Lichens don't lie

Tobias Reijngoud writes me that he briefly studied lichens ten years ago during his years at Utrecht University (Fysische Geografie). Lichens were used to estimate the age of monuments they were found on. One of the teachers was a lichen enthusiast. This teacher's college notes title was Lichens don't lie...

I looked but didn't find reference to these college notes online. I did find an article with the same title on the site of the Royal Botanic Garden Edinburgh:

"Cleaner air? Lichens don't lie...

27 May 2004

A rare lichen last seen in Edinburgh in 1797 has made its reappearance in the Garden at Inverleith. RBGE’s resident lichenologists Brian Coppins and Chris Ellis were examining the lichens growing on deciduous rhododendrons in the Azalea lawn when they discovered the gristle lichen, Ramalina fraxinea, attached to a rhododendron stem.

The gristle lichen has declined, sometimes to local extinction, in many parts of Britain due to high levels of sulphur dioxide air pollution prevailing since the Industrial Revolution. It is thought that rigorous and effective measures to reduce air pollution in the last decades have allowed lichens such as this to return to areas where they had previously died off.

The specimen found consisted of several rigid, strap-like lobes, the largest being 8cm long. Under ideal conditions, such as parkland trees in the north east of Scotland, this lichen can attain an impressive length of 30cm."





And another on the site of the French Office of Science and Technology:

Lichens don't lie
proof of nuclear site leakage

Who would you be more willing to believe, France's Atomic Energy Commission or a handful of rootless rock-dwellers? A report published in the Journal of Atmospheric Chemistry has sided with the latter, after several years studying lichen from the area surrounding the CEA's site near Dijon in northern Burgundy, where the CEA's military branch assembles and dismantles hydrogen bombs. The Valduc site has always claimed to be a model of nuclear cleanliness, but when the CEA in a fit of transparence established an independent association of local officials and scientists to verify these claims, the truth as told by local flora turned out to be other. The sample collection campaign was headed by an amateur mycologist who had won previous distinction by being the first to show – in 1986 – that radioactive air masses from Chernobyl had not magically stopped at the French border (as official utterance would have had it), basing his conclusions on spikes of radioactivity in mushrooms. Results from the lichen samples (having no roots, a lichen absorbs its water from the air, making it a particularly good litmus for atmospheric molecules) showed levels of tritium – the main isotope of hydrogen emitted at Valduc – to be 1000 times higher than normal in the immediate surroundings of the site, 100 times greater four kilometers away in the direction of the prevailing wind, and 10 times greater at 40 kilometers from the site. In response to CEA efforts to typify the local lichen as especially tritium-hungry, an independent group of mycologists carried out similar studies in other nuclear sites, like La Haye, with similar results. One final aspect of the watchdog findings, which requires substantiation, is the results from transplanting Valduc area lichen to non-nuclear regions; the mycologists found that the plant loses half its radioactivity in a year. Working backwards this would put Valduc tritium concentrations twenty years ago at exorbitant levels. (Libération, December 3, p11, Nicolas Chevassus-au-Louis)"