We are used to seeing images of bare mountains after devastating fires that take place every summer. What do plants do to overcome this disturbance?
Forest fires are a problem today, and they have been intensifying with human activity. However, fire is also a natural disturbance in Mediterranean environments, which is why many of the plant species have adapted to it and are even favored by it. These plants are called pyrophytes, and they have managed in various ways to recover after fires. Many species are capable of regrowth through offshoots that are generated from the body of the burned individual. They are called 'regrowth' plants and among them are the strawberry tree (Arbutus unedo), The oak (Quercus ilex), the mastic (Pistacia lentiscus) and kermes oak (Quercus coccifera).
Other species, such as rockrose (Cistus sp), they produce many small seeds that remain buried in the ground and that are able to withstand high temperatures. After the fire, the seeds find an ideal moment to germinate, since open spaces are generated with lots of light, without competition with other plants and with new mineral resources that come from the ashes. This strategy is called 'germinadora' and for rockrose, as well as for many typical aromatic species of the Mediterranean forest such as rosemary (Rosmarinus officinalis), fire is an opportunity to occupy areas where they were not before.
Natural weapons to survive
Other species such as the resin pine (Pinus pinaster) and Aleppo pine (Pinus halepensis), they develop cones that remain closed for several years until the fire produces the opening and the dispersion of their seeds. This strategy is called 'serotinia' and, in the case of Mediterranean pines, cones can also open in the absence of fire, unlike other tree species in South Africa, Australia and California, which depend exclusively on fire to be able to disperse their seeds.
In spite of everything, the regeneration of vegetation after a fire is not an easy task. After the fire, the soil is bare and is much more vulnerable to erosion. In addition, although the ashes release nutrients that were stored in the plants, there is also a strong loss of organic matter. For this reason, some human actions aimed at restoration after fires begin by protecting the soil, for example by placing barriers of logs or straw shavings to prevent erosion.
To be able to properly manage burned forests, it is essential to understand the ecology and the mechanisms developed by plants to adapt to fire.