Estudi de les diferències de microhàbitat i de la vulnerabilitat a la depredació visual de tibicina quadrisignata en boscos cremats i no cremats

Abstract

Tibicina quadrisignata is a species of the family Cicadidae which is distributed along the south of Europe (populations have been described in France, Catalunya and Portugal) that inhabits in arboreal and high thickets zones. Even though it is a common group, the Cicadidae haven’t been studied deeply and the effects that disturbances could cause on their habitat are unknown. Wildfires cause a great destruction of the habitat in which these species are found, and it can affect in different ways their survival. Specifically, this project aims to detect the possible variations of the microhabitat where Tibicina quadrisignata is found after a wildfire, and how the visual depredation is affected after this disturbance destroys partially or totally the natural shelter that represents the foliage of the vegetation. The team of the research project ANIFOG of the University of Girona recollected data of the microhabitat where the individuals where found in order to analyze the differences between burned and unburned zones by the wildfire of the Alt Empordà during the summer of 2012. In order to analyze the visual detection of the predators, a test was done to volunteers who had to discover the species in photographs of the specimens in their microhabitat and in both zones. This test increases the sample size of the test used by G. Banchs 2015 within her TFG. Significant differences have been found in the support diameter, which was higher in burned forests. Furthermore, differences between the height in which specimens were found were also significant, and appeared to be higher in the unburned zone. On the other hand, clear differences weren’t found between the detection of T. Quadrisignata. Individuals of the unburned zone appeared to have a the same percentage of detection, which is contradictory to what initially would be expected. This fact can be explained due to the dark color that T. quadrisignata has, which would grant them a mimetisation vantage in burned zones. The blackening of the bark of the vegetation brings as a consequence the confusion of the observer, who acts as a predator, of the specimen with the support where it is on. The increment of the diameter would work as a vantage, because it would increase the surface where the individual can mimetize. This results show that the effect of wildfire gives Tibicina quadrisignata a vantage when it has to visually hide from the predators, which compensates the loss the shelter that provides the foliage