Management of burnt areas and rabbits
The occurrence of forest fires is a natural phenomenon in Mediterranean ecosystems. In recent decades the frequency and spread of fires have become prominent factors in the economics, social impact and conservation of biodiversity. The abandonment of traditional agricultural and grazing activities in forests has contributed in particular to the current pattern of forest fires. After a fire it is standard practice to remove any timber from large burnt trees with potential commercial value, leaving the burnt branches in situ along with other burnt vegetation of no commercial value, post-fire activities that are normally subsidized by the government. However, it is unknown if leaving burnt branches in situ influences the management of post-fire forest productivity and biodiversity conservation.
To know the effect of wild-fires and post-fire forest treatments on biodiversity, we undertook a specific study, with the support from Diputació de Barcelona, on the evolution of the rabbit population in different areas of the Sant Llorenç del Munt i l’Obac natural park, which in August 2003 was hit by a forest fire that burnt some 4,600 hectares. The basic objective was to study how forest fires and post-fire forest management affected the abundance and recovery of rabbit populations. To do so, during 2006-2008 we looked at 40 different plots of land to which different post-fire forest management techniques had been applied: a) natural areas not burnt, b) burnt areas where burnt branches were left in situ, c) burnt areas where all burnt wood was removed (experimental plots), and d) areas of low vegetation cover before the fire. The removal of burnt branches in experimental plots was possible thanks to the collaboration of several volunteer groups and the support from Obra Social “La Caixa”.
Results revealed that rabbit populations recovered faster and reached high abundances in the burnt areas tha in unburnt areas. Additionally, in burnt areas where the burnt branches were removed, rabbit populations grew faster than in plots where the burnt branches were left on the ground. Finally, close analysis taking into account the different layers of vegetation and burnt wood showed a strong negative correlation between the amount of burnt wood left on a plot and rabbit abundance and, in contrast, a positive correlation in the case of uncovered soil and the existence of herbs and grasses. The reasons for these results lie, firstly, in the fact that fires ‘open up the landscape’, and that the early stages of regeneration after a fire encourage the growth of herbs and grasses of high nutritional value for rabbits, so the species can reproduce at an adequate rate. Secondly, burnt branches left in situ are likely to prevent not only the movement and actions of rabbits but also the growth of these plants of high nutritional value.
Therefore, removing burnt wood left by forest fires would be contribute to the recovery of rabbit populations, essential for the conservation of highly endangered species and the future of Mediterranean biodiversity. Furthermore, the application of this technique paves the way for the use of controlled burning as a tool for the improvement and recovery of rabbit populations.
A27.- ROLLAN, A. & REAL, J. 2010. Effect of wildfires and post-fire forest treatments on rabbit abundance. European Journal of Wildlife Research, 57 (2): 201-209. doi: 10.1007/s10344-010-0412-y. pdf
E22.- ROLLAN, A., TINTÓ, A. & REAL, J. 2005. Avaluació de l’Abundància relativa de conill (Oryctolagus cuniculus) i el tractament forestal post-incendi. VI Trobada d’Estudiosos de Sant Llorenç del Munt i l’Obac. Sant Llorenç Savall (Barcelona). pdf
- Improving post-fire forest management to promote biodiversity in the Mediterranean ecosystems (4/05/2011): More