How trees survive fires

Even when charred, certain trees manage to re-establish buds which can be several decades old, up to 1000 years old, this is what a study carried out on redwoods reveals.

Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon speaks to us today of a small glimmer of hope in the doldrums: a bud growing on a charred trunk.

franceinfo: Some trees manage to survive the worst fires, and researchers are discovering how?

Mathilde Fontez: Yes, these are Californian researchers, who studied the forest, after the big fires of 2020: the flames rose up to 90 meters, incinerating the branches and thorns of the giant sequoias…

Yet they survived. How ? It was the samples and laboratory studies that showed it: these trees drew on buried resources, hidden buds, which had been waiting, protected under the bark, for hundreds of years. It’s a kind of plant hibernation. Some of these buds date back up to 1000 years.

After the fire, when the tree is burned, do these buds develop?

Yes, it’s like a reserve that is released: the bud activates, and a young shoot emerges from the trunk. The researchers discovered that the tree also kept reserves of food, safe from fire: sugars, made when there were leaves, and stored for years, to nourish the buds. In short, the tree has put in place a sort of foresight: it has stored everything it needs to get going again after the worst fire…

Is this the first time we’ve seen this?

We knew that trees, unlike plants, evolved to adapt to the worst hazards: fires, storms. We had seen, for example, that Aleppo pines keep cones in reserve, which only release their seeds under the effect of heat, once the fire has passed.

But redwood is an extreme case. It is particularly adapted to fire: researchers estimate that a 1000-year-old sequoia suffers more than 100 fires. This is undoubtedly why it is the largest tree on the planet: it has sheltered its branches from the flames, at the very top.

It has developed an ultra-resistant bark, which can be up to 30 centimeters thick, and which contains tannic acids, which retard flames. And what’s more, this is what we discovered today: ideployed a reserve system of buds which remain always young, always ready to bloom, for hundreds of years.