1,721,159 research outputs found
Cambiamenti climatici e dinamica di popolazione al limite superiore del bosco: importanza delle ricerche di lungo termine
No full textLe fragili fondamenta della selvicoltura sistemica
No full textAn analysis is presented of the ecological basis of the so-called “selvicoltura sistemica” (systemic silviculture). Systemic silviculture implies an “a-structured forest”: the meaning of this particular condition is discussed in the paper, exploring the different possible interpreta- tions and thus demonstrating that an “a-structured” forest can not be observed in nature. The silvicultural method proposed therefore seems to have a fragile ecological basis moving it away from a close-to-nature fo- rest management approach, which is currently believed to be the most promising one for achieving forests that provide multiple goods and services
Analysis of the axial gradient of water potential in the main leaf venation of Fraxinus excelsior and Sorbus aucuparia
No full textL'impiego dei dati assestamentali per la stima dello stock di carbonio ai fini delle richieste poste dal protocollo di Kyoto
No full textParties included in Annex I of the Kyoto Protocol, like Italy, may choose to elect Forest Management as additional human-induced activity to attain the goals of reduction of greenhouse gas emissions. In Italy the majority of areas subjected to forest plans satisfy the definition of Forest Management proposed by the Marakesh Accords. However, the data commonly available from forest compartments cannot be directly used to estimate the total aboveground biomass by allometric equations because the data are not spatially (data differ among compartments) or temporally (data sampled in different years) uniform. This study proposes a methodology for using such non-uniform data, which has been tested on a dataset of forest compartments provided by the Veneto Region (NE Italy). A series of specific diameter distributions was associated to each forest compartment by applying cluster analysis and discriminant analysis. The Bootstrap procedure was applied to update the available data, referring them to the same year. The results satisfied the requirements of the "Good Practice Guidance for Land Use, Land Use Change and Forestry " of The Intergovernmental Panel on Climate Change since the uncertainties were quantified. After the analysis, forest compartment data were suitable for application of allometric equations, without need for further extensive sampling
Modelling stomatal uptake of ozone: data requirements and applicability of CONECOFOR permanent monitoring plots in Italy
No full textIt is accepted that ozone (O3) effects on vegetation depend mostly on the amount of O3 uptake rather than on exposure. As direct measurement of uptake is unfeasible under most forest conditions, modelling is needed. There are different modelling approaches (e.g. diagnostic and prognostic models) which follow the electric resistance analogue principle. Unfortunately, these models are data intensive and implementation can be difficult in sites which are not designed for canopy-atmosphere flux studies. The paper provides an overview on modelling approaches, identifies data requirements and evaluates the actual chance for implementing a flux approach in the CONECOFOR PMPs
Gli ultimi giganti?
Full text linkGli alberi che raggiungono un’altezza
contenuta e sono caratterizzati da foglie
relativamente piccole hanno dimostrato una
maggiore capacità di adattamento al clima
in ambito urbano rispetto ai cambiamenti
climatici. Lo dimostrano i risultati di
uno studio che ha indagato la capacità
degli alberi di adeguare la struttura
dello xilema al variare della crescit
Widening of xylem conduits and its effect on the diurnal course of water potential gradients along leaf venations
No full textIn plants, water flows from roots to leaves through the xylem vasculature following an axial gradient of water potential (��X). We hypothesized that xylem properties such as conduit widening govern the pattern of this gradient and determine the flow rate under the different ����X between leaves and soil occurring during any day. The steep gradient of ��X in leaf venations should strongly reflect the leaf physiology. Since stomatal conductance (gS) equilibrates the water losses through transpiration with the water flowing from soil to leaves, we expected gS to be synchronized with the maximum steepness of the gradient. We measured ��X and gS at the base of the apical leaflet and at the base of the petiole in leaves of Fraxinus excelsior from dawn to dusk. We found a slightly asynchronous diurnal course of ��X at the two different points along the leaf (��L���20 cm). ��X at the base of the apical leaflet decreased more rapidly in the morning and increased more slowly in the afternoon compared to ��X at the petiole base. This led to an original double-peaked pattern of ����X. A first peak (����X���-1 MPa) occurred two hours earlier than minimum ��X and was synchronized with the maximum gS. The second peak occurred after the gS drop in the afternoon, when the plant was likely under refilling. We demonstrated that a steep gradient of ��X develops in the main leaf vein and is strongly linked to maximum gS and potentially to other important aspects of leaf water relations. �� ISHS 2013
Sviluppo socio-economico delle Alpi nel terzo millennio: una minaccia per le risorse naturali?
Full text linkIl contributo delle aree assestate a fronte delle richieste poste dal protocollo di Kyoto: un esempio dalla Regione Veneto
Full text linkIl Protocollo di Kyoto consente ai Paesi inseriti nell’Annesso I, come l’Italia, di avvalersi delle attività legate alla Gestione Forestale come misura complementare per il raggiungimento degli obiettivi fissati in sede internazionale. Obiettivo del presente studio è realizzare un’indagine preliminare volta a proporre una prima valutazione del ruolo che possono assumere, in tale contesto, le aree assestate presenti nel nostro Paese.
Utilizzando il database «Gestione Piani di Assestamento» della Direzione Regiona- le Foreste ed Economia Montana del Veneto (PILLI e ANFODILLO, 2006) sono stati stimati lo stock e le capacità fissative delle fustaie assestate presenti nel territorio regionale. A tale scopo è stata utilizzata sia la metodologia proposta dalle Good Practice Guidance dell’Intergovernmental Panel on Climate Change, con l’impiego di fattori di espansione della biomassa (NABUURS et al., 2003), sia un modello funzionale basato sull’applicazione di equazioni allometriche (PILLI et al., 2006).
I risultati, oltre ad evidenziare la possibilità di pervenire ad una stima diretta delle capacità fissative di tali formazioni sfruttando le sole informazioni assestamentali già disponibili, eventualmente integrate da specifiche indagini, dimostrano le potenzialità offerte dall’applicazione di equazioni allometriche in loco dei fattori di espansione della biomassa ricavati da fonti bibliografiche
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