Rising From the Flames: How Plants Adapt to Forest Fires
Forest fires are raging infernos that burn everything in their path and turn push green forests into charred wastelands… or so it seems. However, to plants and trees that grow in areas where forest fires are frequent, fire is part of the cycle of life. In fact, plants have evolved to survive and thrive In fire thanks to many innovative adaptations.
Some trees have an adaptation called serotiny, which means that their seed-bearing cones are sealed shut by a thick layer of wax. These cones can only open during a fire because intense heat is needed to melt away their wax and release their seeds. Similarly, seeds from many plants around the world open only when they detect the chemical compounds present in smoke. Both these mechanisms ensure that the seeds will begin sprouting at exactly the right time. After a fire has burned away the other competing plants, newly sprouted seedlings will have all the sunlight and nutrients they need to grow.
There are many different stages of a forest fire. Most of the time, fires start on the ground. Fire can use low tree branches like a ladder to move all the way up to the tree’s crown. Crown fires are the most intense and deadly for a tree, so some trees like Ponderosa pine have developed a self-pruning mechanism to avoid them. They will lose their lower branches as they get taller, which helps protect their top branches and reduce the intensity of a forest fire. While these trees may look like goofy tufts on the end of long poles, they are well-equipped to survive!
Dead plant materials on the ground, like pine needles, for example, are the fuel that keeps a wildfire burning. If these needles catch fire easily, there will be forest fires often. This might seem like a bad situation for a tree, but it is actually an advantage! Since fires around these trees are frequent, the needles burn up almost as soon as they fall and they are never very much fuel on the ground to sustain a long fire. This means that the forest fires will stay small and won’t burn very long. A tree with thick enough bark and highly flammable needles can easily survive these short small fires.
You can test the powers of Serotiny for yourself!
If you live in an area where serotinous trees grow (ask your parents if there are any Lodgepole or Jack pines near you), you can easily test the powers of Serotiny.
Collect some cones from nearby trees and place them on a baking tray. Put the tray in the oven and heat it up to 300 Degrees Fahrenheit, Watch what happens as the cones get hotter. Once the cones have opened, ask an adult to help you remove them from the oven. When they have cooled, compare them to the unheated cones. What do you notice?
You can also watch the video below and see how it works!