Bryophyte coastal vegetation of the Cilento and Vallo di Diano National Park (S Italy) as a tool for ecosystem assessment

Abstract The bryophyte vegetation of the coastal area of the Cilento and Vallo di Diano National Park has been investigated. The phytosociological study has emphasized the occurrence of many associations of the phytosociological classes Barbuletea unguiculatae, Pleurochaeto squarrosae-Abietinelletea abietinae, Cladonio digitatae-Lepidozietea reptantis, Grimmietea anodontis, and Frullanio dilatatae-Leucodontetea sciuroidis. Among these, Barbuletum convolutae, Didymodonto vinealis-Tortuletum muralis, and Funarietum hygrometricae show a strong human impact. On the contrary, the epiphytic associations (Syntrichietum laevipilae, Leucodonto sciuroidis-Leptodontetum smithii, and Fabronietum pusillae), as well as Tortelletum papillosissimae, Rhynchostegielletum algirianae, Tortello flavovirentis-Trichostometum crispuli, and Rhynchostegietum megapolitani, show a good degree of naturalness and air purity. This is revealed by the bryovegetational analysis based on biological and ecological parameters (life form, ratio St/We, life strategy, sensibility to air pollution and human impact) that can be interpreted to provide useful information about the quality and the health of the environment. Moreover, a new association, Gongylanthetum ericetori, is described here.


Introduction
The Cilento and Vallo di Diano National Park (PNCVD), the second largest park in Italy (181.048,00 ha), is located in the southern part of Italy stretching from the Tyrrhenian coast to inland including a large area of the Southern Campania Apennines. For the uniqueness of this environment, it has been included in the UNESCO list of World Heritage Sites since 1998 and, for its great geological heritage, in the European Geopark Network assisted by UNESCO since 2010. Within the area of the Park, 28 SIC (Siti di Importanza Comunitaria) and 8 ZPS (Zone di Protezione Speciale) are recognized. In particular, the coast, although subject to anthropogenic transformations in sandy areas, presents some of the most interesting areas of the whole Mediterranean basin, especially those characterized by vertical inaccessible cliffs, such as the calcareous Capo Palinuro promontory and the Infreschi coast. The montane landscape is equally interesting; in these areas it is possible to recognize some old-growth forests and persistent woodlands in the majority dominated by Quercus cerris L. and Fagus sylvatica L. that are outstanding hotspots of forest biodiversity Brunialti et al. 2010;Corona et al. 2010;Manes et al. 2010;Marchetti et al. 2010).
In this study, the bryophyte vegetation was used to obtain information on the environmental quality. In fact, the bryophytes play a significant ecological role as pioneer plants in the colonization of hard environments as well as bioindicators in the evaluation of the air quality. The bryophytes, neglected in the past even by botanists, are now being re-evaluated for environmental issues. In this respect, the role of bryophyte vegetation is important in the ecosystems as an intermediary between man and environment.
Lower Liassic and Upper Triassic while the inner cliffs consist of platform limestones, local calcareous re-sediments of the Upper Cretaceous and Middle Liassic (Bonardi et al. 1988). Along the coast, it is possible to recognize three main lithological complexes corresponding to the Carbonatic, Sandstoneconglomeratic, and Marly-clayey systems. The different geological nature of the Park (flysh of Cilento and dolomitic limestone) leads to a very different profile and topography of the coastline which is sweeter to the north (up to Palinuro), and rougher and almost, inaccessible at Capo Palinuro, in the southern sector.
The coastal area of PNCVD is included in the Mediterranean climatic region and is characterized by a bioclimate Mediterranean pluviseasonal oceanic (Rivas Martinez et al. 2004). For the climatic data, we refer to the meteorological stations of Capo Palinuro (184 m a.s.l.) and Casalvelino (189 m). In particular, the thermotype is thermomediterranean with mean annual temperature of 17.88C in both the meteorological stations. The mean annual precipitations are 729.7 mm at Capo Palinuro and 1081.49 mm at Casalvelino; on the basis of the precipitation values, the ombrotype ranges from subhumid to humid.

