RESPONSE OF THE SEED BANK TO THE POST-FIRE RECOVERY OF A MEDITERRANEAN WOODLAND ECOSYSTEM

In many Mediterranean countries, often regional rules do not admit the pastoral use of burned woodlands for years. This means that, without the fuel consumption by grazing animals, the dynamic of the green coverage succession after a fire is destined to reach the stage of a shrub land, dominated by Cistus spp., which maintains high the risk level of fire occurrence, also slowing down the times of reaching the wood climax. The simulation of a post-fire recovery of a Mediterranean Quercus spp. wood was carried out during five years, introducing traditional pasture species (subclovers, burr medic and annual ryegrass), controlling the fuel biomass by a low-pressure animal grazing (dairy sheep) and protecting the native juvenile plants of Quercus spp. with fences. Data on the seed bank components dynamic and floristic composition were collected. The variation of soil seed bank and floristic composition at different levels of environmental variables like pH, altitude, total nitrogen, exposure and slope was observed. Results show that: a) the introduced pasture mixture plays a competitive role against the native grasses and shrubs and other colonizing unpalatable species; b) increases the N amount in the soil c) improves the palatability of the pasture and the biomass removal by animals, helping in reducing the fire risk. In the post-fire recovery of Mediterranean woodlands the sylvopastoral approach could be a useful tool to facilitate the rehabilitation of a disturbed Mediterranean ecosystem, mainly in those marginal areas where extensive farming systems are widely diffused and characterize their economy