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Lichens are organisms formed by the symbiotic union between a fungus and an algae. Lichens can live in virtually any ecosystem and cover approximately 8% of the Earth’s surface. They can live on rock and tree bark (epiphytes).
Currently, especially in the cities, the air we breathe can be contaminated, although it is a problem that can go unnoticed, since we can not see that pollution. Scientists use bioindicators, which are organisms that can provide information on the degree of contamination. Lichens are good indicators of air quality.
The epiphytes lichens are used as bioindicators to assess air quality and, although they do not give quantitatively accurate information as a measure in an air quality station, they give more complete qualitative information. They also allow us to follow evolution over time.
Xanthoria parietina, a lichen that can be found on both trees (epiphyte) or rocks. (Sergio Pérez Ortega, source: Liquecity.org)
Evernia prunastri, a lichen only found in non polluted habitats (Sergio Pérez Ortega, source: liquencity.org)
Many different lichens in the city indicate a good air quality
It has been scientifically demonstrated that a greater diversity of lichens is directly related to a better quality of the atmosphere and how areas with more respiratory conditions, such as lung cancer, have a high correlation with the loss of lichen diversity.
Not all lichen species have the same sensitivity to contamination. Some are very sensitive, while others may live in the polluted environments of cities.
LET´S WORK!
As already mentioned, the diversity of lichen species informs us about the degree of air pollution. Some of the trees in the Camp de Mart have been selected to count the number of different species of lichen found.
On the other hand, we will look for the presence or absence of a series of lichens in particular whose presence or not in our city can help us determine the degree of contamination.
These 16 lichens make up a list drawn up within the framework of the liquenCity project.
To do your job you will need the color cards of lichens, mobiles (compass and camera zoom) and a metre.
Use this table for surface calculations:
List of species we are looking for.. here
Location of the points to work on:
Material you have to take:
color photocopies of lichens
tape measures
graph paper
mobile phones + Plant Net app + compass app
ribbon
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