Seeing the Volcano for the Trees

by | Nov 10, 2021 | Daily Space, Earth | 0 comments

Seeing the Volcano for the Trees
IMAGE: In 2001 on Italy’s Mount Etna, a thin line of pine trees started turning greener and greener, suggesting they were photosynthesizing more than their neighbors were. CREDIT: Alessandro Squassoni/Pixabay

This story feels like an amalgamation of so many stories we’ve covered before it. Satellite images? Check. Tree cores? Check. Volcanoes? Check. And all of it adds up to a newly rediscovered bit of information first published in 1975 — something in the soil of a soon-to-erupt volcano can make trees in the region greener than usual.

New research published in the journal Ecohydrology takes a look at how a narrow band of trees, 30 meters wide by 2 kilometers long, on Mount Etna in Italy turned greener in 2001, just before an eruption in 2002 along that same strip. The trees, of course, were destroyed in the eruption, and the difference in greenery was really only noticeable in satellite images. This led researchers to look at some historical observations, including a similar phenomenon that occurred at Mt. Etna back in 1973.

Additionally, further evidence for the phenomenon was found in images at Mount Nyiragongo in the Democratic Republic of the Congo in 2001 as well which was also followed by an eruption.

Of course, satellite imagery isn’t enough to understand what is going on, so the team collected some tree cores with the help of the Swiss National Science Foundation. Since the trees along the eruption zone were destroyed, they focused on trees within 150 meters of the 2002 eruption at Mt. Etna. After an analysis of the carbon isotopes, the results showed that the tree rings were similar during a control period as well as the eruptive period, so the greening effect was not the result of carbon dioxide. However, another isotope, oxygen-18, was shown to drop during the eruption season, and that could mean that the enhanced trees received more water vapor from volcanic steam in the soil.

Now this doesn’t mean that we should hunt satellite images for lines of enhanced trees, although perhaps the new Landsat 9 will be able to do just that. But this is another tool in the box for predicting where a volcanic eruption will occur.

We love multidisciplinary science, and this team involved experts in “forestry, soil science, volcanology, biochemistry, and ecology.” Plus satellite imagery, fieldwork, and lab work. We hope to see more from this group, and we’ll bring it here to you on Daily Space.

More Information

Supergreen Trees Can Signal Sites of Eruptions (Eos)

Tree-ring stable isotopes and radiocarbon reveal pre- and post-eruption effects of volcanic processes on trees on Mt. Etna (Sicily, Italy),” Ruedi Seiler et al., 2021 August 17, Ecohydrology


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