A new winter deciduous forest and its associated Eurosiberian flora and vegetation in a Mediterranean mountain climatic refuge (Sierra Nevada, Spain)

Study area

The study area (Figure 1) corresponds to the northern face of Sierra Nevada, upper basin of the Alhama river in the province of Granada, in the south of the Iberian Peninsula (Andalusia, Spain). The area is included in the municipality of Lugros and to a lesser extent (the highest part) in the municipalities of Jerez del Marquesado and Güejar-Sierra. It is included in the Sierra Nevada National Park and in the Special Area of Conservation (SAC) with Site code ES6140009. It occupies a total of 20.79 km² state-owned land of which about 150 ha correspond to the Reserve Zone (21.4%). Altitudes reach between 1350 and 3088 m in the highest peak) above sea level. The lithology comprises a continuum of rocks derived from quartzite and micaschist (Martín et al., 2008; IGME, 2019), and the soils correspond to eutric and dystric cambisols (Balsera, 1989; FAO, 2009; Martín-Peinado et al., 2019).

Figure 1:

Based on the available data collected at the two meteorological stations present in the study area, bioclimatic parameters and indexes were calculated (Table 1). In addition, the Submediterraneity Index (Rivas-Martínez et al., 2011b) was determined for the two stations mentioned above (Table 2). The Embarcadero station at 1517 m obtained a sub-Mediterranean index (Isbm) of 0 (all Ios values were negative) which is interpreted as a water deficit extending throughout the summer season, i.e. zero sub-Mediterraneanity, and therefore a genuine Mediterranean climate with intense summer drought. For the Piedra de los Soldados station at 2155 m, all Ios reached negative values except in September (Ios4 = +0.71), which was decisive in the Isbm value of + 0.71. This resulted in very weak sub-Mediterraneanity, insufficient as a water supply to compensate for the central months of summer.

Bioclimatic diagrams have also been represented from the data of the two meteorological stations (Figure 2a, Figure 2b), showing a dry period coinciding with the summer months, generally from mid-late May to the end-middle of September, more accentuated at medium altitudes (1517 m) than at higher altitudes (2155 m).

Figure 2a:

Figure 2b:

The bioclimatic indexes, based on the bioclimatic classification of Rivas-Martínez (1996–2009) and Rivas-Martínez et al. (2017) were calculated for the two meteorological stations present at the study site:

Embarcadero station (1517 m): the site was classified as belonging to the lower supramediterranean thermotype (Mean annual temperature, T=12.38 ºC; Compensated thermal index, Itc=219) and the lower subhumid ombrotype (Average annual rainfall, P=540.15 mm; Annual ombrothermic index, Io=4.89).

Piedra de los Soldados station (2155 m): the site was classified as belonging to the lower oromediterranean thermotype (Mean annual temperature, T=7.94 ºC; Compensated thermal index, Itc=82.04) and the lower subhumid ombrotype (Average annual rainfall, P=477.01 mm; Annual ombrothermic index; Io=4.60).

Biogeographically, the area is classified into the Hol-arctic Kingdom, Mediterranean Region, Western Mediterranean Subregion, Iberian-Moroccan-Atlantic Super-province, Baetic Province, Nevadensian Sector and Nevadensian Subsector (Galán de Mera et al., 2003; Marfil et al., 2016).

Floristic study

The collection of plant specimens was done between August 2018 and July 2023 in the three main parts of the study area (Figure 2: low area -Horcajo de Camarate and Zona de Reserva Baja-, middle area -Arroyo de las Rozas and Tentadero- and high area -Zona de Reserva Alta and northern slope of Pico Mirador Bajo/Mirador Alto and Picón de Jeres). The samplings were carried out in two periods: spring-summer, and autumn, coinciding with the phenological development of flora and vegetation, and following altitudinal transects from 1350 m to 3088 m. All the possible ecosystems and micro-ecosystems (e.g. peat bogs) and altitudinal belts were visited. The works “Flora Vascular de Andalucía Oriental” (Blanca et al., 2011) and “Flora iberica” (Castroviejo et al., 1986–2021) have been used for the identification of vascular flora. Because of their importance, some bryophytes were also collected both in deciduous forests and in plant communities where they could be characteristic taxa (e–. hydrophytic vegetation). Identification has been made following Flora Briofitica Iberica (Guerra et al., 2006–2018) by the University of Murcia personnel (Dr. J. Guerra).

