Traffic represents the main source of pollution in small Mediterranean urban areas as seen by lichen functional groups

Abstract

The land-use type (residential, green areas, and traffic) within relatively small Mediterranean urban areas determines significant changes on lichen diversity, considering species richness and functional groups related to different ecological factors. Those areas with larger volume of traffic hold lower species diversity, in terms of species richness and lichen diversity value (LDV). Traffic areas also affect the composition of the lichen community, which is evidenced by sensitive species. The abundance of species of lichens tolerant to low levels of eutrophication diminishes in traffic areas; oppositely, those areas show a higher abundance of species of lichens tolerating high levels of eutrophication. On the other hand, residential and green areas have an opposite pattern, mainly with species highly tolerant to eutrophication being less abundant than low or moderate ones. The characteristics of tree bark do not seem to affect excessively on lichen composition; however, tree species shows some effect that should be considered in further studies.

Modelling the response of urban lichens to broad-scale changes in air pollution and climate

“…S4), although our data does not allow to disentangle their effects as they co-occur. This is in accordance with what was observed in other studies (Llop et al, 2012;Llop et al, 2017), but was observed for the first time in multiple cities and with broad-scale air pollution. The air pollution model used (EMEP MSC-W) includes not only pollution sources and concentrations, but also climatic information.…”

“…Air pollution has long been a high-intensity driver in urban areas due to the presence of local industrial and traffic pollutants within nearby cities (Babiy et al, 2003;Fenger, 1999), which translates to increased pollutant concentration or deposition (Krzyzanowski et al, 2014;Riga-Karandinos and Saitanis, 2005). Although the role of specific pollutants has been observed in several local-scale studies (Llop et al, 2017;Varela et al, 2018), our results suggest that on a broad scale, when multiple pollutants are superimposed, lichens respond to pollution overall rather than to specific pollutants. Because lichens absorb pollutants from wet and dry atmospheric deposition (Van Der Wat and Forbes, 2015), increased air pollution levels translate to an overall harmful effect on most lichen species, and result in consequent species loss, as reported by several authors in single-city studies (Gary, 2010;Koch et al, 2016;Munzi et al, 2007).…”

Demographic Inequities in Health Outcomes and Air Pollution Exposure in the Atlanta Area and its Relationship to Urban Infrastructure

“…Despite these challenges, air quality in cities is of particular concern as many source apportionment studies have shown that traffic sources are a significant contributor to pollution [16,[34][35][36][37][38][39][40][41][42]. People living in close proximity to roadways are at risk of high exposures to air pollutants [43], and many urban populations of low SES groups typically live close to roadways [17,44,45].…”

Impact of Air Pollution on Terrestrial Ecosystems

“…However, cryptogams in the Mediterranean are not effective biomarkers for changes in water availability induced by climate change because they are affected by several stress factors in similar ways (Pirintsos et al 2011). Lichens have been efficiently used to identify local sources of atmospheric contamination in urban or highly contaminated industrial sites of the Mediterranean countries (Paoli et al 2006;Llop et al 2017;Ratier et al 2018). More rarely used in distant areas, lichen and mosses were successfully used as metal biomonitors in various environmental situations in France and over the last century.…”