Trees & Flames

The particularly thick bark of the cork oak (Quercus suber) keeps the living tissue in its trunk (the part of it that transports water and nutrients) away from the heat. As a result, fire weakens the tree but doesn't kill it.

Over the millennia, some forests have learned to live with fire. Some of the trees that make up the forests have developed their own strategy to resist flames or be reborn from the ashes.

But that's an exception to the rule! The vast majority of deciduous trees come back to life by producing new shoots that sprout after the fire.

These shoots start to grow out of the dormant buds under the bark where the stump is still alive, sometimes along the trunk, and even at the crown of the tree in rarer cases where the damage is less severe.

They also let their lower branches fall to the ground as they age. This natural pruning phenomenon prevents fire from being able to climb up the tree and burn the green needles higher up the tree.

Most coniferous trees die in forest fires and grow back from seeds. But some coniferous tree species seem to thrive in fire-prone environments. Fire makes the resin that coats their cones melt, releasing the seeds inside that have been dormant.

This groundbreaking strategy is the trademark of the Aleppo pine, which has adapted so well to fires that it uses them to prolong its life.

These unique features are examples of how trees have evolved to adapt to frequent fires. Thanks to trees' diverse range of adaptive responses to wildfires and their ability to regrow, Mediterranean natural areas often come back looking identical as before. 

But it's not all rosy—all too frequently in these same areas, fire stops the pine trees from reaching sexual maturity, and stumps and leaves die out over time. Trees may eventually disappear for good, giving way to heath or scrubland.

March 2012, forested region in Vaucluse, southern France. Our team of scientists, specialists in Mediterranean forests, measure how quickly the flames spread during a controlled burning exercise.

This technique, carried out by the French Government, consists of destroying vegetation that fire can use to spread in at-risk areas. Fire is allowed to spread in a predetermined direction, downhill and against the wind, and then put out by firefighters.