Taxa from GBIF.org recorded in the study area were also included. In order to determine the degree of threat for the catalogued flora, we have consulted the Spanish and Andalusian red books (Blanca et al., 1999, 2000; Bañares et al., 2004, 2010), the Spanish red list (Moreno, 2008) and the Andalusian red list (Cabezudo et al., 2005). The legal protection status of the catalogued species was included according to the Andalusian legislation (D 23/2012). For legally protected species we indicated: scientific name, family, protection status (according to Andalusian catalogue and list of wild species under special protection)(D 23/2012); PEC: Plant species of European Community interest in need of strict protection), threat degree in Red Lists of Spain -RLS- and/or Andalusia -RLA-; (Blanca et al., 1999, 2000; Bañares et al., 2004; Bañares et al., 2010; Moreno, 2008), ecology (Blanca et al., 2011), phytosociological class in the study site (Rivas-Martínez et al., 2011a), local endemism (Blanca et al., 2011) and for invasive alien species, Royal Decree 630/2013 and Sanz-Elorza et al. (2004) have been followed. Voucher specimens are deposited in the MGC Herbarium (University of Málaga) (Thiers, continuously updated).

For those taxa of greatest relevance, the percentages of threatened, protected and endemic flora were calculated based on the catalogue of flora collected, inventoried and initially cited in the databases GBIF (2023).

Vegetation study

For the description of the vegetation units, we applied the phytosociological methodology of Braun-Blanquet (1979), complemented by Gehú & Rivas-Martínez (1981) and Schuhwerk (1990). The most interesting forest vegetation for this study, such as winter-deciduous and marcescent forests, as well as their dynamic stages and catenal contact vegetation, have been inventoried. Phytosociological relevés (75) have been carried out between August 2018 and July 2023 in ecologically homogeneous plots, geo-referenced, distributed throughout the study area. Plot size was estimated by the minimum area calculation procedure (Braun-Blanquet, 1979; Rivas-Martínez, 2007, 2011a). The recorded ecological parameters for each phytosociological relevés included: slope (º), plot size (m²), lithological composition, altitude (m a.s.l.), vegetation height (m or cm) and vegetation cover (%). All the relevés have been georeferenced in UTM coordinates using satellite data measured on the ground in the inventoried plot using a handheld GPS receiver. The phytosociological synthetic tables methodology has been applied to differentiate between the new associations proposed and other similar ones published previously. This methodology has not been used for subassociations but a complete description and differential species are given. The new syntaxonomical proposals follow the International Code of Phytosociological Nomenclature (Theurillat et al., 2021).

The syntaxonomical scheme shows the associations identified during this work as well as those of other authors that appear in the bibliography obtained for the studied area (Martínez-Parras et al., 1985; Losa-Quintana et al., 1986; Martínez-Parras et al., 1987; Lorite, 2001; Salazar et al. 2001a; Lorite et al., 2003; Rivas-Martínez et al., 2011). The phytosociological database SIVIM (Iberian and Macaronesian Vegetation Information System) was also consulted for the elaboration of the syntaxonomic scheme.

The proposal of Rivas-Martínez et al. (2011) was followed to identify the vegetation series, the characteristic species of the syntaxa and the most precise geo-ecological nomenclature. We follow Pérez-Latorre et al. (2004, 2008) to describe the zone-potential vegetation, using the data from the phytosociological tables and inventories. Soil types follow the FAO classification (2009) and were obtained from De Pedraza (1996). The development of the altitudinal catenas (geosigmetum) follows Rivas-Martínez (2007).

To identify the habitat types included in the Habitats Directive (Council Directive 92/43/EEC), Annex I was consulted, as well as the Atlas and Manual of Habitats of Spain (Rivas-Martínez et al., 2003) and the Andalusian habitat guide (REDIAM, 2020).

Flora

A total of 629 herbarium sheets were collected. The catalogue of vascular flora resulting from our study (Supplementary material) comprises a total of 440 taxa (species and subspecies), 370 from our floristic recording, 58 from our vegetation records and 12 initially from GBIF, belonging to 248 genera in 78 families. This represents almost 19% of the total number of species catalogued in Sierra Nevada (Lorite, 2016, 2020) and nearly 12% when compared to the flora of Eastern Andalusia (Cueto et al., 2014). In the catalogue, 20 taxa (4.5%) are endemic to Sierra Nevada and represent 23.8% of the known 84 endemic species for the whole of Sierra Nevada (Lorite, 2016, 2020). The distribution of species accor ding to large taxonomic groups is as follows: pteridophytes 2.35%, gymnosperms 0.85% and angiosperms 96.8%. In the study area, the predominant floristic element was the Mediterranean (60 taxa; 13.6%), followed by the Iberian-North African (49; 11.13%), European (40; 9.1%), Nevadensian (36; 8.18%), Eurasian (34; 7.72), Holartic (31; 7.05%), Iberian (30; 6.81%), Paleotemperate (25; 5.68%) and Eurosiberian element (17; 3.86%).

Legally protected and threatened Species

The total number of threatened species according to the Red List of Andalusia (Cabezudo et al., 2005) in the study area is 25, of which 17 species are protected by andalusian legislation (Decree 23/2012 and Law 8/2003). The following threat categories are represented: 1 (EX); 1 (CR); 2(EN) and 21 (VU) (Table 3). In Sierra Nevada, with 2348 catalogued species (Lorite et al. 2016, 2020), 123 (5.24%) species of vascular plants are threatened (Cabezudo et al. 2005) of which 61 (2.6%) are legally protected (Decree 23/2012 and Law 8/2003). In the study area, with a total of 440 species and subspecies that make up the floristic catalogue, 25 are threatened (5.68 %) and 17 are protected (3.86%).

