European ash (Fraxinus excelsior L.) secondary woodlands in Italy: management systems and timber properties

Secondary forests have recently reached a notable importance in terms of extension, increasing the forest area in central Europe, and opening new questions about their management. In the Italian pre-Alpine region ash-lime and ash-sycamore forests cover more than 150.000 hectares. Usually these new forests occupy private lands abandoned after agricultural practices. These forests are generally left to natural evolution or managed as coppice for firewood production. To address possible uses of ash timber from secondary forests, we carried out a physical and mechanical characterization on logs from two study areas in north-eastern Italy. The timber characteristics of two ash stands, aged 37 and 60 years, have been obtained analysing 35 plant stems. We calculated wood density at 12% moisture content, wood basic density, radial and tangential shrinkage, the ratio between tangential and radial shrinkage and module of rupture and module of elasticity. Presence of black heart was estimated in the transverse area on each tested sample. Results show that timber obtained from the two studied stands present good mechanic and physic properties suitable for saw-timber and veneer uses. The high presences of black heart, especially in the older stand, modify wood physical properties and undervalue strongly the timber for aesthetical applications. A different forestry approach has been applied to obtain trunks of commercial dimension in shorter rotation (< 70 years), reducing in this way the incidence of black heart. Single tree oriented silviculture could be an interesting management able to increase diametric growth and to produce trunks of 60 cm in less of 70 years, decreasing the presence of black heart in the stems.