Vegetation and plant landscape of the “Gravine” in the Ionian coast . The phytosociological study of the vegetation and the geosynphyosociological analysis of the plant landscape of the Ionian arch Gravine are here presented. The aim of this paper is to give a first contribution on the knowledge of these particular biotopes that represent one of the most important geomorphologic and environmental characteristic of Apulia.
The study area, including the gravine system of Cripiano, Statte and Laterza territories, is located in the western part of Taranto Province, between the Murge area and the Ionian Sea. All the relieves are constituted by the lithotypes belonging to the formations of the Stratigraphic Series of Murge Limestone, which the highest outcropping type is represented by “Calcare di Altamura” and by other formations as: “Calcareniti di Gravina”, “Argille Subappenniniche” and “Calcareniti di Monte Castiglione” that crop out along little ravinements called “lame” present in the areas near the coast.
The elaboration of climate data of temperature and precipitations shows that the bioclimate is Mediterranean Pluviseasonal Oceanic wuth three bioclimatic belts:
• upper thermomediterranean belt: only for the Taranto station,
• low mesomediterranean for the station of Crispiano, Castellaneta and Marina di Ginosa,
• upper mesomediterranean for Matera station.
The vegetation study allowed the identification of the different vegetation typologies occurring in the territory, which are strictly related with the high environmental diversity due to the geomorphologic and microclimatic characteristics of the erosion gullies that often get narrower as canyons with vertical slopes. The vegetation has a great biogeographic interest because to the eastern-Mediterranean (Balkanic) floristic contingent, a good western component is associated, that contributes to the definition and to the synchorological differentiation of the syntaxa.
The following new associations have been described: Coronillo valentinae-Juniperetum turbinatae, Coronillo emeroidis-Pistacietum lentisci, Oleo sylvestris-Calicotometum infestae, Cardopatio corymbosi-Brometum erecti, Convolvulo elegantissimae-Stipetum austroitalicae, Stipo austroitalicae-Hyparrhenietum hirtae, Centaureo apulae-Andropogonetum distachyi, Ruto chalepensis-Salvietum trilobae, Chamaecytiso spinescentis-Cistetum eriocephali, Helianthemo jonii-Coridothymetum capitati, Asyneumo limonifolii-Saturejetum montanae, Phagnalo saxatilii-Saturejetum cuneifoliae, Medicago disciformis-Brachypodietum distachyi, Onobrychido aequidentatae-Stipetum capensis. To these, several new subassociations and variants are associated. The phytosociological definition of the Pistacia lentiscus and Olea europaea var. sylvestris maquis required the elaboration of our relevés with those published for the Ionian and the southern Adriatic coasts. The comparison allowed the description the following new associations: Junipero turbinatae-Pistacetum lentisci of the eastern Adriatic coast and Euphorbio dendroidis-Pistacetum lentisci of the Tremiti Islands. Furthermore, the new alliance Hypochoerion achyrophori of the central European Mediterranean has been described, within the order Trachynietalia distachyae and the class Helianthemetalia guttati.
The synphytosociological analysis allowed the identification of the following vegetation series:
• Ionian, calcicole-subacidophilous, climatophilous, thermomediterranean series also occurring in the mesomediterranean belt of the Aleppo Pine: Thymo capitati-Pino halepensis ∑;
• western-Adriatic, calcicole, climatophilous mesomediterranean sub humid and dry series of the holm-oak: Cyclamino hederifolii-Querco ilicis ∑;
• laertino-materane Murge, calcicole, subacidophilous, climatophilous, upper mesomediterranean series of the Macedonian oak: Teucrio siculi-Querco trojanae ∑;
• tavoliere foggiano, neutral-basophile, climatophilous mesomediterranean subhumid series of the Quercus virgiliana: Irido collinae-Querco virgilianae ∑.
The geosynphytosociological analysis allowed to recognize the following geosygmeta:
• Geosigmetum of the calcareous and calcarenitic southern an eastern sectors of the Ionain-Arch gravine;
• Geosigmetum of the firts soouther-eastern Murge terraces;
• Geosigmetum of the materana and laertina Murgia;
• Geosigmetum of the Ionain-Arche “lame” with subapennine clays,
• Microgeosigmeta of the calcareous walls.