The protected/threatened flora is shown in Table 3.

Alien taxa

Only one taxon in the study area, Datura stramonium L. (Solanaceae) can be considered exotic/invasive, which represents 0.2% of the floristic catalogue. It is considered a methaphyte, epecophyte-hemiagryophyte (Sanz-Elorza et al. 2004). It occurs in ruderal and road vegetation.

Species of chorological and biogeographical interest

Hereafter, we briefly highlight other species of interest due to their rarity and/or scarcity or for their biogeographic value, which are present in the study area and/or have been highlighted in previous works (Pavón-Núñez et al., 2020a, 2020b). This group of species is scarcely present in Sierra Nevada and is always associated with the refuge ecosystems inventoried in this work, such as the edges of streams with rising water, deciduous and prostrate gymnosperm undergrowth, mixed deciduous forests, sheltered rocky areas, ditches and wet sheepfolds, thorny-deciduous edges of wet soils and Sphagnum peat bogs. Furthermore, according to their distribution, most of them correspond to disjunctions with their centre of origin in territories located in the Euro-Siberian region and are very uncommon in the south of the Iberian Peninsula (Guerra et al., 2004; Blanca et al., 2011; Pavón-Núñez et al., 2020a).

Information provided for each taxon is as follows: family, ecology, thermotype, phytosociological affinity (Rivas-Martínez et al., 2002; Blanca et al., 2011) and herbarium sheet collected. They also reveal those taxa that are first herbarium citations for Sierra Nevada, Andalusia, and southern Iberian Peninsula.

Epilobium lanceolatum Sebast. & Mauri. (Onagraceae). Moist grasslands and stony mountain slopes. Supra-oromediterranean (Androsacetalia alpinae). MGC 91717.

New for Sierra Nevada and Granada with GBIF her-barium sheet (Pavón-Núñez et al., 2020a).

Fraxinus excelsior L. (Oleaceae). Riparian forests and deciduous rainforests. Meso-supramediterranean (Fagetalia). MGC90704. Second record for Sierra Nevada with herbarium specimen (GBIF, MA 751674) (Pavón-Núñez et al., 2020a).

Geranium divaricatum Ehrh. (Geraniaceae). Ruderal and mountain roadside vegetation. Supra-oromediterranean (Berberidion vulgaris). MGC 90732. Second record for Sierra Nevada as the first record with herbarium specimen (GBIF, MA 01-00614256) comes from Aedo et al. (1998).

Geranium sylvaticum L. (Geraniaceae). Deciduous thorny scrub, cushion and creeping vegetation of high mountains. Supra-oromediterranean (Trifolion medii/Triseto-Polygonion bistortae). MGC 93795. New for Sierra Nevada with herbarium sheet (GBIF)(Pavón-Núñez et al., 2020a).

Moehringia trinervia (L.) Clairv. (Caryophyllaceae). Herbaceous vegetation in mesophilic and humid forest clearings. Thermo-supramediterranean (Fagetalia sylvaticae). MGC 91702. Second record for the south of the Iberian Peninsula with herbarium specimen (GBIF, MGC 72188-1) (Pavón-Núñez et al., 2020a).

Ophioglossum vulgatum L. (Ophioglossaceae). Hygrophilous mountain grasslands. Meso-supramediterranean (Molinion caeruleae). MGC 89223. Second record for Sierra Nevada as herbarium specimen (GBIF, ABH 13660) (Pavón-Núñez et al., 2020a).

Pyrus cordata Desv. (Rosaceae). Cultivated and naturalised within its natural range in mountain areas. Mesosupramediterranean (Frangulo alni-Pyrion cordatae). MGC 95312. New for Andalusia, it had been excluded from the Andalusian catalogue (Cueto et al., 2025).

Quercus x trabutii Hy (Fagaceae). Deciduous forests on acid soils. Meso-supramediterranean (Ilici-Fagion). MGC 90706. New to the south of the Iberian Peninsula (Pavón-Núñez et al., 2020b)

Ranunculus omiophyllus Ten. (Ranunculaceae). Helophytic vegetation along water courses. Supra-oromediterranean (Ranunculion omiophyllo-hederacei). MGC 92482. New to the southern Iberian Peninsula with a herbarium specimen (GBIF).

Ribes uva-crispa L. subsp. austroeuropaeum (Bornm.) Bech. (Grossulariaceae). Deciduous thorny scrub, climatophilous deciduous forests. Supra-oromediterranean (Berberidion vulgaris). MGC 90327.

