Premessa Secondo l'Inventario Forestale della Toscana (Hof mann et al. 1998), i boschi a prevalenza di pino nero occupano 20496 ettari, di cui 7500 sono cedui conife rati e fustaie miste: tali dati sono in linea con quelli del recente Inventario Nazionale (INFC 2007) che at tribuisce ai rimboschimenti della conifera una super ficie pari a 18427 ettari, di cui 10117 sono rappresen tati da boschi puri. La maggior parte di questi soprassuoli hanno rice vuto scarse e spesso occasionali cure

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... i. La mancanza di diradamenti in molti casi ha portato ad uno stato di elevata fragilità che frequentemente de termina crolli strutturali più o meno intensi ed estesi, rischiando di compromettere le azioni positive degli impianti in termini di difesa idrogeologica (Amorini Forest@ 7: 73-83 (2010) 73 Abstract: Effects of thinning intensities in experimental plots of Black European pine in "Foreste Casentinesi, Monte Falterona and Campigna National Park" (Tosco-Romagnolo Apennine, Italy), eight years after the felling. Different thinning intensities were compared in a 50-years-old plantation of Pinus nigra sp. located in the "Foreste Ca sentinesi Monte Falterona e Campigna" National Park (northern Apennine -Italy). Six experimental square plots (900 m 2 ) were set up for comparison of two thinning intensities: heavy thinning (F: approximately 30% of basal area removed), light thinning (d: approximately 15% of basal area removed) and control (Co). The comparison concerned: (1) the periodic increment of the trees in terms of volume (Ipv), average dbh (Ipd), height (Iph) and the variation of height/diameter ratio (S) in time; (2) forest canopy cover, indirectly expres sed in term of relative irradiance (I.R.). Eight years after the felling, the results highlight that F thinning: (a) increases the homogeneity of timber, as the stand volume is concentrated in dominant trees; (b) favours tree diameter increment: Ipd values increase significantly according to the thinning intensity; (c) reduces tree height increment (lower values of Iph were recorded in the F plots); (d) promotes stand stability: lower value of S are highlighted in F plots, and no significant increase of this parameter in time has been recorded. As re gards canopy cover, a significant negative correlation was recorded between stand basal area after the thin ning and I.R. at ground level. After harvesting, a significant difference in terms of average I.R. between thin ning intensities (F, d and Co) was also recorded: nowadays, significant differences of average I.R. are obser ved between Co and d, whereas F shows intermediate values: the canopy gap originated from the felling has been quickly filled. Our results highlight the growth potential of Black European pine in the studied area; however, only heavy thinning shows interesting results in terms of both tree growth and stand stability. Citation: Bianchi L, Paci M, Bresciani A, 2010. Effetti del diradamento in parcelle sperimentali di pino nero in Casentino (AR): risultati a otto anni dall'intervento. Forest@ 7: 73-83 [online: 2010-04-01] URL: http://www.sisef.it/forest@/.