Material and methods
The field work was carried out in the coastal area of the Park between Tresino headland and Infreschi Coast (Figure 1).
The nomenclature of the species follows Aleffi et al. (2008).
The exsiccata are kept in Herbarium of the Department of Biological, Geological and Environmental Sciences of the University of Catania (CAT).  (Table I) This association has been observed on shady and slightly humid soil along the beaten pathways at Piano Cupo, Punta Tresino and Punta Infreschi. It is a terricolous, meso-xerophytic, photo-sciophytic community, growing on disturbed soil with medium nutrient content and preferably with strong human impact ). Rather diffused in C. Europe, in the Mediterranean region it is signaled from Spain, C. Italy and Sicily.

Phytosociological study
Trichostomo crispuli-Aloinetum aloidis Guerra & Varo 1981 (Table II) A terricolous, meso-xerophytic, photo-sciophytic bryocenosis found on compact, slightly exposed and xeric soil at Punta Tresino and Porto Palinuro in the ambit of the parasteppic vegetation with Ampelodesmos mauritanicus. It is a South temperate-Mediterranean association widespread in the Iberian Peninsula, occurring also in France, N. Africa, S. Italy and Sicily.
Weissietum tortilis Neumayr 1971 (Table III) It was found in rock crevices with accumulated soil in open and sunny places at Porto Palinuro, and at Punta Infreschi in the ambit of the coastal maquis with dominance of J. phoenicea, P. lentiscus, Cistus sp.pl. Weissietum tortilis ecologically behaves as a terricolous, xerophytic, photophytic association. It is a temperate-Mediterranean association known from some Central and Southern European territories and Sicily.
Trichostomo brachydontii-Didymodontetum vinealis Privitera & Puglisi 1989 (Table IV) This association colonizes dry and quite shady soil within the maquis with P. lentiscus and M. communis. It is a terricolous, xerophytic, sub-sciophytic association. Characteristic species of the association are Didymodon vinealis and Trichostomum brachydontium, the latter being considered a cognate species of the maquis. The association is known from Sicily and Central-Southern peninsular Italy.
Didymodonto vinealis-Tortuletum muralis Privitera & Puglisi 1996 (Table V) It was found in open, sunny places, on walls and limestone outcrops with accumulated soil near the settlement of S. Maria Castellabate and Porto Palinuro. It is a terri-saxicolous, photophytic, xerophytic association, widespread in anthropic areas. It has been reported from Central Italy and from many localities of Sicily and Southern peninsular Italy.