Rosa dumalis Bechst. (Rosaceae). Deciduous thorny scrub, undergrowth, hedgerows and forest edges. Supra-oromediterranean (Berberidion vulgaris). MGC 89226 A very rare Euro-Siberian taxon in the south of the Iberian Peninsula (Blanca et al., 2011).

Rosa villosa L. (Rosaceae). Deciduous thorny scrub, undergrowth, hedgerows and forest edges. Supra-oromediterranean (Berberidion vulgaris). MGC 91728. New for Sierra Nevada with herbarium sheet (GBIF).

Rubus canescens DC. (Rosaceae). Deciduous thorny scrub, climatophilous deciduous forests. Supra-oro-mediterranean (Prunetalia spinosae). MGC 93860. New for Sierra Nevada and the province of Granada as a herbarium specimen (GBIF).

Sorbus aucuparia L. (Rosaceae). Edges of deciduous forests on siliceous substrate. Supra-oromediterranean (Betulo pendulae-Populetalia tremulae). MGC 92305. It has been cited previously but without a herbarium sheet. First citation for Sierra Nevada with an herbarium specimen (GBIF) (Pavón-Núñez et al., 2020a).

Sphagnum subnitens Russow &Warnst. (Bryaceae). Peat-bogs. Supra-oromediterranean (Erico tetralicis-Sphagnetalia papillosi). MGC5192. Very uncommon in the south of the Iberian Peninsula (Guerra et al., 2004).

Sphagnum auriculatum Schimp. (Bryaceae). Peatsbogs. Supra-oromediterranean (Oxycocco-Sphagnetea). MGC 2097. Very uncommon in the south of the Iberian Peninsula (Guerra et al., 2004).

Vegetation

Of a total of almost 200 plant communities present in the Sierra Nevada natural area (Molero & Marfil, 2017; Muñoz & Molero, 2019) 35 syntaxa are present in the study area. They consitute 17.5% of phytocoenological richness. In the study area, 18 Habitats of Community Interest (HCIs) are present out of 37 catalogued for the whole Sie rra Nevada (Salazar & Valle, 2019), representing 48.6% of the areas HCI richness. These records highlight the value of this territory of just over 20 km² in the Sierra Nevada National Park. Of these 35 syntaxa, 25 are associations, seven sub-associations, two communities and one var iant. We describe five new syntaxa: two new associations, two new subassociations and one new community. In this work, nine syntaxa have been identified for the first time for the studied territory, of which seven are associations, one is a sub-association and another is a variant. Prior to this publication, 21 syntaxa had already been identified in the area by other authors (Quézel, 1953; Arnáiz, 1979; Martínez-Parras & Mole-ro, 1982; Martínez-Parras et al., 1987; Rivas-Martínez, 1987, 2002; Lorite, 2001; Salazar et al., 2001; Lorite et al., 2003). In relation to the first objective of the work, we have described a new type of deciduous forest with Eurosiberian floristic-chorological relationships, placed in the Querco-Fagetea class. It is floristically and ecologically differentiated from the marcescent forests of Quercus pyrenaica, which was, until now, the only climatophilic deciduous forests considered to exist in the entire Sierra Nevada in its Nevadense sector (Martínez-Parras & Molero, 1982; Martínez-Parras et al., 1985; Molero & Marfil, 2017). The other new association constitutes a complete disjunction for the southern Iberian Peninsula of the hydrophytic communities with Ranunculus omiophyllus (Braun-Blanquet & Tüxen, 1952; Rivas-Martínez et al., 2002). Regarding the two new sub-associations, they constitute southward radiations of deciduous shrub and thorny vegetation characterised by species of a more northern optimum (Blanca et al., 2011; Castroviejo, 2021) and also constitutes the border and upper catenal contact of the new deciduous forest association. Regarding the new communities, the ash groves with Fraxinus excelsior and its hybrid with Fraxinus angustifolia subsp. angustifolia could be the southernmost localities on the European continent together with those located in Sierra Tejeda (Cabezudo et al., 2011). The ash hybrids were taxonomically differen tiated from the parent species by the dark brown colour of the dormant buds, the large size of the leaflets, and the fact that they had more teeth than secondary veins. The second community is a majadal with Poa bulbosa, a type of grazed grassland, whose existence was unknown in the siliceous Sierra Nevada (Pérez-Raya, 1987).

New records on plant associations and communities

Five plant associations and communities have been identified for the first time in the study area:

Montio fontanae-Ranunculetum omiophylli Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana ass. nova (Table 4).

Holotypus ass.: Table 4, relevé 8. Granada, Dehesa del Camarate, Cuenca Alta del río Alhama de Lugros. Date: 27.07.2023. UTM: 30S477823/4112404.

Characteristic species: Ranunculus omiophyllus and Montia fontana subsp. fontana.

