Fire, a key element in the ecological and evolutional process of the vegetation of the Mediterranean basin
Cristina G. Pedraz/DICYT Fire Ecology is the scientific discipline that studies the role of fire in organisms and ecosystems. Despite the fact that fire has a generally negative connotation, it is part of the ecosystem and there is evidence that it has occurred ever since the appearance of land plants millions of years ago in the Palaeozoic, and that it has therefore influenced their evolution. For instance, ecosystems prone to fire, such as those of the Mediterranean, are dominated by vegetation that is adapted to fire as a result of this long association.
The Functional Ecology Centre of the University of Coimbra, which is attached to the Faculty of Science and Technology, is working on this line of Fire Ecology research, to be precise the researcher Bruno Moreira. He affirms that it is “fascinating” trying to understand the strategies and mechanisms that plants use to survive in these ecosystems and the effect of fire on vegetation patterns.
Moreira has mainly concentrated on studying the role of fire in the ecology of the plants and ecosystems of the Mediterranean area. “Many species living in areas where fire is an important factor have acquired adaptive characteristics that allow them to survive in these ecosystems. For example, some species have developed very thick bark that allows them to resist fire, and others have the capacity to re-sprout after having been burnt by fire from organs protected from the heat”, he points out.
Likewise some characteristics are related to the persistence of the population. “Adult individuals are eliminated by fire, but the population persists by means of post-fire recruiting from seeds that have accumulated in cones (an ecological adaptation known as serotiny) or in the soil”, he explains.
Bruno Moreira has been working on this line of research for nine years. As a degree student he spent some time at the Environmental and Sustainability Institute of the European Commission in Italy as part of the INFOREST (Information and monitoring of the forest environment) project, where he began to take a closer look at the subject. Once he had graduated he was awarded a Leonardo da Vinci grant to work at the Mediterranean Environmental Studies Centre in Spain, where he took part in several projects and collaborated with various experts in the field of forest fires, ecology, plant conservation, and the restoring of Mediterranean ecosystems. The possibility later arose of studying a doctorate in Fire Ecology with Doctor Juli Pausas of the Desertification Research Centre of the Higher Council for Scientific Research (Consejo Superior de Investigaciones Científicas, CSIC) in Spain, with whom he is still collaborating today.
During this time he has studied in depth the mechanisms that allow plants to survive fire, the factors affecting plants' capacity to re-sprout. and the stimulation of germination by heat or smoke associated with fire.
In order to carry out these studies varied techniques and methodological approaches have been used, mainly experimental work in the field and in the laboratory to measure plant characteristics associated with re-sprouting, post-fire recruiting, fire itself, or population genetics.
The role of smoke in seedling growth
The results obtained over the years from this line of research support the fact that fire plays a key role in the ecological and evolutional process of the Mediterranean basin. In articles published in journals such as PLOS ONE, Annals of Botany, and the Journal of Vegetation Science researchers have shown that both the heat and the smoke that are associated with fire stimulate the germination of several species from the Mediterranean basin. In some species initial seedling growth is also stimulated by the chemical compounds present in smoke.
On the other hand, in the context of the hypothesis that in ecosystems prone to fire natural selection favours characteristics that increase the ignition capacity, evidence has been found that a germinating species (Ulex parviflorus) that is present in areas with recurrent fires “has greater flammability than populations of the same species existing in areas where recruiting does not depend on fire”, Moreira explains.
The future objective is to study and understand the effect of fire on the structure of communities in ecosystems prone to fire. “Establishing the factors that determine the richness of species and how they do so, understanding on which species fire has a positive effect and on which it has a negative effect and which characteristics are associated with these species, and studying coexistence within the community in greater depth, i.e. why certain associations occur between some species and not others, will be some of the next steps”, the researcher concludes.
Moreira B., Castellanos M.C., Pausas J.G. (2014). “Genetic component of flammability variation in a Mediterranean shrub”. Molecular Ecology, 23 (5): 1213-1223
Tormo, J., Moreira B., y Pausas, J. G. (2014). “Field evidence of smoke-stimulated seedling emergence and establishment in Mediterranean Basin flora”. Journal of Vegetation Science, 25 (3): 771-777