Tortelletum papillosissimae
Puglisi 2010 (Table VI) The community was found on loose soil and on the rocks with sandy soil accumulated, in dry and more or less exposed places facing the sea in the  ambit of the maquis with dominance of Juniperus phoenicia. Ecologically, it behaves as a xerophytic, thermophytic community. Characteristic of the association is Tortella flavovirens var. papillosissima, known only from Spain, Balearic Islands and Linosa ; this taxon represents a new record for peninsular Italy. It is almost constantly accompanied by Tortella flavovirens var.
flavovirens, characteristic of Tortellion flavovirentis, a psammophytic alliance with a Mediterranean-Atlantic distribution. Up to now, this association is known only in Sicily from Linosa Island (Puglisi 2010).
Tortello flavovirentis-Trichostometum crispuli Brullo, Lo Giudice & Privitera 1991 (Table VII) This association occurs on shady and consolidate soil covered by the shrubs in the ambit of the maquis with P. lentiscus, M. communis, Cistus sp. pl. dominant. It is a terricolous, xerophytic, preferably sciophytic community. In the investigated area, it is quite diffused. In Italy, it is known from Sicily, Sardinia and Central-Southern Italy.
Funarietum hygrometricae Engel 1949 (Table  VIII) It is a pioneer association typical of nitrified or burnt soils and thus indicated as a pyrophilous association. It was found only at Marina di Camerota on burned soil. Widespread in Central Europe, it is also reported from France, Spain, Morocco, S. Italy and Sicily.
Rhynchostegietum megapolitani Puglisi 1995 (Table IX)    This association, floristically very rich, is the most widespread in the investigated area. It was found on dry and very shade soil within the grassland with A. mauritanicus and the pinewood Pistacio-Pinetum halepensis. Ecologically, it is a terricolous, xerophytic, markedly sciophytic association. Rhynchostegietum megapolitani is included in the alliance Homalothecio aurei-Plurochaetion squarrosae (Ros & Guerra 1987) Marstaller 1993 of the order Pleurochaeto squarrosae-Abietinelletalia abietinae; this alliance groups communities with Mediterranean distribution and penetration up to the Atlantic coasts. The association is widespread in Southern Italy and Sicily.
Gongylanthetum ericetori Puglisi & Privitera ass. nov. (Holotypus: rel. 3) (Table X) On humid and shady soil covering rocky slopes of cliffs, in damp hollows on coastal heaths and on roadside banks near the sea, a spring community dominated by the Mediterranean-Atlantic liverwort Gongylanthus ericetorum was found. To this species Epipterygium tozeri, Cephaloziella turneri, Fossombronia angulosa, characteristics of the suballiance Fissidenti serrulati-Fossombronienion angulosae, besides Pleuridium acuminatum and Fissidens taxifolius ssp. taxifolius of the alliance Dicranellion heteromallae, are associated. A similar vegetation was found at Vulcano Island (Aeolian archipelago) in comparable ecological conditions, where it is reported as Gongylanthus ericetorum community ; the phytosociological relevés from Vulcano are also reported in Table X. Ecologically, it behaves as a terri-saxicolous, mesophytic, thermophytic, photophytic community. For its cover values and constant presence, Gongylanthus ericetorum is proposed as characteristic of the new association; this species is here signaled for the first time for the Campania region. Due to the floristic composition and due to the ecological features, this community is to place in the above mentioned syntaxa Fissidenti serrulati-Fossombronienion angulosae and Dicranellion heteromallae.
Schistidio apocarpi-Grimmietum pulvinatae Privitera & Puglisi 1996 (Table XI) A strictly saxicolous, photophytic, xerophytic association colonizing dry and sunny rocks in the clearings of garrigue with Cistus sp. pl. and Calicotome villosa at Contrada S. Gennaro and Piano Cupo. The association is known from Sicily and S. Italy.  (8) -    Syntrichietum laevipilae Ochsner 1928 (Table  XIII) This community was found on the middle and middle-higher parts of the trunks of isolated trees of Quercus ilex L. at Punta Infreschi and Olea europaea L. at Porto Palinuro. It is a corticolus, thermophytic, xerophytic association, quite widespread in Italy.