Diagnosis: association dominated by Ranunculus omiophyllus, which grows in small shallow pools connected to permanent streams with cold, oligotrophic water and with spring and summer phenology. It is a southern vicariant (reaching Sierra Nevada) of the Myosotido stoloniferae-Ranunculetum omiophylli Rivas-Martínez, Fernández-González, Pizarro, Sánchez-Mata & Sardinero in Rivas-Martínez et al. 2002, association described by Rivas-Martínez et al. (2002) for the Carpetano-Ibérico-Leonesa and Luso-Extremadurensean subprovinces in the centre of the Iberian Peninsula.

It has its optimum in the supra- and oromediterranean thermotypes of the Nevadensian sector although relict because of its scarcity. Another association with similar ecology (little ponds and streams) was included in Ranunculetum hederacei (R. Tüxen & Diemont 1936) Libbert 1940 by Lorite et al. (2003), but it differs from the new association by the presence of Ranunculus hederaceus and the absence of R. omiophyllus. Association of great environmental importance, as it develops in streams and irrigation channels, very characteristic and threatened ecosystems in Sierra Nevada (Salazar & Valle, 2019).

The different floristic composition (Table 5) of both associations is statistically reflected at the alliance level; in Montio fontanae-Ranunculetum omiophylli ass. nova, the characteristic species belong to the Cardamino-Montion typical of cold water streams poor in bases in Eurosiberian environments (Rivas-Martinez et al., 2011). On the contrary, in Myosotido stoloniferae-Ranunculetum omiophylli Rivas-Martínez, Fernández-González, Pizarro, Sánchez-Mata & Sardinero 2002, it belongs to Myosotidion stoloniferae of cold oligotrophic waters in Oroiberian Carpetan-Leonese and Western Orocantabric territories (Rivas-Martinez et al., 2011).

Community of Poa bulbosa (Table 6)

Diagnosis: grassland of hemicryptophytes, therophytes and geophytes dominated by Poa bulbosa growing on deep siliceous soils derived from micaschists and quartzites, subjected to grazing. They are preferably located in the supramediterranean thermotype with at least a sub-humid ombrotype. Synsuccessionally, they evolve from a nutrient-rich and green grass pasture from the beginning of autumn and winter to a dry pasture of therophytes and preferably nitrophilous Compositae especies from late spring to early summer (Rivas-Martínez et al., 2011). This type of grazed grassland on siliceous soils was unknown in Sierra Nevada, although a basophilous community was described by Pérez-Raya (1987).

Lonicero arboreae-Crataegetum granatensis Bolós 1954 corr. Rivas-Martínez, T. E. Díaz, Fernández-González, Izco, Loidi, Lousa & Penas 2002 nom. invers. propos in Cabezudo et al., (2016).

ribetosum austroeuropaei Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana subass. nova (Table 7).

Holotypus subass.: Table 7, relevé 3. Granada, Dehesa del Camarate, El Tentadero. Date: 16.06.2022. UTM: 30S476359/4114282.

Characteristic and differential species: Ribes uva-crispa subsp. austro-europaeum, Rosa villosa, Rosa dumalis, Rosa sicula and Geranium divaricatum.

Diagnosis: microphanaerophytic (2–5 m), chionophilous deciduous thorny shrubland, typical of the upper supramediterranean and lower oromediterranean thermotypes of the Nevadensian sector, developing on deep temporo-hygrophilous soils derived from micaschists and quartzites. The association is characterized by Lonicera arborea and Crataegus granatense, which generate the greatest biomass. The sub-association ribetosum austroeuropaei is endemic and micro-topographic, occurring in localised areas on the northern slopes of Sierra Nevada and is characterised by the frequent presence of characteristic and differentiating taxa of Berberidion vulgaris Br.-Bl. 1950 such as Ribes uva-crispa subsp. austro-europaeum, Rosa villosa, Rosa dumalis, Rosa sicula or Geranium divaricatum. It would be a phytocenological singularity due to its rarity and its relict situation that would connect these southern deciduous thorny shrublands of Lonicero arboreae-Berberidion hispanicae O. Bolòs 1954 with those existing in the Eurosiberian mountains of the central and northern Iberian Peninsula (Berberidion vulgaris) (Rivas-Martínez et al., 2011). As the characteristic species are also located in other northern, upper parts of several basins of Sierra Nevada (rivers Genil, Monachil, Maitena, see GBIF), the presence of this new subassociation is possible there. It constitutes the seral preforest mantle of the higher altitude forest of the association Poo nemoralis-Prunetum avium ass. nova.

Genisto versicoloris-Juniperetum nanae Quézel 1953 corr. Rivas-Martínez, Fernández-González & Loidi 1999 rosetosum villosae Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana subass. nova (Table 8).

Holotypus subass.: Table 8, relevé 2. Granada, Dehesa del Camarate, Cuenca Alta del río Alhama, scrubland bordering hygromorphic grassland. Date: 2.07.2023. UTM: 30S477695/4112133

Characteristic and differential species: Rosa villosa, Rosa dumalis, Geranium sylvaticum, Aquilegia vulgaris subsp. nevadensis and Primula elatior subsp. lofthousei.

