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The 4th National Report ex Art. 17 of the 92/43/EEC Directive in Italy (period 2013-2018) will try to fill a number of gaps still affecting the former versions of the Italian Reports, where territorial data were still missing for large parts of the country and the assessment was mostly based on the use of the expert opinion. Similar inconsistencies also emerged in other European countries (State of nature in the EU, EEA 2015). In order to reach this aim, a nationally shared protocol for monitoring the vegetation-based Annex I Habitats is currently under development. The most prominent issues addressed by the ongoing project are: i) fixing standardized, updated and scientifically grounded methodological tools, on the basis of the European guidelines (Evans & Arvela 2011, ETC-BD); ii) providing comparable data at national and European level; iii) harmonizing the territorially fragmented knowledge and iv) supporting nationally standardized measures for the conservation of terrestrial, brackish and freshwater Habitats. Promoted by the Italian Ministry for Environment (MATTM) and coordinated by the environmental agency ISPRA, the development of such a tool is being carried out by the Italian Society for Vegetation Science, with the support of a large team of experts. Open issues, such as the favourable reference values and the optimal thresholds for each considered parameter (range,area, structure and function), have to be dealt with, in a condition of large uncertainty. Due to its centrality in the assessment process, especially the concept of "typical species" should be developed with care, trying to combine the need for synthetic indicators with the great floristic diversity of the Italian Habitats. A clear definition of the parameters is crucial for a correct application of the monitoring protocol, to successfully contribute to the whole process of halting biodiversity loss in Europe.

Here we present an extensive overview of plant diversity values in Palaearctic grasslands for seven standard grain sizes from 0.0001 to 100 m². The data originate from 20 studies, including the Field Workshops of the Eurasian Dry Grassland Group (EDGG), ranging geographically from Spain in the west to Siberia in the east, from Sicily in the south to Estonia in the north and from the sea coast up to 3100 m a.s.l. The majority of data is from dry grasslands (Festuco-Brometea, Koelerio-Corynephoretea, Cleistogenetea squarrosae), but there are also some mesic, wet, saline, acidic, alpine and Mediterranean grasslands included. Among others, we compiled data from 1795 1-m², 1109 10-m² and 338 100-m² plots. In all cases we present mean, minimum and maximum richness for the seven grain sizes, plus, in cases where also terricolous bryophytes and lichens had been recorded, the same values for total “plant” species richness, non-vascular plant species richness and fraction of non-vascular plants. The maximum richness values were 82, 101 and 134 for all “plants”, and 79, 98 and 127 vascular plants at grain sizes of 1 m², 10 m² and 100 m², respectively (all in Transylvania, Romania). Our overview comprises new, hitherto unpublished world records of vascular plant species richness at the scales of 0.0001 m² (9) and 0.001 m² (19, both shoot presence), from meso-xeric, basiphilous grasslands in Navarre, Spain, which is much higher than the previously known maxima. The highest values of non-vascular plant richness at 1 m², 10 m² and 100 m², respectively, were 49, 64 and 64, respectively (all in Sedo-Scleranthenea communities of Öland, Sweden, and Saaremaa, Estonia). In general, the dry, alpine and Mediterranean grasslands were much richer than the studied mesic, wet or saline grasslands at any spatial scale. The presented set of mean, minimum and maximum values and their metadata is publically available and will be continuously updated. These data can serve as a reference of “normal” richness, both in fundamental and applied research. To facilitate the application, we provide an easy formula based on the power-law species-area relationship that allows the estimation of richness values at intermediate grain sizes not included in our dataset. In conclusion, our data emphasise the role of Palaearctic grasslands as global hotspot of small-scale vascular plant diversity, while at the same time highlighting that in some grassland types also the bryophyte and lichen diversity can be extraordinarily high.

