Different dominant atmospheric nitrogen species coincide with contrasting physiological responses of Hypogymnia physodes (L.) Nyl. transplanted to rural and urban areas.

Different dominant atmospheric nitrogen species are linked to contrasting physiological responses in Hypogymnia physodes transplanted to urban and rural areas.

• Why it matters: Understanding how nitrogen pollution affects lichens is crucial because their responses depend on nitrogen species, environmental conditions, and stressors, which impacts their use as bioindicators.
• What they did: The study analyzed four physiological parameters—photosystem II efficiency, lipid peroxidation, dehydrogenase activity, and nitrogen accumulation—in lichens transplanted to urban and rural sites during winter and summer, focusing on nitrogen species differences.
• The result: Urban-transplanted lichens showed reduced photosystem II efficiency and higher nitrate levels in winter, while rural samples exhibited higher oxidative stress and intracellular ammonium, indicating that nitrogen species influence physiological stress responses.