1,721,046 research outputs found
Contributo alla conoscenza dei querceti supramediterranei e submontani della Calabria settentrionale
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Sull’ecologia delle foreste del Tilio-Acerion Klika 1955 in Molise e considerazioni sui caratteri cenologici e fitogeografici dei boschi di forra dell’Appennino centro-meridionale (Italia centrale e meridionale)
No full textOn the bases of releves recognized to the Eastern sector of the Matese Mountain (South Apennines), we analyzed a synecological and syntaxonomical meaning of the dominated Acer opalus ssp. obtusatum, Tilia plathyphyllos, Ostrya carpinifolia e Acer cappadocicum subsp. lobelii forests. These broadleaved mixed woods, are belonging to the Tilio-Acerion Klika 1955 alliance (in the Fagetalia sylvaticae order, and Querco-Fagetea class). These fragmented coenoses, normally considered as relics stands, are located in specific morphological conditions (‘ravine woodlands’), like in the steep slopes and ravines, at the bottom of shady steep-sided valleys and on colluvial deep soils at the foot of slopes. We defined the new association Aro lucani-Aceretum lobelii, a typical Southern communities with high number of Endemic entities. The chorological analysis and a comparison with other Central and Southern Apennine similar forests, emphasize the Illirical floristic connotation and extraordinary biogeographical significance for the Molise region forests
Indagini preliminari sui ginepreti a Juniperus communis ssp. hemisphaerica (J. & C.Presl) Nyman dei Monti Picentini (Appennino meridionale)
No full textDowny oak woods of Italy: phytogeographical remarks on a controversial taxonomic and ecological issue
Full text linkThe importance of downy oak as an integral component of the "submediterranean" woods has been underscored in many studies. Nevertheless, terms like "submediterranean" and "downy oak" are some of the most faintly understood concepts in the European phytogeographical and taxonomical research. Downy oak is well known to be a problematic taxon: the name "Quercus pubescens" (= Q. humilis) piles together populations characterized by an increasing phenotypic and genomic polymorphism along north-south gradients, which is commonly explained as the result of a "founder effect" given by a relatively fast post-glacial re-colonization of the northern stands through rare long-distance dispersal events.
On the other hand, the southern polymorphism of the downy oak provides evidence for geographic/environmental selection driven by different edaphic conditions along clinal gradients of cold and drought stress, even if the distinction of different species is blurred by systematic hybridization and introgression, enhanced by the recent deforestation.
Since downy oak occurs widely all through the Italian Peninsula, we tried to detect some ecological and geographical borders which might be useful to identify climate-vegetation feedback mechanisms as well as to sharpen the syntaxonomical and systematic investigation on such a critical species complex. Our work is based on a well-distributed geo-referenced set of vegetation data, combined with layers of environmental variables (elevation, climate, soil chemistry). The statistical significance of the correlation between vegetation and environmental data has been evaluated through the Mantel's test.
Our results suggest that there are some borders in the distribution/prevalence of morphologic traits of "Q. pubescens" (regarded here as a species complex). These borders are not limited by sharp ecological or geographical gaps but instead reflect patterns of selection and phenotypic variability in key traits of the geographical range
Downy-oak woods of Italy: phytogeographical remarks on a controversial taxonomic and ecologic issue
No full textThe importance of downy oak as an integral component of the "submediterranean" woods has been underscored by many studies. Nevertheless, terms like "submediterranean" and "downy oak" are some of the most poorly understood concepts in European phytogeographic and taxonomic research. Downy oak is well known to be a problematic taxon. The name "Quercus pubescens" (= Q. humilis) combines populations characterized by increasing phenotypic and genomic polymorphisms along north-south gradients, which is explained as the result of a "founder effect" produced by a relatively fast post-glacial re-colonization of the northern areas through rare long-distance dispersal events.
On the other hand, polymorphisms of downy oak in the south provide evidence for geographic/environmental selection driven by different edaphic conditions along clinal gradients of cold and drought stress, even if the distinction of different species is blurred by systematic hybridization and introgression, which have been enhanced by recent deforestation.