Allium paniculatum L. is commonly recorded from the Euro-Mediterranean and Irano-Turanian regions. Evidence from literature and herbarium collections revealed that many different taxa of A. sect. Codonoprasum Rchb., all characterized by big size, diffuse and densely flowered umbrella, very long spathe valves, long pedicels, and cylindrical-campanulate perigon, have been wrongly attributed to this species thus affecting records on its geographic distribution and morphological characterization. In order to define the true identity of A. paniculatum, we analyzed specimens coming from the type locality (Don River), and provided details on morphology, ecology, karyology, leaf anatomy, seed morphology and seed coat micro-sculpturing. Taxonomic and phylogenetic relationships with related species of sect. Codonoprasum and with other taxa of different sections were investigated by means of morphological characters and molecular data from the internal transcribed spacers (ITS) nrDNA and the trnH-psbA cpDNA region. Maximum parsimony and Bayesian inference analyses of molecular data recovered two main clades in A. sect. Codonoprasum and clearly separated A. paniculatum from related taxa. The taxonomic implications of these patterns of relationships are discussed. To our knowledge, this is the first study documenting in-depth phylogenetic relationships within A. sect. Codonoprasum.

A syntaxonomical revision of the class Querco-Fagetea sylvaticae in Sicily, based on literature data and unpublished relevés, is presented. This class groups the mesophilous woods characterized by the dominance of deciduous trees (e.g. Fagus sylvatica, Quercus sp. pl., Acer sp. pl.), and more rarely by conifers (Taxus baccata, Pinus nigra subsp. calabrica), as well as by other broadleaved trees, such as Betula aetnensis, Populus tremula, Castanea sativa. In Sicily, these woody communities are widespread in the northern and north-eastern districts of the island, chiefly on the highest peaks (Madonie, Nebrodi, Peloritani, and Etna). This class is represented in Sicily by two, both floristically and ecologically well differentiated orders: Fagetalia sylvaticae, with the sole alliance Geranio versicoloris-Fagion sylvaticae, and Quercetalia pubescenti-petraeae, with the endemic alliance Pino calabricae-Quercion congestae. On the whole, 22 associations have been recognized within the class Querco-Fagetea and for each of them nomenclature, floristic assessment, ecology, syndinamic relationships, and chorology are examined.

A new species of Silene sect. Dipterosperma, named S. nefelites C. Brullo, S. Brullo, Giusso & Ilardi spec. nova, from Sicily is described and illustrated. Some of the characteristics are pinnately nerved leaves, 10–25 mm long bracts and 10– 15 mm long filaments. It is a therophyte occurring on the top of Mt. Erice, near Trapani, where it grows on calcareous rocky stands. Its relationships with S. colorata and allied species are also examined. A key to the Sicilian species belonging to S. sect. Dipterosperma is provided Eine neue Art von Silene sect. Dipterosperma, nämlich S. nefelites C. Brullo, S. Brullo, Giusso & Ilardi spec. nova von Sizilien wird beschrieben und illustriert. Einige der Merkmale sind fiedernervige Blätter, 10–25 mm lange Brakteen und 10– 15 mm lange Filamente. Sie ist ein Therophyt, der im Gipfelbereich des Mt. Erice bei Trapani auf Kalkfels-Standorten vorkommt. Die Beziehungen zu S. colorata und verwandten Arten wurden studiert. Weiters bringen wir einen Bestimmungsschlüssel für die sizilianischen Arten von S. sect. Dipterosperma

