Lathyro asphodeloidis-Klaseetum lycopifoliae , a new plant association in the alliance Cynosurion cristati Tüxen , 1947 in Central Apennines

This study presents a new plant association discovered in the Central Apennines and named Lathyro asphodeloidis-Klaseetum lycopifoliae. It consists of a semi-natural meadow characterized by the co-dominance of two rare taxa, Klasea lycopifolia and Lathyrus pannonicus subsp. asphodeloides, occurring in Italy in only a few localities in the Central and Northen Apennines. The association was discovered on the Altopiano delle Rocche high plateau in the province of L’Aquila (Abruzzo region, Italy). Multivariate analysis of the relevés shows two floristic and ecological aspects, corresponding to two different subassociations: festucetosum circummediterraneae, with elements from the Festuco-Brometea class, growing in the outer portions of the plateau, and narcissetosum poëtici, corresponding to the most typical aspect and occupying the central part of the plateau, differentiated by meso-hygrophilous species of the Molinietalia and Trifolio-Hordeetalia orders. The plant association has great natural value, due to the presence of several rare plant species, and cultural importance in association with the traditional “Narcissus Fest” held each year in May.

This study presents a new type of humid meadow, with a physiognomy characterized by the dominance of Klasea lycopifolia (Vill.)Á.Löve & D.Löve, a very rare member of the Asteraceae family with a W-C-Pontic SE-Sarmatic distribution and Pannonic, W-Illyrian and W-Alpine disjunct populations (Conti and Manzi 1997).Very rare throughout Italy, the species is present in just nine sites in Abruzzo, Emilia-Romagna, Umbria and Marche (Gigante et al. 2014).It was indicated for the first time in Italy in the Sirente-Velino Regional Park where it is present in four different sites (Conti and Manzi 1997;Ciaschetti 2003;De Santis and Soldati 2011).
Included among the endangered species on the Italian Red List (Rossi et al. 2013) and as a priority species in Annex II of the Habitat Directive, Klasea lycopifolia (Vill.)Á.Löve & D.Löve is the subject of a Life project aimed at safeguarding and valorizing seven species of European interest in three national parks in the Central Apennines (Di Martino et al. 2016).
Lathyrus pannonicus (Jacq.)Garcke subsp.asphodeloides (Gouan) Bässler, a rare sub-species with a South-European distribution, is abundant in the studied vegetation.In Italy it is present only in Lazio, Abruzzo and Molise, while it is doubtful in Basilicata and Calabria (Bartolucci et al. 2018c).

Study area
The study area (Suppl.material 1: 1) corresponds to the Altopiano delle Rocche high plateau in the Sirente-Velino Regional Nature Park, L'Aquila province, Abruzzo region.In particular, the study considers the northernmost part of the high plateau, between the villages of Rocca di Mezzo, Rocca di Cambio and Terranera (42°13.85'N,13°31.05'E).This consists of a vast "polje" type plain of tectonic-karst origin, once site of an ancient lacustrine basin, at a mean altitude of 1350 a.m.s.l.It is bordered to the north and west by Monte Cagno (2153 m a.m.s.l.), Forcamiccia (1909 m a.m.s.l.) and Monte Rotondo (2060 m a.m.s.l.), and to the east by a series of lower elevations including the Monti della Cerreta (1510 m a.m.s.l.), Colle Jannini (1432 m a.m.s.l.) and Monte Grilletti (1361 m a.m.s.l.), separating it from the Subequana Valley.
To the south, the high plateau extends beyond the village of Rocca di Mezzo as far as Ovindoli and the Arano Valley.
The majority of the plateau is occupied by Holocene lacustrine sediments overlaid by deep sometimes hydromorphic soils with an A-B-C-profile, with fine to moderately fine texture, almost no stony surface cover and a low skeleton content, generally decarbonated and with a slightly acid surface reaction, gradually progressing to neutral with depth (Vannicelli Casoni 1999).
To classify the climate, thirty years of data from the nearby precipitation and temperature station of Rocca di Mezzo (1329 a.m.s.l.) were analysed and used to construct the ombrothermic diagram (Suppl.material 1: 2).Analysis of the data showed the winter cold to be a significant characteristic of the area, with minimum temperatures below 0 °C for five months and mean temperatures below 10 °C for seven months.There is no summer aridity and near semi-arid conditions as defined by Rivas-Martínez (2011), i.e.P ≤ 2.5T, occur only in July.According to the Rivas-Martínez bioclimatic classification (2011), the area can be classified in the sub-Mediterranean variant of the oceanic temperate bioclimate, upper supra-temperate thermotype, upper humid ombrotype.
The vegetation of the study area is mowed once a year, usually at the end of July, and only occasionally it is grazed by a few animals after mowing.For details on management and its implications on flora composition, see Giallonardo et al. (2019).

