Living after the fire
Living after the fire
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 nowadays, and have intensified 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 resprouting by shoots that are generated from the body of the burned individual. They are called 'rebrowing' plants and among them are the strawberry tree (Arbutus unedo), the holm oak (Quercus ilex), the mastic (Pistacia lentiscus) and the kermes oak (Quercus coccifera).
Other species, such as cistus (Cistus sp), produce many small seeds that are buried in the ground and are able to withstand high temperatures. After the fire, the seeds find an ideal time to germinate, since they generate open spaces with lots of light, without competition with other plants and with new mineral resources that come from the ashes. This strategy is called 'germinating' and for the rockroses, as for many aromatic species typical of the Mediterranean forest such as rosemary (Rosmarinus officinalis), fire is an opportunity to occupy areas where they were previously not.
Natural weapons to survive
Other species, such as pine resin (Pinus pinaster) and Aleppo pine (Pinus halepensis), develop pineapples that remain closed for several years until the fire produces the opening and dispersion of their seeds. This strategy is called 'serotinia' and, in the case of Mediterranean pines, pineapples can also be opened in the absence of fires, unlike other tree species in South Africa, Australia and California, which depend exclusively on fire 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 left bare and is much more vulnerable to erosion. In addition, although nutrients are released from the ashes stored in the plants, there is also a strong loss of organic matter. For this reason, some human actions aimed at the restoration after the fires begin by protecting the soil, for example by placing barriers of logs or straw chips to prevent erosion.
In short, fire is a very common disturbance in Mediterranean forests and species have managed to adapt and even benefit from it. After a fire there is a very important loss of plants, but many are able to recover and also create a space with new environmental conditions to which species that were not present in the burned community can be incorporated. Finally, in order to be able to carry out an adequate management of the burned forests it is essential to understand the ecology and the mechanisms developed by the plants to adapt to fire, an element with which we necessarily live together year after year.