The 4th National Report ex Art. 17 of the 92/43/EEC Directive in Italy (period 2013-2018) will try to fill a number of gaps still affecting the former versions of the Italian Reports, where territorial data were still missing for large parts of the country and the assessment was mostly based on the use of the expert opinion. Similar inconsistencies also emerged in other European countries (State of nature in the EU, EEA 2015). In order to reach this aim, a nationally shared protocol for monitoring the vegetation-based Annex I Habitats is currently under development. The most prominent issues addressed by the ongoing project are: i) fixing standardized, updated and scientifically grounded methodological tools, on the basis of the European guidelines (Evans & Arvela 2011, ETC-BD); ii) providing comparable data at national and European level; iii) harmonizing the territorially fragmented knowledge and iv) supporting nationally standardized measures for the conservation of terrestrial, brackish and freshwater Habitats. Promoted by the Italian Ministry for Environment (MATTM) and coordinated by the environmental agency ISPRA, the development of such a tool is being carried out by the Italian Society for Vegetation Science, with the support of a large team of experts. Open issues, such as the favourable reference values and the optimal thresholds for each considered parameter (range, area, structure and function), have to be dealt with, in a condition of large uncertainty. Due to its centrality in the assessment process, especially the concept of "typical species" should be developed with care, trying to combine the need for synthetic indicators with the great floristic diversity of the Italian Habitats. A clear definition of the parameters is crucial for a correct application of the monitoring protocol, to successfully contribute to the whole process of halting biodiversity loss in Europe.

Silene kemoniana, a new species of the section Dipterosperma from NW Sicily, is described and illustrated. It is a therophyte that occurs in mountains near Palermo, where it grows on Mesozoic limestones in xerophilous garigues. Its relationships with S. colorata and allied species are also examined. A key of the species belonging to sect. Dipterosperma is provided. Se describe e ilustra Silene kemoniana, una nueva especie del NW de Sicilia perteneciente a la sección Dipterosperma. Se trata de un terófito que habita en algunas montañas próximas a Palermo, donde crece sobre calizas mesozoicas entre matorrales mediterráneos xerófilos. Se estudian sus relaciones con S. colorata y otras especies próximas. Se ofrece una clave para todas las especies pertenecientes a la sect. Dipterosperma.

After a general outline on the syntaxonomical framework of the class Pegano harmalae-Salsoletea vermiculatae Br.-Bl. & O. Bolos 1958, the occurrence of this vegetation in the Italian territory is examined. In Italy, this vegetation is mostly found on clayish or marly substrata, particularly if slightly enriched with nitrates and chlorides. With reference to the Rivas-Martı´nez bioclimatic classification, the Italian stands have an infra- to thermo-Mediterranean thermotype (marginally up to the meso- Mediterranean one) with dry or arid ombrotype. In particular, this vegetation is well represented in Sicily, while in Sardinia and along the Italian Peninsula, it progressively becomes more rare and localized. Altogether, 21 associations are recognized, 11 of which are described here for the first time. The surveyed associations are ascribed to the following alliances: Salsolo oppositifoliae-Suaedion mollis (linked to less disturbed and more thermo-xeric habitats) and Artemision arborescentis (more disturbed and less thermo-xeric habitats). Finally, some conservation issues are discussed.

Allium cithaeronis, a new species of A. sect. Scorodon from Greece is described and illustrated. Its chromosome number (2n=16), karyogram, leaf anatomy, ecology, taxonomical relationship are examined. For some morphological features, such as exerted stamens from perigon and tuberculate lobes in the upper part of the ovary,it represents a very isolated species within the A. sect. Scorodon.

Allium achaium Boiss. & Orph. ex Boiss. (Alliaceae), a critical and misappreciated species of Greek flora is investigated from taxonomic point of view and illustrated. It belongs to A. sect. Codonoprasum and shows close relationships with the taxa of the A. stamineum Boiss group. Besides, its karyology, ecology and distribution are examined.

Il lavoro analizza i risultati di indagini micromorfologiche su taxa annuali del genere Astragalus. Le analisi morfometriche e quelle ultrastrutturali condotte al SEM evidenziano modelli d'architettura differenti e di rilevanza tassonomica nel gruppo.