Material and methods
The vegetation under study was analysed using the classical phytosociological method of the Zurich-Montpellier sigmatist school (Braun-Blanquet 1964).The abundancedominance indices were transformed by numerical processing according to the scale proposed by Van der Maarel (1979).The matrix of 77 species × 15 relevés thus obtained was cleaned of the companion species present in just one relevé and then processed using the multivariate analysis techniques in the SYNTAX-2000 package (Podani 2001).In particular, cluster analysis was performed using the chord distance as

Sporadic species
the correlation coefficient and average linkage as the clustering strategy.Several ordinations (PCA, PCoA, NMDS) were carried out to confirm the validity and separation of the clusters identified.
A further PCoA was performed on the synoptic table built with the original tables of all the associations attributed by Blasi et al. (2012) to the suballiance Cerastio arvensis-Cynosurenion, plus the table presented here.The chord distance was used as dissimilarity coefficient.
The nomenclature follows the updated checklist of the vascular flora native to Italy (Bartolucci et al. 2018a(Bartolucci et al. , 2018b(Bartolucci et al. , 2018c)), while the syntaxonomic classification follows the Prodrome of Italian Vegetation (Biondi et al. 2014).
The diagnostic species of the classes in Table 1 follow Mucina et al. (2016), with the exception of Tulipa pumila Moench (Aeschimann et al. 2004) and Euphorbia gasparrini Boiss.subsp.samnitica (Fiori) Pignatti (no data available, our own interpretation).For species in the Cynosurion alliance and Trifolio-Phleetalia order, reference was made to the Italian Vegetation Prodrome (Biondi et al. 2014).

Results
The studied vegetation is to be framed in the Cynosurion cristati alliance, as shown in Table 1.Regarding to the two sub-alliances identified in Central Italy (Blasi et al. 2012), the geographical, environmental and floristic features of this vegetation, together with the low presence of annual and Mediterranean species, led us to refer it to the Cerastio arvensis-Cynosurenion sub-alliance described for Central-Northen Apennines (Blasi et al. 2012).
The PCoA performed on the synoptic table built with all the associations attributed by Blasi et al. (2012) to this sub-alliance highlights the autonomy of the studied vegetation by putting it in a clearly separate space with respect to the others (Suppl.material 1: 3).
The hierarchical classification of the relevés (Suppl.material 1: 4) clearly highlights the distinction of two clusters within the described vegetation, also confirmed by several ordinations performed (PCA, PCoA, NMDS) but not presented here.
Even if the framing of the studied vegetation is to be in the Cynosurion alliance and in the Cerastio arvensis-Cynosurenion sub-alliance, this vegetation does not spread far from the altitudinal and ecological limits of the alliance, with some affinities with the communities of the Ranunculion velutini alliance with which it is in topographical contact (Suppl.material 1: 5).
The studied vegetation also differs considerably from those described for the nearby Piano di Pezza (Ciaschetti et al. 2006) which is located at a higher altitude and only grazed.
All these differences led us to propose a new association with the name of Lathyro asphodeloidis-Klaseetum lycopifoliae (typus rel.12, Table 1) in the Cynosurion cristati alliance.At suballiance level, it is to be classified in the Cerastio arvensis-Cynosurenion cristati suballiance described by Blasi et al. (2012) for the Central-Northern Apennines.
Consisting of four relevés, the cluster I of the dendrogram (Suppl.material 1: 4) refers to the more xeric aspects of the association prevailing in the outermost areas of the plain characterized by lower edaphic humidity.These aspects are differentiated by a contingent of species characteristic of xeric and semi-mesophilous secondary pastures of the Festuco-Brometea class, such as Festuca circummediterranea Patzke, Poa bulbosa L. subsp.bulbosa, Astragalus danicus Retz., Podospermum canum C.A.Mey., Medicago lupulina L., Veronica orsiniana Ten. and Bromopsis erecta (Huds.)Fourr.subsp.erecta.This group of relevés corresponds to the subassociation festucetosum circummediterraneae (typus: rel. 1, Table 1).
The position of the two subassociations along a sequence following a water-soil gradient in the plateau is shown in suppl.material 1: 5.
The new association shows a particular floristic composition with the low presence or absence of some characteristic species of the Cynosurion alliance, such as Lolium perenne L., Phleum pratense L. subsp.pratense, Phleum nodosum L., Scorzoneroides autumnalis (L.) Moench and Veronica serpyllifolia L. On the other hand, probably due to less disturbance by grazing cattle, it includes several rare species, making this vegetation important from a conservation point of view: Klasea lycopifolia (Vill.)Á.Löve & D.Löve [= Serratula lycopifolia (Vill.) A. Kern.]In Italy, according to Gigante et al. (2014) and Bartolucci et al. (2018c) this species occurs in Emilia-Romagna, Umbria, Marche and Abruzzo.In the latter region, it is indicated for the localities of Le Prata and Campo di Rovere on the Altopiano delle Rocche (Conti and Manzi 1997;Ciaschetti 2003), Prati del Sirente (Ciaschetti 2003) andCampo Felice (De Santis andSoldati 2011).It is listed as a priority species in Annex II of the Habitat Directive and included in Category 1 (Extremely rare or endangered species, or species with a very small population, exclusive or at the limit of their distribution area and known for few point localities) in Conti and Bartolucci (2012).
It is listed as a priority species in Annex II of the Habitat Directive, indicated as Vulnerable (VU) in the Regional Red List of Endangered Flora (Conti et al. 1997) and included in Category 1 (Extremely rare or endangered species, or species with a very small population, exclusive or at the limit of their distribution area and known for few point localities) in the List of Plants of Conservation Interest in Abruzzo (Conti and Bartolucci 2012).
It is protected by the Regional Law for the Protection of Spontaneous Flora (Abruzzo Regional Laws 45/79 and 66/80) and is included as a species at low risk (LR) in the Regional Red List of Endangered Flora (Conti et al. 1997).
According to the IUCN criteria, is evaluated as Least Concern (LC; Orsenigo et al. 2018) and included in Category 2 (Endemic but not endangered species) in the List of Plants of Conservation Interest in Abruzzo (Conti and Bartolucci 2012).

