On hold

from 01/01/2020 until 31/12/2020

Liquencity·2 represents the continuation of the citizen science LiquenCity (more information at, in which more than 2,000 people participated in the cities of Madrid and Barcelona. In this new project, we expand the framework to three new cities in northern Spain: Oviedo, Pamplona and Pontevedra. The following institutions are involved: the Royal Botanical Garden of Madrid (CSIC), the Spanish Biodiversity Information Node (GBIF.ES), the University of Vigo, the University of Oviedo, the University of Navarra, the Terrabiota association of Pamplona, the University of Barcelona and the Institute of Marine Sciences (CSIC). Air pollution is one of the major problems facing big and medium city inhabitants. The burning of fossil fuels in vehicles, heating systems and industry generates numerous contaminating compounds - especially nitrogen oxides (NOx) and particulate matter - which suppose a serious problem for human health. It has been demonstrated that, in high concentrations, these compounds generate multiple respiratory and cardiovascular diseases, and they are responsible for around 800,000 deaths per year in Europe. The grounds of this project are based on the role of lichen species as bioindicators of different levels of air pollution. Lichens are complex symbiotic organisms formed by the union of a fungus and at least one photosynthetic partner, green algae and/or cyanobacteria. Lichens have been used for decades as bioindicators of anthropic disturbances, especially air pollution. Sensibility to disturbances vary among species, though, and it is possible to identify species with a range of preferences regarding levels of certain pollutants. Overall, it is generally accepted that the greater the diversity of lichens, the better the air quality. Liquencity·2 use nine indicator species growing on trees in each city, which reflect three different levels of tolerance to air pollution. To map species distribution, and therefore air quality history distribution, the project involves the educative communities (teacher training centers, teachers, students mainly from high schools) and other agents in local communities. Using the information provided in our web site ( and the new app for mobile devices, participants can record the observations and take pictures of them, in order to be corroborated by a team of lichen experts. Didactic resources available from the Liquencity·2 webpage allow to work at the classroom topics regarding natural science, air pollution, bioindicator organisms, and lichen biology, enhancing and contributing to the scientific and environmental education of students Information gathered in all three cities will help scientists to build detailed maps of air pollution that will be transferred to local stakeholders, schools and NGOs. The lichen observations will be freely available at the Global Biodiversity Information Facility (GBIF).


The goal of Liquencity·2 is to use bioindicator lichen species to produce air quality maps for three cities of Northern Spain (Oviedo, Pamplona and Pontevedra), involving educational communities (teacher training centers, teachers, students…) in a citizen science project. Lichen occurrence data will be gathered by citizen volunteers using an exclusive app for mobile devices, which guides data collection. This project is the continuation of the successful LiquenCity, which through citizen participation from Madrid and Barcelona cities, almost 5000 records of lichens were gathered in both cities in 2018 and 2019. Besides air quality maps, the project has three specific secondary goals: 1) to raise public awareness of the problem of pollution in cities for public health through the observation of sensitive organisms in an urban ecosystem; 2) to make citizens conscious of the need for pollution mitigation measures; and 3) to spread the knowledge about lichens, their biology and their use as indicator of human perturbances on ecosystems.

Needed equipment

Only a mobile device with camera (smartphone, tablet…) is needed. Observations are recorded in the field (street, park, garden, schoolyard…) and can be uploaded in situ or later with an internet connection. Recording lichens is simple. You just have to look for them in the trees of your city and use Liquencity·2 app in your mobile device, available for both iPhone and Android. The aim of this application is to guide and assist the participant in the recording of lichens. Liquencity·2 app has an intuitive environment and will guide you through the record of the indicator species we seek in each city. Within the app you can find two short cartoon clips explaining the project and the recording of lichens. Besides, you will have information and pictures of the target species and the trees where you can find them in each city. You just have to follow the instructions and to take a picture of the tree where the lichen are, other picture of the lichen species you find and an estimated abundance. At you can also download cards for all species in a printable format as well as project brochures and poster. Teachers and environmental educators can download other didactic resources and materials to introduce lichens, biomonitoring and citizen science in the classroom. Once observations are uploaded, a team of experts will corroborate or correct the observation, so you can check whether your identification was correct.

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Created April 29, 2020, 6:24 p.m.

Updated Dec. 8, 2021, 12:24 p.m.

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