Basing on literature data and unpublished relevés from Sicily, a survey of the syntaxa belonging to the class Lygeo-Stipetea Rivas-Martínez 1978 is presented. This perennial vegetation is characterized by the dominance of big caespitose hemicryptophytes, and it is widely distributed in Sicily from the sea level up to 1500 m a.s.l. The class is represented in Sicily by two orders, floristically and ecologically well differentiated: Lygeo-Stipetalia, including the sole alliance Moricandio-Lygeion exclusively of clayey substrates, and Hyparrhenietalia hirtae, including five alliances (Hyparrhenion hirtae, Avenulo cincinnatae-Ampelodesmion mauritanici, Thero-Brachypodion ramosi, Bromo-Oryzopsion miliaceae, and Arundion collinae) occurring on various substrates. Within the class, 50 associations have been recognized. To support the syntaxonomic proposal, a multivariate numerical analysis, considering literature and personal data, has been performed. Nomenclature, floristic settlement, ecology, syndynamism and chorology are examined for each syntaxon.

Oggetto di questo studio è una singolare popolazione di Allium a fioritura autunnale, rinvenuta presso Reggio Calabria (Italia meridionale), la quale, per alcune caratteristiche vegetative e fiorali, rientra chiaramente nella sezione Allium. Le piante sono caratterizzate da un habitus robusto, foglie subcilindriche ampiamente fistolose, spata unica, caduca, slargata, con appendice fistolosa, lacerantesi lateralmente, infiorescenza globosa, densa, perianzio cilindrico con tepali conniventi, stami con filamenti laminari, dimorfi, gli esterni semplici e gli interni tricuspidati, e ovario con nettari ben sviluppati. Oltre alla fioritura tardiva (IX-X), gli individui di questa popolazione, presenti per altro in numero esiguo (

Dalle indagini morfologiche e cariologiche condotte è emerso che Allium paniculatum è una specie ben differenziata dagli altri taxa della sez. Codonoprasum, con corredo cromosomico poliploide, esaploide o triploide, probabilmente originatosi in seguito all’adattamento ad ambienti sinantropici in territori con bioclima marcatamente mesico, come si desume dalle esigenze ecologiche, dal periodo di fioritura estivo e dalla distribuzione geografica.

The Mediterranean temporary ponds are considered priority habitat in the Directive 92/43/EEC (habitat n. 3170*) and detailed information on their floristic composition and susceptibility to invasive species seems a central issue for their preservation, because the development and maintenance of seasonal vegetation is merely the resultant of the development and maintenance of its component individuals. Sardinia presents fairly large extensions of land where such habitats are still well represented, thought not investigated in depth. Basing on literature and unpublished data, a survey on the current phytosociological knowledge of the temporary ponds of Sardinia is presented. Our field studies led to the first recognition in the island of 22 associations, of which 13 were new. Out of them, 16 have been ascribed to the Cicendio-Solenopsion laurentiae, grouping ephemeral acidophilous spring vegetation with Mediterranean-Atlantic distribution, one to the Isoetion, that differs from the previous one in having an earlier drying up, and further 6 to the Verbenion supinae, grouping summergreen subnitrophilous prostrate vegetation linked to long-submerged sediments of the Euro-Mediterranean area. Besides of the phytosociological characterization, for eachy syntaxon the susceptibility to invasive species has been indexed, basing on the following criteria: status of the non-native species according to the classification of Pysek et al. (2004), occurrence and frequency of the non-native species, dispersal strategy of the same, kind of preferred habitat (natural/artificial).

As Sicily has been a central crossroads of human activity for thousands of years, it offers a major perspective on the Mediterranean weedy plant communities. This syntaxonomical survey of the Sicilian weedy vegetation groups together for the first time 30 plant associations, that have been described from the main and neighboring island in the last three decades. The surveyed vegetation is ascribed to the classes Papaveretea rhoeadis and Stellarietea mediae, whose floristic autonomy is here discussed, and to the orders Aperetalia spicae-venti and Papaveretalia rhoeadis for the former, Polygono-Chenopodietalia polispermi, Solano-Polygonetalia convolvuli, Thero-Brometalia and Urtico-Scrophularietalia peregrinae for the latter class. Most of the surveyed associations are linked to hoed cultivations. Major differences are determined by the tillage and watering regimes, on their turn related to the life-cycle of the cultivated plant.