Leptodonto smithii-Leucodontetum sciuroidis
In the coastal area of PNCVD, short turf is the strongly prevalent life form in all the association belonging to the phytosociological class B. unguiculatae and in the association Syntrichietum laevipilae of the class Frullanio dilatate-Leucodontetea sciuroidis (Table XVI); this category is typical of the acrocarpous mosses and generally increases in xeric, sunny and often disturbed habitats. The life form cushion predominates in the saxicolous association Schistidio apocarpi-Grimmietum pulvinatae. The life form weft, occurring in all the associations, strongly prevails in Rhynchostegietum megapolitani, Rhynchostegielletum algirianae, Fabronietum pusillae, found in mesic and more sheltered habitats. The annual species, mostly represented by liverworts, prevail only in the association Gongylanthetum ericetori. Finally, the fan life form, attributes to Leptodon smithii, predominates in the association Leptodonto smithii-Leucodontetum sciuroidis.
Ratio St/We. This index was proposed by the authors taking into account the scale of tolerance to the air pollution of the life forms proposed by Gilbert (1970) and it was tested for the evaluation of the human impact in the ecosystems of the Mediterranean region (Privitera & Puglisi 2001;Guglielmo et al. 2003). The value of this index is directly proportional to the increase of human disturbance.
Life strategy. The environment provides the major selection pressure on the life cycle strategies. Taking into account the instability of the environment with its fluctuations, During (1979) considered that bryophytes utilize three major trade-offs: few large spores vs. many small spores, survival of stressful season as spores (avoidance) vs. survival as a gametophyte (tolerance), and life span that is negatively correlated with reproductive effort. In the investigated area, the life strategy colonist markedly prevails in the association of the alliances Grimaldion fragrantis and Tortellion flavovirentis (Table XVI). These species can be considered as pioneers colonizing hard environments; they appear in primary successional series and are important forerunners in soil accumulation and plant succession. They generally are found in dry habitats where the short life span, caused by drought-dependent mortality, is compensated by a high production of small spores. By contrast, the perennial stayers are of typical undisturbed stable environments and are most prominent in later successional series. They occupy habitats that are constant or where the fluctuations can be tolerated by the gametophytes. In the coastal area of PNCVD, the perennial stayers predominate in the epiphytic associations and in the association Rhynchostegietum megapolitani, a postpioneer association normally occurring on deep soil. The perennial shuttle species strategy combines desiccation tolerant gametophytes with large spores. This strategy is typical of unchanging and constant ecological conditions and long-lasting microsites in hardly disturbed sites where end of habitat is predictable. In the investigated area, these species are present in the epiphytic associations and prevail in the Gongylanthetum ericetori. The annual shuttle    (Table XVI). The species with a wide range (i.e. a-euhemerobous, oligo-euhemerobous, meso-polyhemerobous) were taken into account in the percentage calculation but omitted in the table.
This index, used for phanerogamic vegetation, is well applicable to bryophyte communities too.

Discussion
The results of this study have pointed out a great bryophyte vegetation diversity in the coastal area of the Cilento and Vallo di Diano National Park, reflecting the multiplicity and diversity of microand macro-habitats, part of a mosaic of ecosystems with a high landscape value.
The phytosociological investigation has emphasized the occurrence of 15 bryophyte associations (eight terricolous, three corticolous, two epilithic, and two terri-saxicolous), a number quite elevated for a Mediterranean costal area. Many associations belong to the class Barbuletea unguiculatae, including thermo-xerophytic communities some of which tolerant to human-induced disturbance.
Moreover, this investigation allowed the finding of the new association Gongylanthetum ericetori, a coastal Mediterranean community, belonging to the class Cladonio digitatae-Lepidozietea reptantis, characterized by the rare liverwort Gongylanthetum ericetori. Finally, within the surveyed associations some species rare and interesting from a phytogeographical point of view were found too; they are: Gongylanthus ericetorum, Calypogeia arguta, Fissidens gracilifolius, new records for Campania region, and the very rare Tortella flavovirens var. papillosissima, new record for peninsular Italy.
The analysis of the bryophyte vegetation, through the application of ecological and biological parameters, has revealed that the associations Barbuletum convolutae, Funarietum hygrometricae, Didymodonto vinealis-Tortuletum muralis can be considered markers of anthropogenic ecosystems; nevertheless, they are not common in the investigated area where they are confined to peculiar microsites.
On the contrary, Tortelletum papillosissimae, Tortello flavovirentis-Trichostometum crispuli, Rhynchostegielletum algirianae, and Rhynchostegietum megapolitani, widespread in the investigated areas, besides the corticolous associations (Syntrichietum laevipilae, Leptodonto-Leucodontetum sciuroidis, and Fabronietum pusillae), can be considered typical of semi-natural and poorly disturbed habitats. Therefore, the analysis of the bryophyte vegetation overall shows a rather good degree of naturalness and air purity of the coastal ecosystem of the PNCVD.
This investigation provides data showing the situation of a Mediterranean area with many natural communities and few aspects suggesting a certain anthropic disturbance mostly localized near the urban areas. The occurrence of many natural associations testifies the great importance of the Cilento and Vallo di Diano National Park as refuge and safeguard area for these associations of great naturalistic value.