Efectos del fuego sobre hormigas y otros artrópodos: un estudio a diferentes escalas

Zusammenfassung

The effects of fire on ants and other arthropods: a study at different depths Forest fires are one of the most frequent disturbances in Mediterranean environments. They greatly alter forest ecosystems, modifying the structure and composition of plant communities which consequently affects the structure and composition of the animal communities that inhabit them. The general objective of this Doctoral Thesis is to investigate the short-, medium- and long-term response three groups of arthropods have to fire in coniferous systems in Mediterranean environments of the Iberian Peninsula. We studied the structure and composition of the communities of ants, bees and spiders affected by fire from a taxonomic and functional point of view. We also measured how fire affects the hierarchy of dominance in ant communities. For this purpose, field sampling was carried out using pitfall traps, Moericke traps and baits in pine forests of the Iberian Peninsula affected by forest fires that occurred varying periods of time. Fire had a more pronounced effect on the communities of ants than in did on those of bees and spiders. The taxonomic response of ants (abundance, richness and diversity) varied highly. These variables decreased in the short-term in one case, recovered in the short-term in another case, and they even increased, independently of the time elapsed after the fire. At the functional level, the ant communities in burned areas are predominantly composed of thermophilic and subordinate species, and also of dominant species in more open habitats. In unburned areas, however, the species tend to be less thermophilic and are associated with more developed vegetation, especially the tree layer and tall shrubs. Therefore, fire may act as a niche filtering mechanism, with a long-term effect on some functional traits and a short-term effect on other ones. In conclusion, fire alters arthropod communities at the taxonomic and functional level, especially in ants. Taxonomic alterations are variable and depend more on the local scale (the recovery of the vegetation and the types of ant community present before the fire), while functional alterations are longer-term and more predictable.