A phytosociological survey on the orophilous dwarf-shrub vegetation of Mt. Troodos (Cyprus) is presented. Four associations are described, the first three being linked to the upper supramediterranean bioclimatic belt: Nepeto troodi-Hypericetum stenobotryos, dwelling the summit plateaux on ultramaphic sediments, Salvietum willeanae, substituting the previous one in hollow sites, where the snow-cover lasts longer, Onosmo troodi-Astragaletum chionistrae, colonizing eroded soils on steep, windy slopes, Alysso cyprici-Genistetum crudelis replacing the Nepeto troodi-Hypericetum stenobotryos at lower altitudes, within the lower supramediterranean belt. Due to the noteworthy floristic autonomy of the vegetation at issue, a new phytosociological class (Diantho troodi-Teucrietea cyprii) is proposed, which can be considered a synvicariant of similar endemic classes, described for the highest mountains of other isolated Mediterranean districts. Within the class a sole order (Diantho troodi-Teucrietalia cyprii) and one alliance (Hyperico stenobotryos-Alyssion troodi) have been recognized.

The grasslands characterized by the dominance of Brachypodium retusum occurring in Sardinia are examined. These communities, belonging to the Thero-Brachypodion ramosi alliance (Lygeo-Stipetea class), are quite widespread in the Island, where they usually grow on carbonate substrata from the sea level up to 1300 m of altitude. On the basis of several phytosociological relevés, it has been possible to recognize six associations well-differentiated from the floristic, ecological and syndynamic point of view. The autonomy of these associations is also supported by a numerical multivariate analysis based on quantitative data (dendrogram and P.C.A.). The associations surveyed are the following: Dorycnio suffruticosi-Stipetum offneri ass. nova, localized on summit plateaux at an altitude of 700-1200 m (CE Sardinia), Stipo bromoidis-Astragaletum verrucosi ass. nova, very rare and circumscribed to the coastal hills (W Sardinia), Triseto splendentis-Brachypodietum retusi ass. nova, colonizing more or less stabilized screes at 200-900 m of altitude (NE Sardinia), Asphodelo africani-Brachypodietum ramosi Biondi & Mossa 1992 corr., thermo-xerophilous community linked to coastal stands (S Sardinia), Ranunculo graminei-Brachypodietum retusi ass. nova, orophilous community growing on jointed rocky places at an altitude of 1100-1300 m (CE Sardinia), Melico ciliatae-Brachypodietum retusi ass. nova, found on the coastal screes of Figarolo islet (NE Sardinia). Besides, a floristic comparison among the hitherto known associations belonging to this alliance is given.

