FABIO LOMBARDI (*) (°)-GHERARDO CHIRICI (*)-MARCO MARCHETTI (*) ROBERTO TOGNETTI (*)-BRUNO LASSERRE (*)-PIERMARIA CORONA (**) ANNA BARBATI (**)-BARBARA FERRARI (**)-SILVIA DI PAOLO (**) DIEGO GIULIARELLI (**)-FRANCO MASON (***)

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Sasso Fratino Nature Reserve (National Park of Casentino Forests, northern Apennines) is a quite rare example of natural Apennine forest. The Reserve was established in 1959, aiming to protect a forest, although not a virgin one, low-intensively disturbed in the past by comparison with other neighbouring stands. Causes of such a low disturbance are the very limited accessibility of the area due to the very steep slopes characterising the site morphology, as well as historical features. The forest is a pure beech stand from 1250 m a.s.l. upwards, below this altitude is a mixed beech and silver fir forest. The study focuses on the understanding of the processes driving the evolution of the forest in the absence of human activities. To achieve this goal, 9 permanent, long-term research plots were established at different altitudes, in order to investigate on forest dynamics and regeneration processes. Simplified (single-layer) stand structures are more frequent where canopy gaps are absent. Two-layered structures are the result of the occurrence of canopy gaps, which allow the settlement, and subsequently the establishment, of a lower regeneration layer. Where the gap dimensions allow canopy closure, this kind of structure persists. When the gaps are quite large, the regeneration layer reaches the top layer and the structure stand tends, once more, toward a single-layer. Multilayered structures are extremely rare at plot level and become evident only at a wider scale. Our surveys indicate also a high variability of tree diameter distribution patterns in the forest stands. Such variability could be strictly related to the heterogeneity of site characteristics as well as to the effects of disturbance factors (both natural and anthropic). Concerning altitude, we observed an increase both of site index (dominant height) and species diversity in the regeneration layer, moving from higher (1500 m) to lower (900 m) altitudes. As a whole, our observations show that the dynamics of forest vegetation in the reserve is mostly affected by the interruption of tree canopy continuity. This implies substantial local variations of PAR in space and in time, which determine favourable ecological conditions for: (a) survival and growth of beech seedlings, or release of advanced beech regeneration; and (b) release of advanced silver fir regeneration (fir, more shade tolerant than beech, regenerates mainly in locations and conditions where the broadleaf saplings cannot survive for lack of light). The knowledge of the mechanisms of vegetation dynamics in the Reserve can be used to form the basis of close-to-nature silvicultural choices in similar stands in order to increase functionality and stability. Periodical monitoring of RNI will allow the investigation of the evolutionary trends of the forest stands

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An old-growth beech forest stand with silver fir within the strict forest reserve of Sasso Fratino has been examined with the following aims: to characterize forest stand on the basis of classic forest parameters and to assess forest stand structure by means of spatial functions; to provide genetic dating of the beech population. Total census of size and position of living trees and deadwood was performed on a 9200 m 2 permanent plot. Vertical distribution of crowns in the stand was assessed using the TSTRAT function, horizontal stand structure using spatial point pattern analysis. Genetic dating was performed on a sample of beech trees. DNA was isolated and each individual was genotyped at four chloroplast microsatellite loci. Microsatellite profiles were compared with the profiles of control DNA of known haplotypes. Results show a multi-strata vertical structure, a horizontal structure characterized by small gaps (5160 m 2 ) where silver fir regeneration sets in. Deadwood is present with all the decay classes and with relatively high volumes. Genetic dating ascribes the Sasso Fratino beech stand to the ancestral haplotype 2: this population can therefore be considered a hot spot of haplotype diversity of the glacial refugia present in central Italy.

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PremessaSecondo 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 colturali. 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...

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