Short-term effects of prescribed fire and soil mulching with fern on natural regeneration of Quercus frainetto L

Key message: In Mediterranean oak stands prescribed burning increases acorn emergence and plant survival, while post-fire soil mulching with fern does not significantly enhance the initial recruitment of plants. Abstract: To avoid the negative impacts of wildfire, prescribed fire is applied in several environments, often with post-fire soil mulching, to control wildfire hazard and erosion in burned areas. However, uncertainties remain about impacts of these forest management techniques on post-fire regeneration, especially for some forest species, such as oak, which is predominant in Mediterranean fire-prone areas. This study evaluates the effects of prescribed fire and post-fire soil mulching with fern on initial recruitment of an oak forest of Southern Italy. Acorn emergence and seedling survival as well as some important plant and root biometric characteristics (height, diameter, and dry weight) have been monitored in plots burned by prescribed fire with or without post-fire treatment with fern. The acorn rain among the experimental conditions was not statistically different, whereas the prescribed fire significantly increased acorn emergence compared to the unburned area. About 30% of acorns germinated, of which more than 70% survived. Soil mulching with fern did not significantly increase acorn emergence (35%) and plant survival (85%) compared to the burned and untreated sites, presumably due to the shadowing effect of the cut fern, which reduces the light availability for juvenile plants. However, this post-fire treatment significantly enhanced plant height (+ 44%) and root mass (+ 30%) but not its diameter (+ 6%) and root length (+ 1%). These contrasting effects in part support the initial hypothesis that soil mulching may be synergistic with the prescribed fire. Overall, the knowledge of the beneficial influences of prescribed fire and post-fire treatments on oak recruitment, thanks to the fire-tolerance character of this forest species, is useful to develop sustainable management plans for the delicate forest ecosystems of the semi-arid Mediterranean environment.