The results of a phytosociological survey on the orophilous vegetation dominated by dwarf, often thorny, scrubs occurring on the top of Mt. Troodos (Cyprus) are presented. The vegetation at issue ranges between 1500 and 1950 m, within the meso- and supramediterranean bioclimatic belts, where it dwells ultramaphic and serpentinitic substrata on windy slopes and summit plateaux. These plant communities face intense summer drought and cold winters, with av. two months of snow cover. The ombrotype of the dwelled sites ranges from subhumid to lower humid, with an av. rainfall about 1000 mm/year. Due to the human activity, secondary habitats became also available, mainly represented by sites with eroded soils, on which the original cover was mainly given by pine and juniper woods. From the floristic viewpoint, within this vegetation almost all the species are represented by Cyprian endemics, taxonomically isolated or related to E-Mediterranean taxa. This is given both by the geological peculiarity of Mt. Troodos and to the old geographic isolation of the island. Still there was a clear lull of literature data about this vegetation, as the only phytosociological contributions about the Cyprian vegetation focus on coastal areas or on woodlands. As the noteworthy floristic autonomy of the orophilous dwarf scrub vegetation at issue does not let to ascribe it to any known syntaxon, the following syntaxonomical scheme is here proposed: DIANTHO-TEUCRIETEA CYPRII cl. nov. CHARACTERISTIC SPECIES: Acinos troodi, Dianthus troodi, Euphorbia rigoi, Pterocephalus multiflorus, Saponaria cypria, Scorzonera troodea, Scutellaria cypria, Teucrium cyprium. DIANTHO TEUCRIETALIA CYPRII ord. nov. CHARACTERISTIC SPECIES: see class HYPERICO-ALYSSION TROODI all. nov. CHARACTERISTIC SPECIES: Aegialophila cretica var. alpina, Alyssum troodi, Anthemis plutonia, Arabis purpurea, Cynoglossum troodi, Hypericum stenobotrys, Scariola tetrantha, Thlaspi cyprium. Nepeto troodi-Hypericetum stenobotryos ass. nov. CHARACTERISTIC SPECIES: Nepeta troodi, Euphorbia veneris Onosmo troodi-Astragaletum chionistrae ass. nov. CHARACTERISTIC SPECIES: Astragalus echinus subsp. chionistrae, Onosma troodi, Sedum microstachyum Salvietum willeanae ass. nov. CHARACTERISTIC SPECIES: Salvia willeana Alysso cyprici-Genistetum crudelis ass. nov. CHARACTERISTIC SPECIES: Allium cyprium, Alyssum cypricum, Genista sphacelata var. crudelis.

The vegetation of mining dumps of SW-Sardinia includes several endemic or rare species, that have been confined to such artificial habitats by a millennial mining activity. The extreme edaphic specialisation of these species reflects with unusual fidelity the heterogeneity of substrata, therefore creating a system of plant communities that largely contributes to the environmental diversity of this part of the island. The phytosociological study presented in this paper recognized eight associations, distinguished by the cluster analysis in two main groups, the first including hemicrypto-chamaephytic vegetation, the second including nanophanerophytic garigues. Six associations are belonging to the first group, five of which newly described: Helichryso tyrrhenici-Dianthetum sardoi ass. nov., occurring on gross-grained, hard-sloping dumps deriving from the geologic unit of Gonnesa; Coincyo recurvatae-Helichrysetum tyrrhenici ass. nov., colonizing dumps made of metamorphitic flakes and finer particles; Resedo luteolae-Limonietum merxmuelleri ass. nov., colonizing small-grained mining dumps with high concentrations in sulphides and heavy metals; Ptilostemono casabonae-Iberidetum integerrimae ass. nov., replacing the previous one on older and more consolidated dumps, where the concentration of phytotoxic elements was reduced by the meteoric agents; Epipactidetum tremolsii ass. nov., colonizing muddy deposits originating from ferrous clay; Euphorbio cupanii-Santolinetum insularis Angiolini & Bacchetta 2003, occurring on very old, stabilized dumps. All these associations can be ascribed to the class Scrophulario-Helichrysetea Brullo, Scelsi & Spampinato, 1998. Within this class, a new Sardo-Corsican alliance, Ptilostemono casabonae-Euphorbion cupanii is here proposed, differentiated by a pool of rare or endemic species. In addition to the above- mentioned associations, it is proposed, as well, to include into the new alliance the Polygono scoparii-Helichrysetum tyrrhenici Biondi, Vagge, Fogu & Mossa 1996 corr., that was described for the gravelly riverbeds of Central-Southern Sardinia. As concerns the second group, two new association have been recognized: Dorycnio suffruticosi-Genistetum corsicae ass. nov., found on abandoned, well consolidated mining dumps, with an upper layer altered by pedogenetic processes; Polygalo sardoae-Linetum muelleri ass. nov., occurring in the vicinities of the mines on steep rocky slopes made of Paleozoic metalliferous limestones. Both of them can be ascribed to the alliance Teucrion mari Gamisans & Muracciole 1985, grouping the Sardo-Corsican aspects of Cisto-Lavanduletea Br.-Bl. in Br.-Bl., Molinier & Wagner 1940.