Diagnosis: the typical subassociation (juniperetosum hemisphaericae) is an oromediterranean sub-humid siliceous xerophytic shrubland, dominated by Juniperus sabina and Juniperus hemisphaerica in the Nevadensian sector, well adapted to the summer dryness, intense winter cold, snow and strong winds, at the altitude where it grows (Losa-Quintana et al., 1986). The rosetosum villosae subass. nova would represent a mesophilic subassociation of the high mountain juniper shrubland, frequently in ecotone with hygromorphic grasslands “borreguiles”, on humid siliceous substrates of oro-mediterranean microclimatic zones. It may also be considered as the preforest mantle of a hypothetic relict but exinct forest of Betula pendula subsp. fontqueri (Salici capreae-Betuletum fontqueri Molero & Rivas-Martínez in Rivas-Martínez et al., 2002), nowadays represented by isolated individuals in this ecosystem (Ruiz-Girela et al., 2001). The presence of rare, relict or endemic taxa of eurosiberian optimum within the creeping juniper shrub, such as Geranium sylvaticum, Primula elatior subsp. lofthousei or Pedicularis comosa subsp. comosa together with thorny shrub species such as Rosa villosa and Rosa dumalis (Berberidion vulgaris Br.-Bl. 1950) clearly differentiates this ecosystem from the typical, which thrives in more extreme environmental conditions and includes xerophytic species such as Festuca indigesta and Thymus serpylloides. As some of the characteristic species are also located in other northern basins of Sierra Nevada (Genil, Monachil, see GBIF), the presence of this new subassociation is possible there.

Poo nemoralis-Prunetum avium Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana ass. nova (Table 9). (Berberido hispanicae-Aceretum granatensis sensu Molero & Marfil 2017 nomen nudum, art. 2)

Holotypus ass.: Table 9, relevé 4. Granada, Dehesa del Camarate, Horcajo de Camarate. Date: 17.07.2019. UTM: 30S477724/4115971.

Characteristic species: Prunus avium, Fraxinus excelsior, Moehringia trinervia, Epilobium montanum and Poa nemoralis.

Diagnosis: deciduous, mixed climatophilic and temporihygrophilic forests growing in shady ravines and canyon bottoms with deep eutrophic soils close to neutral pH derived from micaschists and quartzites, with an optimum in the supramediterranean subhumid thermotype of the Nevadense sector. The tree layer is dominated by Prunus avium and/or sometimes by Sorbus aria and Acer opalus subsp. granatense, with noteworthy presence of Taxus baccata, Fraxinus excelsior and Quercus x trabutti (Ilici-Fagion Br.-Bl. 1967). It is a sub-Mediterranean relict association, with a notable presence of taxa characteristic for Quercetalia pubescentis Klika 1933, where it was initially included. In protected and well-preserved areas, in addition to the dominant species (Prunus avium), several relict and rare species characteristic for Fagetalia sylvaticae, such as Fraxinus excelsior, Moehringia trinervia or Epilobium montanum are present, together with some differential nemoral plants, such as Poa nemoralis or Polygonatum odoratum. The rare presence of some Prunetalia spinosae species is remarkable, e.g. Rhamnus cathartica or Rosa dumalis. Homalothecium meridionale is a noteworthy bryophyte epiphyte on the base of trunks. This forest could be interpreted as an impoverished, relict, southern irradiation of the Betulo-Populetalia tremulae, which would occasionally reach, from the Eurosiberian Region, the microclimatic zones of the northern slope of Sierra Nevada. An ecological similar situation shows the Geo urbani-Coryletum avellanae ulmetosum glabrae Pavón-Núñez & Pérez-Latorre 2010 subassociation, endemic to the Alcaracensian subsector, Subbaetic sector, Baetic province. The adjacent catenal marcescent forests of Quercus pyrenaica (Adenocarpo-Quercetum pyrenaicae aceretosum granatensis) develop in a lower altitudinal position or in zonal climatic soils compared to Poo nemoralis-Prunetum avium ass. nova. The name Berberido hispanicae-Aceretum granatensis was proposed by Molero & Marfil (2017), without a table of inventories, for Acer opalus subsp. granatensis woodlands occupying similar habitats in Sierra Nevada.

The synthetic table (Table 10) shows comparison between the new association (Poo nemoralis-Prunetum avium) and the two similar plant communities previously described in the literature (Adenocarpo decorticanti-Quercetum pyrenaicae and Aceri granatensis-Fraxinetum angustifoliae). In the new association elements characterisic for the Fagetalia order dominate, which is unique, as mentioned in the previous paragraph, and clearly separates it from the Adenocarpo decorticanti-Quercetum pyrenaicae association, where the majority of species are characeristic for Quercetalia pubescentis or Quercetalia roboris. With regard to Aceri granatensis-Fraxinetum angustifoliae, the differences are notable, characterised by a dominant number of Populetalia albae species. In summary, the table reflects three distinct phytosociological orders, which differentiate each of the three associations.

