Recovery of cork forests and enhancement of by-products

Abstract

Cork oak (Quercus suber L.) is a tree species native to the western Mediterranean Basin (EUFORGEN 2019). Cork oak forests are human-shaped ecosystems that have to be managed to be preserved in a long-term perspective. Cork oak stands range from closed forests to open woodlands, provide high ecosystem services, mainly through cork production, support high biodiversity and provide carbon storage and water regulation services. Due to their important ecological role, these ecosystems are listed in the European Habitats Directive (Habitat 9330: Quercus suber forests, EEC, 1992). In the last years, especially in Italy, cork oak stands are undergoing a relevant regression due to the decline of traditional management. The most extensive cork oak forests occur in Sardinia, followed by Sicily, Tuscany and Calabria. In Sicily, this tree covers about 19,000 ha (about 7% of total regional forest cover), from sea level up to 1,000 m a.s.l (Camerano et al. 2011). Also in this region, the abandonment of traditional management and recurrent wildfires has caused a progressive decline of cork oak forests and widespread degraded conditions. In this work, we analysed the recovery of a cork oak forest through the improvement of management in a study area where cork oak is mixed with stone pine (Pinus pinea L.). To improve the vitality of cork oak and increase cork production, the thinning of the pine stand was carried out. The silvicultural treatments were carried out without a total removal of pine trees and uncovering of the soil but selecting the pine trees that effectively hindered the cork tree. In the future, the response of the forest system will be evaluated in terms of natural regeneration and other cautious, continuous and capillary interventions may be proceeded. After felling, trees were processed in 2-meter length assortments while thin material, tree tops and branches were chipped and left on the ground. We collected data on: 1) site conditions (topography, soil conditions and understory vegetation), 2) stand characteristics (adult tree layer, species composition, density, structure) and 3) time for felling and logging the stone pine. We also evaluated the quantity of the wood material obtained. This study provides technical recommendations that can support sustainable management and restoration efforts in Mediterranean cork oak landscapes. This type of management in addition to produce cork will allow high level of biodiversity and socio-economic benefits.