In epoca attuale, le culminazioni dei gruppi montuosi presenti sulle maggiori isole mediterranee risultano doppiamente isolate nei confronti di possibili migrazioni floristiche. Una prima barriera è rappresentata dal mare che circonda le isole, la seconda dalle peculiarità climatiche proprie dell’ambiente alto-montano, che impongono alle specie colonizzatrici adattamenti ecomorfologici ed ecofisiologici specifici. Negli ambienti montani insulari, le risorse particolarmente scarse, l’intensa radiazione solare, la forte ventosità e la marcata siccità estiva, solo in parte compensata dalle precipitazioni occulte, hanno condotto a straordinari fenomeni di convergenza evolutiva tra specie appartenenti a generi diversi. Nonostante l’isolamento attuale, tali ambienti sono accomunati da una grande somiglianza floristica, dovuta a gruppi di taxa affini, frammentati in popolazioni spesso limitate a un solo massiccio montuoso, ma la cui origine monofiletica appare evidente. Esaminando la struttura della vegetazione alto-montana delle isole mediterranee, si possono riconoscere due tipologie principali, spesso strettamente compenetrate: nella prima, paucispecifica e caratterizzata da specie a portamento arboreo o arbustivo, sono rappresentate essenzialmente Pinaceae, Cupressaceae, Rosaceae, Thymeleaceae e Berberidaceae; nella seconda, costituita da formazioni emicripto-camefitiche pulvinari più ricche di specie, sono rappresentate soprattutto le seguenti famiglie: Fabaceae, Plumbaginaceae, Boraginaceae, Plantaginaceae, Lamiaceae, Caryophyllaceae, Violaceae e Poaceae. Appartengono alla prima tipologia varie gimnosperme ed alcune angiosperme alquanto primitive, la cui filogenesi si svolse compiutamente già all’inizio del Terziario. Alcune di queste specie, come Juniperus hemisphaerica, Prunus prostrata e Daphne oleoides sono rimaste pressoché indifferenziate su gran parte dei massicci montuosi del Mediterraneo. Altre, appartenenti principalmente ai generi Pinus, Abies, Rosa, Berberis, in seguito alla frammentazione dell’areale originario, si sono segregate in specie vicarianti, pur mantenendo una connotazione marcatamente relittuale, testimoniata da una variabilità genetica intra e interpopolazionale molto bassa. E’ verosimile che specie di questo tipo abbiano dominato la fascia alto-montana in area mediterranea fino a tutto il Miocene e che molte di esse fossero entrate spontaneamente in una fase di declino in risposta all’instabilità climatica che si instaurò da 5,5 a 4,5 milioni di anni fa, in concomitanza con la crisi del Messiniano. Gli eventi determinati dalla ciclica evaporazione e reinondazione del Mediterraneo, legati a movimenti tettonici che periodicamente innalzavano la soglia dello Stretto di Gibilterra, si possono riassumere come segue: aumento ciclico dell’aridità, oscillazione delle fasce altitudinali, massiccia apertura di nuove nicchie ecologiche, aumento generale dell’intensità dei processi erosivi e della frequenza di frane catastrofiche. Questi fenomeni consentirono imponenti migrazioni floristiche, favorendo in modo particolare i taxa forniti di una variabilità genetica sufficiente a supportare una nuova radiazione adattativa. Le più alte quote delle montagne mediterranee vennero così raggiunte da una nuova coorte di specie, in massima parte evolutesi nei territori sub-desertici dell’Asia Minore e del Nord Africa e pertanto dotate di una notevole resistenza all’aridità, al disturbo meccanico e a bruschi sbalzi termici. Tali specie poterono migrare in tutto il bacino mediterraneo, colonizzando le scarpate continentali durante le fasi di regressione marina e, essendo di natura marcatamente pioniera, verosimilmente raggiunsero le alte quote risalendo i solchi di frana. Una volta giunte in quota, queste piante poterono occupare agevolmente gli spazi lasciati vuoti dal deperimento delle già menzionate gimnosperme ed angiosperme primitive, che avevano dominato fino ad allora. La radiazione adattativa dei gruppi che espansero il loro areale durante il Messiniano iniziò in concomitanza delle migrazioni stesse, e si intensificò in seguito all’isolamento derivato dalla trasgressione marina che pose definitivamente fine al Messiniano. Ne è derivato un interessante sistema di specie vicarianti la cui varietà aumenta progressivamente procedendo da Nord verso Sud e da Ovest verso Est, a testimonianza delle direttrici seguite dalle migrazioni anzidette. Queste specie sono per la quasi totalità rappresentate da camefite pulvinate, spesso irte di spine, e possiedono apparati vegetativi notevolmente più ridotti di quelli delle gimnosperme e angiosperme arcaiche a cui si sono venute progressivamente a sostituire. Pertanto è ipotizzabile che in un confronto basato sulle sole capacità di competizione interspecifica, sarebbero le specie arcaiche a prevalere. Tuttavia le osservazioni attuali sulla vegetazione alto-montana nelle isole mediterranee mostrano una tendenza opposta: forse le camefite si adattano meglio alle condizioni climatiche attuali, ma il disturbo legato all’attività umana, per la sua precoce comparsa e per la sua intensità, ha certamente contribuito in modo determinante al regresso della vegetazione legnosa in questi contesti.

