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Variazione di caratteri strutturali dei castagneti del Parco Regionale dei Castelli Romani in relazione all'età di ceduazione.
No full textTratti funzionali di specie arboree rappresentative della vegetazione forestale del Parco Regionale dei Castelli Romani
No full textLe variazioni della struttura e della ricchezza in specie di una comunità vegetale influenzano la capacità di funzionamento del sistema. Quando le piante sono sottoposte a condizioni di stress si manifestano variazioni nelle caratteristiche morfologiche, soprattutto a carico della foglia, con ripercussioni sulla capacità fotosintetica e quindi sulla produttività. Ne consegue che la valutazione dello stato di funzionamento dei sistemi vegetali è legata allo studio delle variazioni strutturali e funzionali. L'obiettivo della presente ricerca, nell'ambito di uno studio più ampio teso a caratterizzare le differenze strutturali dei tipi vegetazionali presenti nel Parco Regionale dei Castelli Romani ed il loro stato di funzionamento, è stato quello di analizzare alcuni parametri fisiologici e morfologici fogliari delle specie arboree più rappresentative
Plant biomass and leaf area index (LAI) variations in the broadleaf mixed forests at Castelporziano Estate (Rome)
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Shrub structure and species composition as determinant of microclimatic patchiness in the Mediterranean maquis.
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Variation in shrub structure and species co-occurrence in the Mediterranean maquis.
No full textThe structure of the Mediterranean maquis developing inside the Presidential Estate of Castelporziano (S-SW of Rome) was due to mixture of different evergreen species. On an average six species co-occurred in shrub formation, the highest frequency being of Cistus incanus (80%), Erica multiflora (73%), Smilax aspera (53%) and Quercus ilex (50%). Discriminant analysis indicated that shrub volume was the most discriminating trait among the analysed shrub traits (height, volume, crown height, crown depth, major
axis and minor axis of the crown, crown projection at soil, crown volume, leaf area index). On the base of shrub volume, three different sizes of shrubs were defined by cluster analysis: small (S), medium (M) and large (L) shrubs and they were characterised by a volume of 1.9±1.5m3, 13.1±4.8 m3 and 34.9±8.8 m3 respectively. The considered maquis stand was constituted by 1050±300 shrubs ha-1, corresponding to a total shrub volume of 7793±1401 m3 ha-1; the frequency of S, M and L shrubs was 63%, 31% and 6%
respectively. Number of species increased from S to L shrubs: S were constituted by 4.8±1.7 species, M by 7.4±1.6 and L shrubs by 8.3±0.8. Cistus incanus, Daphne gnidium, Erica multiflora, Pistacia lentiscus and Rosmarinus officinalis of small height (< 1 m) occurred mainly in S shrubs, while Arbutus unedo, Erica arborea, Phillyrea latifolia and Quercus ilex (height = 1.4±0.3 m) in medium and large shrubs. The impact of shrub size on the Mediterranean maquis resulted in a patchiness of microclimatic variations showing the buffering effect of the shrub size: 78% of the study area was covered by shrubs having 4% and 94% reduction of air temperature and light transmittance respectively, and 10% and 165% increase of air humidity and soil water content respectively.
The remaining 22% of the study area was uncovered and directly subjected to the climate of the zone
Sustained activation of Raf/MEK/Erk pathway in response to EGF in stable cell lines expressing the hepatitis C virus (HCV) core protein
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