Resprouting patterns after fire and response to stool cleaning of two coexisting Mediterranean oaks with contrasting leaf habits on two different sites

摘要

The extension of mixed evergreen (Quercus ilex) and winter deciduous (Quercus cerrioides) oak coppices is increasing in NE Spain as a consequence of large wildfires. The best alternative to manage these high-density and low production forests is their conversion into stored coppices (i.e. coppices with few stems per stool). However, in this process, functional differences arising from the contrasted leaf-habit of the two co-occurring oaks should be taken into account. In this study, we explore the resprouting patterns and the response to different intensities of stool cleaning and pruning of these co-occurring Mediterranean oak species in mixed extensive coppices which have appeared after large wildfires. According to our results, both species resprouted vigorously after fire in the different environmental conditions studied, with an important influence of the size of the stool. For a similar stool size, Q. cerrioides exhibited higher number of resprouts, height, basal diameter and crown cover, with specific differences increasing in high-quality sites. Cleaning of stools increased height and basal diameter growth, with low differences between the two cleaning intensities (i.e. one or three respmuts reserved per stool). Pruning did not modify height or diameter but enhanced crown expansion. As a consequence of cleaning, a new wave of basal resprouts appeared. The mean number of these new resprouts was higher in Q. ilex than in Q. cerrioides, while the height they reached increased with cleaning intensity. The reported benefits of cleaning on growth diminished earlier in Q. ilex in comparison with Q. cerrioides, probably due to the larger production of this new wave of basal resprouts in the former species. These results suggest that, despite the differences among evergreen and deciduous species, both oaks may operate successfully in a wide range of environmental conditions. In the two species, moderate cleaning (three reserved stems per stool) appears to be a more suitable practice than intense cleaning (one stem per stool), because these similar growth rates but moderate cleaning favours a lower development of new resprouts.