Lygeum spartum grasslands from Crete have been studied by the application of the phytosocological method. A new alliance, Scorzonero creticae-Lygeion sparti and three new associations and have been recognized. The first, Limonio hyssopifolii-Lygeetum sparti occurs on halomorphyc badlands in the Sitia territory (NE Crete); the second Erodio crassifolii-Lygeetum sparti grows on heavily eroded clayey outcrops close to Hyerapetra (SE Crete); the third Convolvulo oleifolii-Lygeetum sparti, substitutes the previous one some Km eastward from Hyerapetra, on stratified marls alternated to conglomerates. Within the last association, two subassociations have been recognized: limonietosum roridi (typicum), grouping the aspects close to the sea, and fumanetosum laevipedis gathering the inland aspects. To evaluate the similarity among the relevés, a numerical multivariate analysis has been performed.

The authors examine the orophilous communities, occuring in the Central and Eastern Mediterranean area, characterized by the dominance of trees and shrubs belonging to the genera Juniperus, Abies and Pinus. These communities are localized in the supra- and oromediterranean belt and show a relict role. From the structural point of view, this kind of vegetation is usually bistratified, with a low dense shrubby layer and spaced tree layer; sometime the latter one is absent. This vegetation is floristically poor and characterized by prevalence of Coniferous, such as Juniperus sabina, J. foetidissima, J. excelsa, J. oxycedrus. J. hemisphaerica, J. communis, J. nana, Abies nebrodensis, A. alba, A. borisii regis, A. cicilica, and various taxa belonging to the cycle of Pinus sylvestris and Pinus nigra. Numerous shrubs of the genera Rosa, Daphne, Berberis, Prunus, Crataegus, Sorbus, Acer, etc. are here well-represented too. On the basis of personal unpubblished and literature data, a comparison among the various communities occuring in the Central and Eastern Mediterranean has pointed up that there is a remarkable flostical and structural homogeneity together with a series of geographical vicariants. From the phytosociological point of view, this justifies the arrangement of the aforsaid communities in one class only, Pino-Juniperetea, which is represented, in the examined area, by the order Juniperetalia hemisphaericae. This sintaxon comprises several alleances and suballeances which bear witness to a certain geographical isolation regarding some well-defined phytogeographical districts.