Community of Fraxinus excelsior (Table 11)

Diagnosis: woody mesophilic and edaphohygrophilous winter deciduous community, dominated mainly by ash trees (Fraxinus excelsior, Fraxinus angustifolia and their hybrid F. excelsior x angustifolia), occasionally accompanied by wild cherry trees (Prunus avium) or willows (Salix atrocinerea). Rubus ulmifolius is abundant in the thorny fringe, Rubus canescens and Rhamnus cathartica may be present, as well as Berberis hispanica. The herbaceous layer contains very rare and scarce nemoral species in Sierra Nevada. Characteristic species of Fagetalia such as Moehringia trinervia are concentrated in small, well-preserved areas and, where ferns such as Athyrium filix-foemina are also frequent. This habitat is always found in the vicinity of permanent watercourses in very localised areas of protected and shady valley bottoms, on fluvisols, soils close to neutral pH in the supramediterranean subhumid thermotype of the Nevadense sector. This community could be derived by altitude and more mesic conditions from the Aceri granatensis-Fraxinetum angustifoliae Molero & Pérez-Raya in J. M. Losa, Molero, Casares & Pérez-Raya 1986.

Syntaxonomical scheme

The syntaxonomical scheme presents the complete catalogue of vegetation types of the studied area and the novelties that are underlined (associations, subassociations, communities, and, where suitable, variants). A short description of the syntaxa with physiognomic and ecological data, and synchorology is provided. Associations that were identified for the first time in this work in the studied area are marked with in bold and underlined. The code for habitats of community interest listed in the Annex I of Directive 92/43/EEC is indicated in bold in brackets following the syntaxon name.

• I. Amphibious vegetation of freshwaters, springs and fens

• Ia. Vegetation of lakes, springs, fens and bogs

  MONTIO-CARDAMINETEA Br.-Bl. & Tüxen ex Br.-Bl. 1948

  • Montio-Cardaminetalia Pawłowski in Pawłowski, Soko-łowski & Wallisch 1928

    • Ranunculion omiophyllo-hederacei Rivas-Martínez, Fernández-González, Pizarro, Sánchez-Mata & Sardinero 2002

      • 1. Montio fontanae-Ranunculetum omiophylli Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana ass. nova (3110_0) [Hidrophytic vegetation of cold oligotrofic water]

    • Myosotidion stoloniferae Rivas-Martínez, T.E. Díaz, F. Prieto, Loidi & Penas 1984

      • 2. Community of Cratoneuron commutatum and Anagallis tenella [Oligotrophic cormophytic bryophytic community of waterlogged or water-splashed rock-covered areas.]

• PHRAGMITO-MAGNOCARICETEA Klika in Klika & Novák 1941

  • Nasturtio-Glycerietalia Pignatti 1954

    • Glycerio-Sparganion Br.-Bl. & Sissingh in Boer 1942

      Glycerienion fluitantis (Géhu & Géhu-Franck 1987) Molina 1996

      • 3. Glycerio declinatae-Eleocharidetum palustris Rivas-Martínez & Costa in Rivas-Martínez, Costa, Castroviejo & Valdés 1980 [Vegetation consisting of small helophytes in oligotrophic waters.]

      Nasturtion officinalis Géhu & Géhu-Franck 1987

      • 4. Glycerio declinatae-Apietum nodiflori Molina 1996 [Association of crassiphilous helophytes of oligotrophic fresh waters with little source]

  • Magnocaricetalia Pignatti 1954

    • Caricion broterianae (Rivas-Martínez, Fernández-González & Sánchez-Mata 1986) Molina 1996

      • 5. Caricetum camposii-cuprinae Salazar, Lo-rite, Cano & F. Valle in Salazar, Lorite, A. García, J. Torres, Cano & F. Valle 2001 [Association dominated by caespitose hemicryptophytes of considerable size occupying the centre of streams and rivers]

• SCHEUCHZERIO PALUSTRIS-CARICETEA NIGRAE Tüxen 1937

  • Caricetalia nigrae Koch 1926

    • Caricion nigrae Koch 1926

      • 6. Ranunculo alismoidis-Caricetum intricatae Martínez-Parras, Peinado & Alcaraz 1987 [Hygro-turbated grassland with permanent hydro-morphic soils and standing waters]

      • – caricetosum intricatae

• II. Chasmophyte, epiphyte and scree vegetation

• IIa. Chasmophyte vegetation of rock crevices

  ASPLENIETEA TRICHOMANIS (Br.-Bl. in Meier & Br.-Bl. 1934) Oberdorfer 1977

  • Androsacetalia vandellii Br.-Bl. in Meier & Br.-Bl. 1934

    • Saxifragion nevadensis Rivas-Goday & Rivas-Martínez 1971

      • 7. Sarcocapnetum speciosae J. Lorite 2001 [Out-cropping siliceous rock crevice communities]