Ranunculus marsicus Guss. & Ten.
Species endemic to the Central Apennines, occurring from the Gran Sasso massif to the Monti della Meta (Dunkel 2011).
It is evaluated as Data Deficient (DD; Orsenigo et al. 2018) and included in Category 0 (Extremely rare or endangered species, or species with a very small population, exclusive or at the limit of their distribution area and known for few point localities) in the List of Plants of Conservation Interest in Abruzzo (Conti and Bartolucci 2012).
Tulipa pumila Moench (= T. australis Link) Species with a Mediterranean-montane distribution (Pignatti 2017), very rare in Abruzzo where it is indicated for the Piano di Ovindoli (Pignatti 1982) and the Collelongo area (Conti and Bartolucci 2015).It is included in Category 1 (Extremely rare or endangered species, or species with a very small population, exclusive or at the limit of their distribution area and known for few point localities) in the List of Plants of Conservation Interest in Abruzzo (Conti and Bartolucci 2012).Sanguisorba officinalis L. Species quite rare in Abruzzo, indicated for a number of localities (Mauri et al. 1830;Tenore and Gussone 1842;Tammaro 1986, Pirone 1987a;Guarrera and Tammaro 1994;Buchwald 1995;Conti 1998).It is included in Category 3 (Rare or exclusive species, or species at the limit of their distribution area, not endangered, but sometimes in decline) in the List of Plants of Conservation Interest in Abruzzo (Conti and Bartolucci 2012).
The species is indicated as Vulnerable (VU) in the Regional Red List of Endangered Flora (Conti et al. 1997).

Conclusions
Phytosociological analysis of the meadow vegetation of the Altopiano delle Rocche high plateau led to identification of a new association, Lathyro asphodeloidis-Klaseetum lycopifoliae, currently known to be present exclusively between Rocca di Mezzo, Rocca di Cambio and Terranera on the Altopiano delle Rocche.With its own distinct floristic identity with respect to the other Cynosurion formations described, including at physiognomic level, the association has high biogeographic and conservation value for the presence of a number of species rare in Abruzzo and/or in Italy as a whole, above all in the narcissetosum poëtici subassociation, relating to the most widespread aspect occurring in the Le Prata area.
It is therefore to be hoped that in the future, the area, included in the Sirente-Velino Regional Park, will not be subjected to environmental disturbance or variations in forms of use which could compromise its conservation, and that, in addition to the LIFE project FLORANET (Di Martino et al. 2016) currently underway, the Park Authority implements the due monitoring measures in order to assess possible modifications over time in the extension and floristic composition of this very particular and unique plant community.