Lichenized fungi are widely used as bioindicators owing to their sensitivity to various anthropogenic impacts. Increased nitrogen deposition affects the occurrence, abundance and distribution of lichens. The main sources of nitrogen in the agricultural landscape are ammonia (NH₃) and the ammonium cation (NH₄⁺). Livestock farming and the use of organic and mineral fertilizers are primarily responsible for the emissions of these compounds. N in excess can negatively impact lichen biota and lead, for example, to species decline, impoverishment of lichen communities or unbalanced symbiosis. However, there is also evidence for certain opposite effects, in particular at medium N concentrations. Positive influences may be manifested, for example, by higher chlorophyll a concentrations, or by a greater lichen diversity being supported by the coexistence of lichens with different trophic requirements. Indicator values of lichens in relation to N input are exhibited, for example, by some biont markers (the contents of ergosterol and chlorophyll a), particular species, such as Xanthoriaparietina, or trophic functional groups (oligotrophilous and nitrophilous lichens). Gaps identified in the current knowledge are discussed.

中文翻译：

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农业景观中的氮污染对地衣的影响：其在群落，物种，生物体和生理水平上的反应综述

地衣真菌由于其对各种人为影响的敏感性而被广泛用作生物指示剂。氮沉积增加会影响地衣的发生，丰度和分布。农业景观中氮的主要来源是氨（NH ₃）和铵阳离子（NH ₄ ⁺）。畜牧业以及有机和矿物肥料的使用是造成这些化合物排放的主要原因。过量的氮会对地衣生物区产生不利影响，并导致例如物种减少，地衣群落贫困或共生失衡。但是，也有证据表明某些相反的作用，特别是在中等氮浓度下。例如，较高的叶绿素a浓度或具有不同营养需求的地衣的共存可支持更大的地衣多样性，从而可以显示出积极的影响。相对于N个输入地衣指示符值被表现，例如，通过一些biont标记（麦角固醇和叶绿素a的内容），特定的物种，如Xanthoria parietina或营养性官能团（低亲和地衣性地衣）。讨论了当前知识中发现的差距。