N-tolerant Xanthoria parietina were treated for 5 weeks either with solutions of NH(4)NO(3) 0.05 and 1 M, or (NH(4))(2)SO(4) 0.025 and 0.5 M. Photosynthetic efficiency was measured as an indicator of sample vitality. The results showed that the lowest concentrations were ineffective at the beginning, but after several supplies both compounds inhibited photosynthetic activity of E. prunastri. The highest concentrations had a deleterious effect, but with a temporal trend. For X. parietina no effect was found for the lowest concentrations, while the same trend shown by E. prunastri was instead observed following treatments with the highest concentrations. It was concluded that the response of lichens to N supply is not only species-specific, but also time- and dose-dependent. The results give a clue on field studies on the relationships between lichens and N pollution.
authors: Department of Environmental Science, University of Siena, via Mattioli 4, 53100 Siena, Italy. munzi@unisi.it
authors: Silvana
authors: S
authors: Munzi
authors: Tommaso
authors: T
authors: Pisani
authors: Luca
authors: L
authors: Paoli
authors: Stefano
authors: S
authors: Loppi
mesh_terms: D000645:Ammonium Sulfate; D000704:Analysis of Variance; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D004785:Environmental Pollutants / Q000633:toxicity*; D008011:Lichens / Q000187:drug effects*; D009566:Nitrates; D009584:Nitrogen / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects*; D013045:Species Specificity; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D009566:Nitrates; D009584:Nitrogen; D000645:Ammonium Sulfate; C006568:ammonium nitrate