A checklist of the exclusive vascular flora of Sardinia with priority rankings for conservation

Bacchetta, G., Fenu, G. & Mattana, E. 2012. A checklist of the exclusive vascular flora of Sardinia with priority rankings for conservation. Anales Jard. Bot. Madrid 69(1): 81-89. Sardinia is the second-largest island in the Mediterranean Sea and its isolation and high geological diversity have created a wide range of habitats with high levels of endemism, especially on its mountain massifs, where there are conditions of ecological insularity. In this study the exclusive endemic flora of Sardinia has been updated to 168 taxa, 139 of which are species, 23 subspecies, 4 varieties and 2 hybrids, belonging to 37 families and 72 genera. Despite this rich biodiversity and the threats to these species, few biological conservation studies have been carried out up to now. A conservation project for the most threatened exclusive endemic species of Sardinia was therefore funded in 2007 by the “Regione Autonoma della Sardegna”. To categorize these species of conservation interest, a priority list was created by applying 11 parameters based on rarity, threats and protection status. This work allowed the identification of the most threatened species of the Sardinian endemic flora.

Sardinia, situated in the Western Mediterranean basin, is the second largest island in the Mediterranean Sea (after Sicily).Its isolation and high geological diversity have created a wide range of habitats, with high levels of endemism, especially on its mountain massifs, where there are conditions of ecological insularity (Médail & Quézel, 1997).The Sardinian flora consists of 2,408 taxa, including 2,295 species (Conti & al., 2005), of which 347 are endemics (e.g.narrow endemics, Sardinian endemics, Corso-Sardinian endemics, Corso-Sardinian-Balearic endemics), with 45.8% being exclusive Sardinian endemics (Bacchetta & al., 2005).
About a hundred species endemic to Sardinia (Conti & al., 1992(Conti & al., , 1997;;Scoppola & Spampinato, 2005) have been recognized as threatened; furthermore, five exclusive endemics [i.e.Aquilegia barbaricina Arrigoni & E. Nardi, A. nuragica Arrigoni & E. Nardi, Lamyropsis microcephala (Moris) Dittrich & Greuter, Polygala sinisica Arrigoni and Ribes sardoum Martelli] have been included by the IUCN/SSC -Mediterranean Island Plant Specialist Group in the "Top 50 Mediterranean Island Plants" to be urgen tly conserved (Montmollin de & Strahm, 2005).Despite this rich biodiversity and the threats to these species, few biological conservation studies have been carried out in Sardinia (Fenu & Mattana, 2011).The level of threat to a species represents one of the most important parameters for the creation of target plant lists.The criteria established by the International Union for the Conservation of the Nature (IUCN, 2001) are widely employed as the gold standard for A checklist of the exclusive vascular flora of Sardinia with priority rankings for conservation Gianluigi Bacchetta*, Giuseppe Fenu & Efisio Mattana Centro Conservazione Biodiversità (CCB), Dipartimento di Scienze della Vita e dell'Ambiente, Università degli Studi di Cagliari, v.le Sant'Ignazio da Laconi, 13, 09123 Cagliari, Italy.bacchet@unica.itIslands) seems to be defined by their ecological specificity, geographical rarity and rate of threat.Jiménez-Alfaro & al. (2010), based on the results achieved in a study focused on the Cantabrian Range (Spain), suggested that different point-scoring procedures might have a high impact on the application of priority lists for selecting conservation targets.Gauthier & al. (2010), compared three criteria associated with rarity in the Languedoc-Roussillon region (France) with the aim of establishing regional-level priorities; they identified the "regional responsibility" (i.e.highest scores given to species whose distribution is endemic to the study area) as the first order of priority at local level.
In this context, a project, funded in 2007 by the "Regione Autonoma della Sardegna", was awarded to the University of Cagliari for the conservation of the most threatened endemic species of the Island.The exclusive endemic vascular flora of Sardinia and the priority list that were elaborated within the framework of this project are presented here.

