Against all suspicion, trees work together in solidarity to protect themselves against dangers such as fires. Each species has a different technique developed and specialized over centuries and millennia to recover from these dangerous situations.
Just as human beings cannot afford to live in isolation, a tree cannot create an ecosystem and a forest on its own. Trees, just like us, need to create a "community" where each member, depending on the species and the age, has a specific function that allows them to buffer extreme heat and cold, produce humid air, and store water. In this "tree community", communication is necessary.
The key to their language is found in the roots, through which information is passed on about various dangers such as lack of water and nutrients or even the presence of a fire. Indeed, when there are fires or abnormal temperatures, information is sent to alert that something is wrong with the ecosystem. This data arrives very quickly through the hyphae, a network of ultra-fine filaments of fungi that are widely distributed within the ground.
When facing a fire alert, every type of tree and shrub within the community prepares to survive the fire. In the Mediterranean, for example, pyrophytes, tree species that manage to protect themselves from danger, have developed through the centuries. Many species of pine, oak, and holm oak are pyrophytes. When the top of the tree is burned, the oaks and holm oaks can produce new shoots from below. When there is a surface fire certain species of pines have a cork bark that serves as an insulator and can survive without a scar.
Other types of pines have other strategies to protect themselves, such as producing pine cones. They are not eaten but burst when they feel the fire and disperse their pine nuts so that, once extinguished, they can be reborn in clear, nutrient-rich soil. The sticky rockrose is another Mediterranean species with a curious protection strategy: this bush produces a resin in its leaves that makes them burn instantly. In this way, the fire does not affect the soil and, like the pine, it makes its fruits explode to spread the seeds and then germinate again.
For all these reasons, after a fire, it is not recommended that heavy machinery such as excavators enter the forests to clean the ashes, where once the area has been razed there are two alternatives, natural regeneration or reforestation. These vehicles could take away the seeds that the trees in the area have naturally replanted to revive them. Also, experts such as Miguel Ángel Hernández, coordinator of Ecologists in Action in Castilla-La Mancha, defend that the areas that have been left to regenerate themselves are in a better condition than those in which are interfered by human activities. Natural regeneration, combined with specific human actions, means that the area does not get worse and prevents problems such as erosion.
For this natural regeneration to take place, several factors must be taken into accounts, such as the speed of the fire or the species of the trees. If the fire is fast, the regeneration capacity of the area is high. On the other hand, if it is slow and the land is burned a lot, it can destroy all the trees and reduce their capacity to regenerate, depending on the species.
It takes approximately 100 years for a destroyed forest to fully recover, and there is a possibility that it will vanish forever. It could disappear, for example, if it catches fire again in a short time because trees such as pines take years to produce good seeds.
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