Contribution to the knowledge of the Bryophyte Flora of the Vatican City State : The Pontifical Villas of Castel Gandolfo

Aleffi, M.: Contribution to the knowledge of the Bryophyte Flora of the Vatican City State: The Pontifical Villas of Castel Gandolfo (Rome, Italy). — Fl. Medit. 27: 137-150. 2017. — ISSN: 1120-4052 printed, 2240-4538 online. For the first time, the bryoflora of the Pontifical Villas of Castel Gandolfo (Vatican City State) has been studied. Research led to the identification of 87 bryophytes (1 hornworts, 15 liverworts and 71 mosses), among which one liverwort and six moss species are new reports for the Lazio Region. Zygodon forsteri, epiphyte species considered Vulnerable in Europe, Anthoceros agrestis and other species rare for Italy, were found in the study area. In addition, the life-form of each species was taken into consideration, in order to compare with the ecological and climatic characteristics of the territory examined. The study contributes to the knowledge of a territory of the Vatican City State that until now had been almost unexplored from the bryological point of view and provides important information for the realization and definition of the European and Mediterranean Red List of Bryophytes.


Introduction
This work, conducted in the Pontifical Villas of Castel Gandolfo, completes the research carried out on the bryological flora of the Vatican Gardens (Aleffi 2015), providing more detailed information for the production of the Check-List and country status of European Bryophytes.
Previously, numerous studies of the vascular and cryptogamic flora of the city of Rome have been carried out but they did not include this small country.The information about bryophytes in Vatican City was provided only by Bizot (1965) who collected some species from the Dome of Saint Peter's Basilica, and recently by Aleffi (2015), who identified 121 taxa mostly concentrated in the Vatican Gardens.

Study area
The Pontifical Villas of Castel Gandolfo comprise about 55 hectares: 30 ha make up a garden, while 25 ha are used for farming.The latter is carried out with full regard for the aesthetics proper to countryside gardening.The Pontifical Villas complex includes the Papal Palace, the Barberini Palace and Villa Cybo, and extends from the top of the hill of Castel Gandolfo (41°44'48.65"N -12°38'56.79"E), where the Papal Palace is located, as far as the residential area of Albano (41°43'53.21"N -12°39'30.34"E), along the southwestern edge of the crater that forms Lake Albano, in a dominating position facing the Tyrrhenian Sea, at an altitude between 400 m and 450 m a.s.l.
The Pontifical Villas were built on the ruins of the central part of the summer residence of the Emperor Domitian (81-96 AD), which covered about 14 km 2 from the Appian Way to the shores of Lake Albano.After the death of Domitian, the imperial villa quickly began to deteriorate.It was only in July 1596, under the pontificate of Clement VIII, that the Apostolic Chamber took possession of the villas.Pope Clement XIV further enlarged the palace in March 1773 by acquiring the adjacent Villa Cybo.The Pontifical Villas took on their current dimensions after the Lateran Pacts of 1929, with the acquisition of the Villa Barberini complex, where gardens of a new design were established.Worthy of particular mention among these gardens is the Belvedere Garden.Pius XI completed the residence with the acquisition of some gardens toward Albano to create a farm (Fig. 1).
The area of the Pontifical Villas is part of the Roman Castles, an area of volcanic nature that originated with the collapse of the Latium Volcano several hundreds of thousands of years ago.The main opening of the Latium Volcano occupied the entire area of the inner belt of the Castles: its subsequent collapse gave rise to various secondary openings, the most important of which is the current Mont Cavo (949 m a.s.l.).The other minor openings of the Volcano became lacustrine basins during the hydromagmatic phase of the Latium Volcano through the encounter between magma and subsoil water between 100,000 and 20,000 years ago, the most important of which are Lake Albano and Lake Nemi; most of the other basins have been drained over the course of the centuries (Funiciello & Parotto 1978;Giordano & al. 2006).
According to the classification data of the National Geological Service (1961), most of the territory of the Roman Castles is composed of material from the final eruptions, which gave rise to the famous peperino, a material widely used in the construction of many buildings, including all of the Pontifical Villas.
From the climatic point of view, according to the classification of the ecoregions of Italy (Blasi & al. 2014), the studied area is part of the Mediterranean Division (Northern and Central Tyrrhenian Section of the Tyrrhenian Province) with mild winters, autumn temperatures higher than the spring ones, and breezy summers.Average annual precipitation is around 900-1000 mm with a reduction from January-February to July-August and a sharp increase in September.
The Alban Hills are marked by a phenomenon called the stau: the water vapor diminishes as the land elevation increases.Thus the greatest rainfall occurs on the first highlands of the Alban Hills, facing the Sea.Normally the area is subject to winds from the southwest, namely the scirocco and libeccio.Instead, during the winter there are the strong cool winds from the north and northeast, the tramontana and grecale winds.
The sub-Mediterranean climatic conditions, which fall between the strictly Mediterranean and Temperate ones, and are determined by a moderate drought in the summer period (Blasi & al. 1999;Blasi & Michetti 2005), influence the cryptogamic flora.