MATERIAL AND METHODS
Floristic researches were undertaken throughout the Island between 2004 and 2010.During this period a number of excursions were made to study the different seasonal aspects.Specimens and seeds collected in the field were stored in the Herbarium CAG and in the Sardinian Germplasm Bank G. Bacchetta & al. information on the conservation status of species (e.g.Grammont de & Cuarón, 2006;Rodrigues & al., 2006;Hoffman & al., 2008).During the last decade, nature conservation in Europe has been focused on the implementation of the Habitat Directive (DIR.92/43/EEC) and the Natura 2000 network.Natura 2000 is by far the most important conservation effort implemented in Europe (Maiorano & al., 2007) and it was proposed as the main strategy to meet the target of halting (or at least significantly reducing) biodiversity loss by 2010 (Balmford & al., 2005).Its main goal is either to maintain or restore a 'favorable' conservation status for species and habitat types of special importance.
In the Mediterranean area, plant conservation prioritysettings at finer-scales (i.e.biogeographical province, see Bacchetta & al., 2011b) should be preferred due to biogeographic and cultural diversity and regional threats (Médail & Quezel, 1999).Moreover, when working in such speciesrich areas, "priority lists" should be created in order to identify the target species for conservation measures, since biodiversity conservation policies have to operate with only limited resources (Balmford & al., 2005).
A priority list was created by integrating the three kinds of lists reported in Grammont de & Cuarón ( 2006): (1) lists based on the degree of biological threat, (2) conservation lists and (3) international and national protection catalogues.The establishment of the criteria for conservation priorities, and the evaluation and selection of the target taxa were based on the analysis of 11 parameters (Table 1), and the final score was determined by summing the values calculated for each parameter; data were obtained from the literature, from herbarium specimens and field surveys.To determine the protection status, extra values were attributed to those taxa inserted in international and national protection catalogues.In particular, the Annexe II of the European Directive "Habitat", the Italian national (Conti & al., 1992) and regional (Conti & al., 1997) Red Lists, as updated by Pignatti & al. (2001) and Scoppola & Spampinato (2005), the IUCN Red list (IUCN, 2010) and the IUCN Top50 species of the Mediterranean islands (Montmollin de & Strahm, 2005) were consulted (Table 1).The adopted taxonomic nomenclature followed the Annotated Checklist of the Italian Vascular Flora (Conti & al., 2005).
Nine exclusive endemics are included in the Annex II of the Habitat Directive and 8 of these are considered as priority species (Astragalus maritimus and A. verrucosus, Centaurea  with a centre of diversification in the Mediterranean basin, where several hundred endemic species occur (Rosselló & Castro, 2008).In Sardinia 38 species have been recognized (Arrigoni & Diana, 1999).The Tyrrhenian area also represents a speciation centre for many plant groups associated with Tertiary floras, such as the Genista ephedroides group (Bacchetta & al., 2011a), which explains the high number of Genista species that are exclusive endemics to the Island.Sardinia is also a major centre of diversity and endemism for the genus Anchusa, with six allopatric taxa occurring in either coastal or mountain habitats of the island (Bacchetta & al., 2008).The genus Ophrys has extensively radiated throughout the Mediterranean region (Delforge, 2006) and now encompasses more than 200 species (Gögler & al., 2009).The number of endemic species belonging to this genus is a consequence of the high number of taxa that were described mainly in the last 30 years (Delforge, 2006), as a consequence of the difficulties of classifying Ophrys taxa into a consensual taxonomic system (Gögler & al., 2009).
The high percentages of chamaephytes and hemicryptophytes detected in this study highlight the pivotal role of the ecological insularity of the mountain massifs for the differentiation of the Sardinian endemic flora (Médail & Quézel, 1997), as confirmed by previous studies (Bacchetta & Pontecorvo, 2005;Bacchetta, 2006).In particular, the antiquity of the limestone mountains and the high incidence of cliffs, have promoted a long evolutionary process in the flora of the Island that has given rise to many specialized chasmophytes (Bacchetta & al., 2007), as previously reported by Fenu & al. (2010) for the Supramontes region.Many of these taxa are narrow endemics and most of them make the endemic flora of the Sardinian mountains distinguishable from that of Corsica (Arrigoni, 1983).
The conservation priority ranking allowed the identification of the ten most threatened species, and an integrated conservation approach was initiated for them thanks to the G. Bacchetta & al.Regarding the conservation priorities, it was possible to assign a score on the basis of the considered parameters for all the species, with the exception of Centaurea forsythiana, Limonium multifurcatum, Medicago intertexta var.tuberculata, Ophrys scolopax subsp.sardoa, Senecio siculus var.nemoralis and Senecio vulgaris var.tyrrhenus, for which data were deficient (see Appendix).The ten most threatened species are reported in Table 2, with scores ranging from 33 for Astragalus maritimus and A. verrucosus to a maxi mum of 41 for Ribes sardoum, which is therefore the most threatened Sardinian endemic according to our results.All these species are catalogued in the official IUCN Red List (IUCN, 2010) with the exception of Anchusa litto rea, Dianthus morisianus, Astragalus maritimus and A. verrucosus, for which IUCN categories have been proposed by different authors (see Fenu & Bacchetta, 2008;Fenu & al., 2010;Bacchetta & al., 2011c).All these species are conside red, or have been proposed for consideration, under the Critically Endangered (CR) category.

DISCUSSION
This work allowed the production of an exhaustive checklist of the exclusive endemic vascular flora of Sardinia, thus updating the previous works in which the endemic component of the Island was analyzed (Bacchetta & al., 2005;Conti & al., 2005).
The percentage of exclusive taxa of Sardinia (6.9%) is similar to that of Corsica (6.3%), thus providing further evidence for the floristic autonomy of the Corso-Sardinian flora, due to their geographical and ecological isolation (Médail & Quézel, 1997;Mansion & al., 2008).The preponderance of species belonging to the family Plumbaginaceae was mainly due to the high number of Limonium species endemic to the Island.Limonium is a taxonomically complex group, mainly comprising sexual and apomictic perennial herbs and sub-shrubs that are distributed worldwide but  (Bacchetta & al., 2011c) The exclusive flora of Sardinia project funded in 2007 and renewed in 2009 by the "Regione Autonoma della Sardegna".In particular, their populations have been characterized, and long-term conservation measures were carried out by seed collections that are maintained at the Sardinian Germplasm Bank (BG-SAR).Furthermore, ecological (Bacchetta & al., 2011c;Fenu & al., 2010Fenu & al., , 2011Fenu & al., , 2012)), ecophysiology of seed germination (Cogoni & al., 2012;Mattana & al., 2009Mattana & al., , 2010aMattana & al., , b, 2012)), as well as population genetic studies (Garrido & al., 2012;Bacchetta & al., data unpublished) have been undertaken with these taxa.
In conclusion, the rankings established here provide an updated useful tool at the regional scale for the implementation of in situ and ex situ conservation measures, according to the criterion of "regional responsibility" elaborated by Gauthier & al. (2010).

Fig. 1 .
Fig. 1.The most represented families of the exclusive vascular flora of Sardinia.

Fig. 2 .
Fig. 2. The most represented genera of the exclusive vascular flora of Sardinia.

Table 1 .
Parameters used to calculate the Priority list.

Table 2 .
The ten most threatened exclusive endemic species of Sardinia.