DUGi

Calibratge d’un mètode d’estima de l’abundància de Cicadidae i fenologia d’emergència de Cicada orni a boscos cremats i no cremats

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@11235

Cicadidae or Cicadas, like the majority of insects, are mostly unknown for most people including their life history and ecology such as the nymph emergence. Moreover the effect of fire to these particular animals is also clearly unknown so far. We studied a population of Cicadas based on the nymph emergence among burned (one and two years after the fire) an unburned Aleppo pine forests. We used replicated plots to collect nymph exuviae (the abandoned exosqueleton after the last moult) once a weed across the whole emerging period (June to September). Nymphs collected were used to measure the abundance phenology of emerging nymphs, and the body size and sex ratio of cicadas. We used absolute density data from our plots to validate a new method of measuring relative abundance of emerging cicadas based on transects. We found significant differences in the nymph phenology of cicadas between burned and unburned habitats, probably related to the vegetation cover and sunlight. Interestingly, we found an advancement of the nymph phenology in burned habitats that seems to be connected to the lack of vegetation cover on this area and the fast heating of the ground. Despite these results, we didn’t find differences in size and sex ratio between burned and unburned habitats, maybe related to the sample size that was available. Nevertheless, we should consider do a further investigation on the size and sex ratio of cicadas to get a trustworthy result about their variation among burned and unburned areas. To conclude, we found that the abundance estimates using the new transect method was highly related to our absolute density measures found in plots. This study has provided me a new knowledge on cicadas and the role that they have in their ecosystem. Moreover, this study shows the alteration that the fire represents for these animals. Furthermore, knowing these significant alterations to the emergence phenology could be useful to further studies to assess the consequences in the ecosystem