Effetti della dimensione delle buche sulla rinnovazione naturale in rimboschimenti di pino nero

Gap size effects on tree regeneration in afforestations of Black pine (Pinus nigra Arn.). The authors deal with the problem of the re-naturalization of afforestations of Black pine in the Apennines (Central Italy). Gap-cutting of two different sizes (the gap diameter/stand height ratios were respectively 0.75 and 1.0) on age classes stands (respectively 50 and 90 years old) have been carried out. The results of the dynamics of the tree regeneration established in the gaps 7 years after the beginning of the experiment are given. The Black pine represents the best regenerated tree species and its presence is increasing. Some broadleaves, Pubescent oak (Quercus pubescens Willd.) and Holm oak (Quercus ilex L.) particularly, and Hop-hornbeam (Ostrya carpinifolia Scop.) and Manna-ash (Fraxinus ornus L.) on a subordinate way, are also present in the gaps. These results confirm that the gap-cutting system represents an effective instrument for the natural regeneration priming and a low impact environmental treatment which is particularly fit for the re-naturalization of the conifers’ monocultures. According to this experience the gaps’ optimal sizes are 150-250 m2. These gaps should be distributed appropriately in space and time.