http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 23 May 2013 11:41:45 GMT 2013-05-23T11:41:45Z http://hdl.handle.net/2067/1045 Title: Analisi delle variazioni di produttività di tre nuclei di faggeta aventi carattere di vetustà Authors: Alessandrini, Alfredo Abstract: Lo studio della produttività delle cenosi forestali riveste una notevole importanza al fine di comprendere come le recenti variazioni climatiche agiscano sui processi di accrescimento dei boschi. Negli ultimi decenni si sta registrando un aumento delle temperature, il cui effetto sulla crescita dei boschi è ampiamente dibattuto. Nel bacino del mediterraneo, molti autori hanno riportato come, soprattutto per le cenosi forestali montane, si stia assistendo ad una riduzione della produttività, e in taluni casi ad un arretramento del limite superiore della vegetazione. Tali processi dipendono dall'aumento delle temperature che causano un incremento dell'aridità, il fattore limitante la produttività delle cenosi forestali. In questo contesto il presente studio ha avuto come obiettivo l'analisi della produttività di tre faggete vetuste dell'Appennino Centrale. Per stimare la produttività, si è utilizzato l'incremento di area basimetrica (BAI), che rispetto all'incremento di diametro, presenta il vantaggio di essere meno dipendente dalle dimensioni/età,rispetto alle ampiezze anulari.Per lo studio delle variabili climatiche, si è utilizzato un dataset di punti griglia di temperature e precipitazioni, che ha permesso di ricavare delle cronologie di tali parametri. L'aridità è stata calcolata mediante l'utilizzo di due indici: Z-INDEX - Palmer Moisture Anomaly Index e PDSI - Palmer Drought Severity Index. Inoltre sono stati utilizzati degli indici derivati da immagini satellitari: NDVI - Normalized difference vegetation index e FAPAR - Fraction of Absorbed Photosynthetically Active Radiation. I risultati ottenuti, hanno permesso di chiarire quali sono i segnali climatici che regolano le variazioni di alta e bassa frequenza della produttività delle cenosi forestali, permettendo in questo modo di comprendere meglio quali possono essere le consegunze delle variazioni climatiche sulla loro produttività.; Aim: Understand how the recent climatic changes are impacting the basal area increment (an indicator of forest productivity) of beech woods in Italy. In recent decades there has been an increase in temperature; the effects on forest growth is widely debated, especially in Mediterranean areas, where some authors described a reduction in stand productivity in consequence of increasing drought (the factor limiting woods productivity). Materials and methods: Productivity of old-growth beech forests in the Mediterranean Basin was measured by average stem basal area increment (BAI) of dominant trees at three mountain sites in the Italian Apennines. Basal area increment (BAI) was used to estimate productivity. A dataset of gridded temperatures and precipitation series was used for the study of climatic factors controlling productivity. Drought at the two sites was quantified by the self-calibrated Palmer Moisture Anomaly Index (Z-index), and by the self-calibrating Palmer Drought Severity Index (PDSI) for summer (June through August) and the growing season (May through September). Indices derived from satellite images were also compared to productivity data: NDVI,Normalized difference vegetation index, and FAPAR, Fraction of Absorbed Photosynthetically Active Radiation. Results: The results obtained helped to clarify the climatic signals that regulate changes in beech woods productivity. Dendroclimatic analyses revealed a moisture limitation in beech BAI at the interannual (water availability measured by Z-index) and decadal timescales (water availability measured by PDSI). This impact was clearly detected by FAPAR, reconciling the observed BAI with remote sensing data. Conclusion: These findings have implications for modelling tree growth at the landscape level in relation to forest management options and carbon cycling estimates,especially with regard to the impact of climate variability. Description: Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale Wed, 25 Feb 2009 23:00:00 GMT http://hdl.handle.net/2067/1045 2009-02-25T23:00:00Z http://hdl.handle.net/2067/1355 Title: Alla scoperta di una foresta vetusta: la faggeta di Soriano nel Cimino - Il sentiero Natura - Authors: Alessandrini, Alfredo; Blasi, Silvia; Di Filippo, Alfredo; Piovesan, Gianluca; Ziaco, Emanuele Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2067/1355 2007-12-31T23:00:00Z http://hdl.handle.net/2067/1627 Title: Structural patterns, growth processes, carbon stocks in an Italian network of old-growth beech forests Authors: Piovesan, Gianluca; Alessandrini, Alfredo; Baliva, Michele; Chiti, Tommaso; D'andrea, Ettore; De Cinti, Bruno; Di Filippo, Alfredo; Hermanin, Luigi; Lauteri, Marco; Scarascia Mugnozza, Giuseppe; Schirone, Bartolomeo; Ziaco, Emanuele; Matteucci, Giorgio Abstract: In the framework of the Project of National Interest (PRIN) “Climate change and forests - Dendroecological and ecophysiological responses, productivity and carbon balance on the Italian network of old-growth beech forests”, 9 old beech (Fagus sylvatica L.) forests were sampled in the eastern Alps and in the central Apennines to assess: i) the degree of ‘old-growthness’ on a structural and dendroecological basis; ii) the carbon (C) stocks in the different ecosystem compartments; iii) some ecophysiological traits using stable isotopes. Live and dead tree structure, soil features and C stocks were examined in some among the oldest and less disturbed beech forests in Italy. Furthermore, leaves, litter and wood cores were sampled for concurrent dendroecological, nutrient and stable isotope analysis, to study age structure, disturbance history and medium- and long-term response to climate and ecophysiological traits. In all sampled stands, values of basal area, volume and large trees density reached or exceeded control values reported for European and North American old-growth forests, while total amount of deadwood was generally low, except in two sites. Diameter distribution showed a remarkable differentiation from bimodal to ‘rotated-sigmoid’ curve. In accordance with structural analyses, disturbance chronologies revealed the importance of frequent low-to-moderate events in generating a fine-scale structure, confirming previous results on beech forests. Different degrees of ‘old-growthness’ were identified for Alpine and Apennine beech stands through the ‘structural-based approach’, which proved to be a valid tool for old-growth forests detection. Preliminary results on carbon stocks on a subset of sites indicate that these old-growth forests are relevant carbon reservoirs, with 192-268 MgC ha-1 of total biomass (67-73% aboveground; 27-33% belowground, 4 stands) and 7-21 MgC ha-1 of deadwood. In these stands, also forest floor (excluding deadwood) and soils are stores of relevant amount of carbon (5-9 MgC ha-1 litter layer, 4 stands; 168-420 MgC ha-1 mineral soil, 3 stands). Finally, carbon isotope discrimination (Δ) analysis, a proxy of wateruse efficiency, was applied on tree-ring cores from a subset of sites. The perspectives of this technique for a retrospective ecophysiological interpretation of climate-change impact on old-growth forests were described. Preliminary results obtained within this PRIN project indicate that the reported ecological indicators can be used to produce a description of forest structures and processes driving stand dynamics (‘structural-based approach’). Furthermore, the use of multiple sampling and research techniques and the integration of research groups with complementary expertise can foster deeper understanding of the ecology and dynamics of old-growth forests. Description: L'articolo è disponibile sul sito dell'editore http://www.aisf.it/ Thu, 31 Dec 2009 23:00:00 GMT http://hdl.handle.net/2067/1627 2009-12-31T23:00:00Z