Can ammonia tolerance amongst lichen functional groups be explained by physiological responses

摘要: Ammonia (NH3) empirical critical levels for Europe were re-evaluated in 2009, based mainly on the ecological responses of lichen communities without acknowledging physiological differences between oligotrophic and nitrophytic species. Here, we compare a nitrogen sensitive (Evernia prunastri) with tolerant one (Xanthoria parietina), focussing their response (Fv/Fm) to short-term NH3 exposure frequency occurrence along an field gradient. Both Fv/Fm E. prunastri decreased abruptly above 3 μg m−3 suggesting direct adverse effects its photosynthetic performance. By contrast, X. parietina increased NH3, despite showing capacity photosystem II 50 that success at ammonia-rich sites might be related indirect availability. These results highlight need establish