Differential response of two acidophytic lichens to increased reactive nitrogen availability

Abstract Lichens are one of the most responsive components ecosystem to reactive forms nitrogen. In this work, we selected lichen genera Cladonia and Usnea , composed terricolous epiphytic lichens respectively, described as sensitive nitrogen, test effects different doses nitrogen on physiological parameters (photobiont mycobiont vitality, chitin quantification, content stable isotopes analysis). The main objectives were check if activation protective mechanisms could be stimulated in case chronic stress (low increase for prolonged time), and, so, a toxicity threshold identified above which these fail. two generally affected by exposure increased availability. However, rangiformis was able maintain functioning at lowest used, whereas thalli become overwhelmed. Moreover, appeared more than photobiont responding lower doses. Although only studies longer duration testing will determine an accurate threshold, results give important clues use biomonitors establishment environmental policies.