1,720,982 research outputs found
Analysis of snowfall series observed during long periods in four meteorological stations in the Italian territory
No full textLimite superiore degli alberi e deficit termico. Il limite dei faggeti nell’Appennino settentrionale.
No full textFra tutti i limiti di vegetazione il limite degli alberi è il più evidente e il più rilevante. Il limite altitudinale degli alberi è un importante confine ecologico, ed è, in generale, accettato che il fattore chiave sia costituito da un deficit termico (1). Ciò mette in evidenza come la variazione climatica possa, contestualmente ad altri fattori (es. microtopografico, geomorfologico, antropico), concorrere ad uno spostamento altitudinale del limite degli alberi. Sono stati fatti molti tentativi per definire il limite superiore degli alberi in correlazione a qualche isoterma (2). La maggior parte degli studi si riferiscono a limiti altitudinali di alberi sempreverdi, in particolare conifere (1,2). Questi risultati non possono essere trasposti all’Appennino settentrionale dove il faggio (Fagus sylvatica L.) forma il limite superiore degli alberi. Le caratteristiche del limite degli alberi formato da questa latifoglia sono completamente diverse: Fagus sylvatica è una specie competitrice che forma un limite degli alberi netto (1). Come conseguenza limite degli alberi e limite del bosco coincidono. Alberi isolati e contorti dipendono dall’impatto antropico e da opportunità dovute alla geomorfologia. Nell’Appennino settentrionale il limite degli alberi si riscontra solo sulle cime più elevate dal Passo della Cisa all’Alta Valle del Reno (3). Gli studi sulle relazioni spazio-temporali tra questo limite e il clima, come pure altri fattori ambientali, sono completamente mancanti in Italia.
Il caso studio preso in considerazione è il versante Emiliano dell’Appennino settentrionale dalla Provincia di Parma a quella di Bologna in aree protette (Parchi) della Regione Emilia Romagna dove si riscontra un limite di tipo climatico. Considerando questo ambito abbiamo valutato a) l’attuale distribuzione del limite degli alberi nell’Appennino settentrionale a partire da carte fitosociologiche alla scala 1:25 000 disponibili (4,5,6,7) b) la distribuzione altitudinale dei valori critici per il faggio di alcuni parametri termici noti in letteratura (8, 9,10,11) per un’identificazione di un limite potenziale (climatico); c) il grado di coincidenza tra i valori limitanti dei parametri climatici e il limite attuale.
I dati termici sono stati ottenuti da 7 stazioni appenniniche poste a differenti quote, ricavandone il gradiente altitudinale e identificando le quote dove i loro valori assumevano valori ritenuti critici per il faggio
Effects of global climate change on freshwater biota: a review with special emphasis on the Italian situation
No full text
ECONOMIC, ENVIRONMENTAL AND ENERGY ASSESSMENT OF THE TURIN-LYON HIGH-SPEED RAIL
No full textOne of the best known cases of struggle for the commons in Italy, characterized by bitter controversies over the last 20 years, is the popular opposition to the construction of the High Speed Railway line (HSR, “TAV” in Italian) between Turin and Lyon, designed to cross the Susa Valley (at the Italian-French border) and the Alps. This HSR project still carries, in spite of twenty years of continuous updating and reworking, a great deal of unsolved environmental and economic issues. An issue of insufficient cost-benefit balance has recently come to clear evidence, especially in view of the non-negligible passenger and freight traffic decrease along the Turin-Lyon direction. The most important aspects dealing with economic costs and claimed benefits, energetic considerations, legal constraints, environmental impact, health impact potential, and the negative experience of other projects, are discussed: they all suggest that the High-Speed Train Turin-Lyon is not a priority for Italy and France, and its construction should be immediately stopped
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Trends of some high quantiles of average and extremes inter-arrival times and rainfall depths at daily scale for an Italian Sub-Alpine area.
Full text linkModeling of rainfall statistical structure represents an important research area in hydrology, meteorology,
atmospheric physics and climatology, because of the several theoretical and practical implications. The statistical
inference of the alternation of wet periods (WP) and dry periods (DP) in daily rainfall records can be achieved
through the modelling of inter-arrival time-series (IT), defined as the succession of times elapsed from a rainy day
and the one immediately preceding it. It has been shown previously that the statistical structure of IT can be well described by the 3-parameter
Lerch distribution (Lch). In this work, Lch was successfully applied to IT data belonging to a sub-alpine
area (Piemonte and Valle d’Aosta, NW Italy); furthermore the same statistical procedure was applied to daily
rainfall records to ITs associated. The analysis has been carried out for 26 daily rainfall long-series ( 90 yr of
observations). The main objective of this work was to detect temporal trends of some features describing the statistical
structure of both inter-arrival time-series (IT) and associated rainfall depth (H). Each time-series was divided on
subsets of five years long and for each of them the estimation of the Lch parameter was performed, so to extend
the trend analysis to some high quantiles
The Turin-Lyon High-Speed Rail: An Economic, Environmental and Energy Assessment
No full textOne of the best known cases of struggle for the commons in Italy, characterized by bitter controversies over the last 20 years, is the popular opposition to the construction of the High Speed Railway line (HSR, “TAV” in Italian) between Turin and Lyon, designed to cross the Susa Valley (at the Italian-French border) and the Alps. This HSR project still carries, in spite of twenty years of continuous updating and reworking, a great deal of environmental and economic issues. An issue of insufficient cost-benefit balance has recently come to clear evidence, especially in view of the non-negligible passenger and freight traffic decrease along the Turin-Lyon direction. The most important aspects dealing with economic costs and claimed benefits, energetic considerations, legal constraints, environmental impact, health impact potential, and the negative experience of other projects, are discussed: they all suggest that the High-Speed Train Turin-Lyon is not a priority for Italy and France, and its construction should be immediately stopped
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