Because downy oak occurs widely throughout the Italian Peninsula, we tried to detect some ecological and geographical borders, which might be useful to identify climate-vegetation feedback mechanisms as well as to sharpen the syntaxonomical and systematic investigation of such a critical species complex. Our work is based on a well-distributed geo-referenced set of vegetation data, combined with layers of environmental variables (elevation, climate, soil chemistry). The statistical significance of the correlation between vegetation and environmental data has been evaluated through the Mantel test.
We assessed that:
• the ecological amplitude of downy oak along the Italian peninsula increases southward;
• the maximum variance in ecological conditions is found in Sicily, where the morphologic variability of downy oak is also maximized and where potential competitors, like Quercus frainetto, Q. trojana, Carpinus orientalis, and others, are missing;
• discontinuities in the distribution/prevalence of morphologic traits of Q. pubescens (regarded here as a species complex) are not determined by sharp ecological or geographical gaps but instead reflect patterns of selection and phenotypic variability in key traits of the geographical range;
• the Ellenberg T and U indicator values for the flora of Italy are correlated well with temperature and precipitation
Floristic changes along the topographical gradient in montane grassland in Monti Picentini (Campania, South-Western Italy)
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Zonazione altitudinale della vegetazione di alcuni rilievi dell'Appennino meridionale e sue implicazioni fitostoriche
No full textCurrent methodological praxis in present day plant ecology and vegetation science, makes remarkably difficult to treat topics dealing with floristic changes along gradients, when qualitative aspects, based on biogeographical patterns are involved. Due to this, some outstanding “anomalies” in the altitudinal zonation of vegetation in southern Apennines and in the main islands, have traditionally been neglected or underestimated in their explanatory capacity for long-term vegetation processes. In this sense, patterns of floristic changes along topographical gradients observed in the Southern Italian ridges, from Monti Picentini (Campania) to Etna (Sicily) might be crucial for the interpretation of events and genesis of the plant cover of that part of peninsular Italy.
Here, the local ranges of some emblematic species are taken into account. Similarity in their sequences along local “catenas” with analogues in other regions of Southern Eurasia, are here used to infer modes of colonization and altitudinal stratification mirroring major events of Neogene climatic and paleogeographical changes.
In particular the patterns of altitudinal clustering of some taxa in Monte Etna, seems to be of major relevance for the detection of “fossil” zonations related to ancient environmental scenarios. The local behaviour of Pinus nigra s.l compared to its behaviour in the surrounding massifs and in other S-E European locations, suggests a pervasive persistence of Late-Miocene distribution patterns related to the connections with south and eastern Mediterranean landmasses of the emerging Italy of Late-Neogene
Floristic changes along the topographical gradient in montane grasslands in Monti Picentini (Campania, SW Italy)
No full textPopulations of xerotolerant species (Achnatherum calamagrostis, Stipa crassiculmis subsp. picentina, are scattered along a wide altitudinal gradient on slopes at mid- and high elevation in Monti Picentini, a subcoastal mesozoic limestone ridge in Tyrrhenian Southern Italy.
Their stands are widespread in grasslands of mostly secondary origin. At lower altitudes these grasslands replace former deciduous forest communities dominated by oaks or beech, while at higher altitudes they reach the summits, where they apparently merge into the remnants of the still partially grazed, zonal climatogenic, grasslands ranging above the local tree-line.
Nevertheless primary stands of these grasslands are to be found around the many clusters of highly dynamic sites of the montane and sub-alpine levels, scattered around screes and rocky outcrops of the prevalently dolomitic morphology of the slopes. This virtual continuity of non arboreal communities across more than 1000 metres of the local topographical gradient, where azonal, relic stands of Pinus nigra s.l. are transitional between the grasslands and the surrounding zonal broadleaved forest vegetation, stresses patterns of the coenological changes between Festuco-Brometea and Elyno-Seslerietea along the catena, which suggest fragmentary persistence of a paleozonation
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