On s’emporten les llavors els rosegadors quan es talla el bosc cremat?

Abstract

After a fire, in southern Europe, the most common way to manage a burned forest is a salvage logging with heavy machinery and whole-tree harvesting, which eliminates almost all the biomass present in the ecosystem. There are also other methods less used such as nonintervention, which leaves the forest in the conditions in which it has remained after the disturbance. Another post-fire management provided by the Anifog project, of the University of Girona, is the treatment of good practices, using light machinery and stem-only harvesting, leaving woody debris in the form of piles in the area. To compare the efficacy of the three treatments in reference to the regeneration of the forest, an area near Blanes (Girona, Catalonia), burned in July 2016, was chosen, and the differences in the removal of acorns by rodents were studied because these seeds (if they were in the right conditions) could then germinate and thus help return the forest to its initial state. Ten plots were established and distributed to manage them differently for each treatment. Each forest management had 20 stations under shrub resprouts, and the treatment of good practices had also 20 stations under branch piles. The collection of 3 variables was carried out: rate of removal of acorns, distance from the acorn to the station and micro-habitat where the acorn was found, in two experiments (autumn 2017 and spring 2018). After treating the data statistically, it was found that in the last two groups of data mentioned, the methodology was not successful and, therefore, the results could not be representative due to lack of samples. On the other hand, regarding the rate of removal, the results were of more acorn removal in the case of the stations under the branch piles of the treatment of good practices, and significantly less in the conventional treatment. All in all, it could be said that the treatment of good practices and, specifically, the presence of branch piles is favourable for the removal of acorns by rodents and could have positive effects for a faster natural regeneration of the forest if the dispersal compensates predation. Aversely, conventional treatment seems to have a negative impact on the dispersion of seeds, they are removed more slowly; therefore, it could mean that it is not the best management option for rodents and their ecosystem services