Lichens are ecologically important because they are sensitive to the atmospheric pollutants, and this is why they are called bio-indicators. The presence of some substances, such as sulphur dioxide, in the air produces changes in the growth of the lichen. The quality of the environment can be assessed by studying the growth of these organisms. Lichens are organisms that colonise an environment that has just settled. They are therefore the first organisms that we can find, for instance, on the rocks of a landslide or, on the mountains, on the rocks left behind by a withdrawing glacier. With time, lichens grow steadily and by studying their size one can determine the year in which the landslide fell or the rocks were left behind by the glacier. These dates are useful to the geologists to reconstruct historical events, to study and gain an insight of the surrounding environment. Many study projects on the movements of Alpine glaciers also rely on this dating system

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From the Multimedia section


  • 13 May 2011

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