Material and Methods
The research was conducted between September 2014 and May 2015 in several phases.The first examined the entire area of the Pontifical Villas, while the later ones concentrated on areas with microclimatic and floristic characteristics of greater bryological interest, such as tree trunks (Fig. 2), archaeological sites and flowerbed soils where there is persistent humidity, with particular regard to the following sites: the Avenue of Holm Oaks which is adjacent to the entrance of Villa Barberini and reaches the square bordered by the Roman Amphitheatre; an analogous avenue, formed of centuries-old holm oaks, is located between the olive grove of the farm and the Belvedere gardens; Domitians's Amphitheatre: built on the pre-existing structures of the Villa of Domitian (81-96 A.D.), characterized by a series of steps originally covered with polychrome marble, and by a theatre building in packed earth; the Avenue of the Nympheums: starting from the Amphitheatre, currently form the backdrop for the centuries-old trees that compose the Italian-style garden; Belvedere Gardens: divided into three parterres, the historic gardens are the heart of Villa Barberini, and extend beyond the 300 meters of length of the cryptoporticus that runs alongside them; the gardens are bordered by an avenue of aromatic herbs where numerous officinal plants are cultivated (Fig. 3).
The following list of bryophytes collected during this research gives each taxon in alphabetical order, with the location and environment where it was collected.Nomenclature follows Ros & al. (2007) for liverworts and Ros & al. (2013) for mosses.The chorotypes and  the ecological features are drawn from Dierβen (2001); the life forms from Hill & al. (2007).The samples are kept in the Herbarium of University of Camerino (CAME).
The new taxa for the Lazio Region (the geographic region within which the Castel Gandolfo Villas are located) are marked with asterisk (*).

Results
The research conducted in the Pontifical Villas of Castel Gandolfo identified 87 bryophytes: 1 hornwort, 15 liverworts and 71 mosses (Table 1).Of these, 1 hornwort, 4 liverworts and 23 mosses are additions to the bryoflora of the Vatican City State (Aleffi 2015).According to Aleffi & al. (2008), one liverwort and seven mosses are new records for the Lazio Region.
Another interesting finding is Cynodontium bruntonii.This species was reported for the regions of northern Italy and for Sicily (Blockeel 1995;Privitera & Puglisi 1996, 2002) and Sardinia (Aleffi & al. 1995;Frahm & al. 2008) and this is the only report for continental south-central Italy.It is a suboceanic-montane species that grows on siliceous rocks, with known locations in Europe, North Africa and Macaronesia (Dierβen 2001).
Zygodon forsteri in Italy was recently recorded only in the Marche (Aleffi & al. 2005), Campania (Cipollaro & Colacino 2005), Sicily (Dia & Lo Re 2005) and Sardinia (Frahm & al. 2008).It is an oceanic-submediterranean taxon distributed in the European continent in Bulgaria, Croatia, France, Greece, Montenegro, Portugal, Serbia, Spain, and Turkey; outside Europe it is present in Cyprus, Israel, Madeira and Syria (Ros & al. 2013).The species grows on the trunks and exposed roots, in well-lighted sites and in conditions of moderate moisture.It is considered Vulnerable (V) in Europe (ECCB 1995); in the United Kingdom it has been included in the "UK Biodiversity Action Plan" and in the "English Nature's Species Recovery Programme" with the purpose of conservation and increase of the populations in situ.Though the pattern of distribution of this species is on the whole fairly widespread, in fact its presence is limited to only a few locations with very small populations.
The bryoflora of the Pontifical Villas of Castel Gandolfo is characterized by the presence of a substantial number of species with Oceanic-Mediterranean tendency, which are about 50% of the species collected in the study area, against 35% of temperate species and a nonetheless significant 15% of species with boreal tendency.This fact is doubtlessly related to the particular ecological and microclimatic conditions in the Pontifical Villas, due to diversity of habitats and the permanent conditions of humidity present in the entire area.Concerning the substratum, the volcanic nature of the entire territory causes conditions of marked acidity, both in the soil and in the outcropping rocks.This has a decisive influence on the composition of the species, about half of which are acidophilous and 35% subneutrophilous species, while typically basiphilous species are only 15% of the total species observed (Dierβen 2001).
The particular structure of the Pontifical Villas, characterized not only by traditional Italianstyle gardens, but also by a fairly extensive area of farmland (olive groves, vineyards, fruit groves) and the substantial presence of archaeological ruins of the ancient Villa of Domitian (Amphitheatre, nymphaeums, etc.) have a significant influence on the bryophyte diversity and richness.Therefore, the bryophyte biodiversity of the Pontifical Villas is numerically high when compared with the data emerged from similar studies conducted in the gardens and parks of the urban area of Rome (Carcano 1989) and in some cities of Sicily (Dia & al. 2003).
Considering the area of the Vatican Gardens, which covers about 44 hectares, and that of the gardens of the Pontifical Villas of Castel Gandolfo, which extends for about 55 hectares, the study of the bryoflora of the territory of the Vatican City State covers about 100 hectares.Taken together, the two studies noted 149 taxa which are about 12.5% of the Italian flora, a significant percentage if one considers the modest extension of the territory studied.Of these, 1 hornworts, 1 liverworts and 16 mosses are new records for the Lazio Region.
On the basis of the substratum most of the species were collected on rocks (87 species), followed by terricolous species (57 species), while the epiphytes are 40.Most of the latter are species that grow exclusively on the bark of trees, such as Fabronia pusilla, Habrodon perpusillus, Nogopterium gracile and the species of the Orthotrichum genus.
The study of the bryoflora of the Vatican City State contributes significantly to the knowledge of a territory which until now had been scarcely explored from the bryological point of view, and provides important floristic information for the realization and definition of the Checklist and country status of European Bryophytes (Rossi & al. 2014;Sérgio & al. 2014;Hodgetts 2015).

Fig. 1 .
Fig. 1.The extensive area of farmland planted with olive trees is characterized by an interesting bryoflora.

Fig. 2 .
Fig.2.The holm oaks gallery presents special moisture conditions that favor the growth of bryophytes on tree trunks and rocks.

Fig. 3 .
Fig. 3.The Belvedere Gardens is the traditional Italian garden: the first level reproduces the design of a coffered ceiling.