Faculty of Biological and Environmental Sciences, P.O. Box 65 (Viikinkaari 1), FI-00014, University of Helsinki, Finland.
Kuopio Museum of Natural History, Myhkyrinkatu 22, FI-70100 Kuopio, Finland.
Sci Total Environ. 2023 Jun 15;877:162877. doi: 10.1016/j.scitotenv.2023.162877. Epub 2023 Mar 16.
Acidophytic, oligotrophic lichens on tree trunks are widely considered to be the most sensitive biota to elevated concentrations of atmospheric ammonia (NH). We studied the relationships between measured NH concentrations and the composition of macrolichen communities on the acidic bark of Pinus sylvestris and Quercus robur and the base-rich bark of Acer platanoides and Ulmus glabra at ten roadside and ten non-roadside sites in Helsinki, Finland. NH and nitrogen dioxide (NO) concentrations were higher at the roadside than non-roadside sites indicating traffic as the main source of NH and nitrogen oxides (NO). The diversity of oligotrophs on Quercus was lower at the roadside than non-roadside sites, while that of eutrophs was higher. The abundance and presence of oligotrophic acidophytes (e.g., Hypogymnia physodes) decreased with increasing NH concentration (2-year means = 0.15-1.03 μg m) especially on Q. robur, while those of eutrophic/nitrophilous species (e.g., Melanohalea exasperatula, Physcia tenella) increased. The abundance of some nitrophytes seemed to depend only on bark pH, i.e., their abundances were highest on Ulmus, which had the highest average bark pH. Overall, the results of lichen bioindicator studies may depend on tree species (bark pH) and lichen species used in calculating indices describing the air quality impact. Nevertheless, Quercus is recommended to be used to study the impact of NH alone and in combination with NO on lichen communities, because the responses of both oligotrophic acidophytes and eutrophic species can already be observed at NH concentrations below the current critical level.
嗜酸、寡营养型地衣广泛被认为是对大气氨（NH）浓度升高最敏感的生物群。我们研究了在芬兰赫尔辛基的 10 个路边和 10 个非路边地点，测量的 NH 浓度与云杉和欧洲栎、糖槭和欧洲榆树的酸性树皮上大型地衣群落组成之间的关系。路边的 NH 和二氧化氮（NO）浓度高于非路边地点，表明交通是 NH 和氮氧化物（NO）的主要来源。路边栎树上的寡营养型物种的多样性比非路边地点低，而富营养型物种的多样性则更高。贫营养型嗜酸地衣（如 Hypogymnia physodes）的丰度和存在随着 NH 浓度的增加而减少（2 年平均值为 0.15-1.03μg m），尤其是在欧洲栎树上，而富营养型/氮嗜型物种（如 Melanohalea exasperatula、Physcia tenella）的丰度则增加。一些氮嗜生物的丰度似乎只取决于树皮 pH 值，即它们在树皮 pH 值最高的榆树的丰度最高。总的来说，地衣生物指示剂研究的结果可能取决于树种（树皮 pH 值）和用于计算描述空气质量影响的指数的地衣物种。然而，建议单独使用栎树来研究 NH 以及与 NO 结合对地衣群落的影响，因为在当前的临界水平以下，寡营养型嗜酸生物和富营养型物种的反应已经可以观察到。