• III. Synanthropic, fringe and megaphorbic vegetation

• IIIa. Synanthropic vegetation

  ARTEMISIETEA VULGARIS Lohmeyer, Preising & Tüxen ex von Rochow 1951

• – Onopordenea acanthii Rivas-Martínez, Báscones, T.E. Díaz, Fernández-González & Loidi 2002

  • Carthametalia lanati Brullo in Brullo & Marcenò 1985

    • Urtico piluliferae-Silybion mariani Sissingh ex Br.-Bl. & O. Bolòs 1958

      • 8. Community of Silybum marianum and Carduus tenuiflorus sensu Aguiar 2000 [Thistle and tall grasses communities]

• IIIb. Fringe and megaphorbic vegetation

  GALIO-URTICETEA Passarge ex Kopecký 1969

  • Galio aparines-Alliarietalia petiolatae Görs & Müller 1969

    • Galio-Alliarion petiolatae Oberdorfer & Lohmeyer in Oberdorfer, Görs, Korneck, Lohmeyer, Müller, Philippi & Seibert 1967

      • 9. Myrrhoidi nodosae-Alliarietum petiolatae Rivas-Martínez & Mayor ex Fuente 1986 (6430) [Megaphorbs in shady, humid and nitrogenous forest edge environments]

        • – nepetosum granatensis Salazar, Lorite, A. García, Torres, Cano & F. Valle 2001

    • Balloto-Conion maculati Brullo in Brullo & Marcenó 1985

      • 10. Heracleo granatensis-Urticetum dioi cae Ríos & Alcaraz in Ríos 1996 [Scionitrophilous megaphorbic riparian community with deep soils]

  • Calystegietalia sepium Tüxen ex Mucina 1993

    • Filipendulion ulmariae Segal 1966

      • 11. Aquilegio nevadensis-Ranunculetum granatensis Martínez-Parras, Peinado & Alcaraz 1987 (6430) [Megaphorbs in shady, humid and nitrogenous forest edge environments]

      • 12. Ranunculo granatensis-Cochlearietum megalospermae Salazar, Lorite, Cano & F. Valle 2001 [Megaphorbic dense grassland, growing on siliceous rocks and oligotrophic waters with strong currents]

• MULGEDIO-ACONITETEA Hadač & Klika in Klika 1948

  • Adenostyletalia Br.-Bl. 1930

    • Cirsion flavispinae Quézel 1953

      • 13. Aconito nevadensis-Senecietum elodis Quézel 1953 [Summer phenological megaphorbic communities in cool, organic-rich soils surrounding streams]

• TRIFOLIO-GERANIETEA Müller 1962

  • Origanetalia vulgaris Müller 1962

    • Origanion virentis Rivas-Martínez & O. Bolòs in Rivas-Martínez, T. E. Díaz, F. Prieto, Loidi & Penas 1984

      • 14. Elymo hispanici-Brachypodietum sylvatici Gómez-Mercado & F. Valle 1991 [Hemicryptophytic scyophyllous grassland of deciduous forests]

• VI. Supratimberline climactical zonal vegetation on cryophilous geliturbated soils

• VIa. West-mediterranean orophilous siliceous vegetation

  FESTUCETEA INDIGESTAE Rivas Goday & Rivas-Martínez 1971

  • Festucetalia indigestae Rivas Goday & Rivas-Martínez in Rivas-Martínez 1964

    • Nevadension purpureae Quézel 1953

      • 15. Erigeronto frigidi-Festucetum clementei Quézel 1953 (6160) [Mediterranean orophyllous grasslands]

      • 16. Sideritido glacialis-Arenarietum pungentis Quézel 1953 (6160) [Mediterranean orophyllous cushion scrublands]

• VII. Grassland and meadow vegetation

• VIIb. Perennial xerophytic grassland

  FESTUCO-BROMETEA Br.-Bl. & Tüxen ex Br.-Bl. 1949

  • Agrostietalia castellanae Rivas Goday in Rivas-Martínez, Costa, Castroviejo & E. Valdés 1980

    • Agrostion castellanae Rivas-Goday 1958 corr. Rivas-Goday & Rivas-Martínez 1963

      • 17. Euphrasio willkommii-Festucetum amplae Martínez-Parras, Peinado & Alcaraz 1987 (6510_1) [Siliceous perennial grasslands]

• POETEA BULBOSAE Rivas-Goday & Rivas-Martínez in Rivas-Martínez 1978

  • Poetalia bulbosae Rivas-Goday & Rivas-Martínez in Rivas-Goday & Ladero 1970

    • Periballio-Trifolion subterranei Rivas-Goday 1964

      • 18. Community of Poa bulbosa (6220_2) [Mediterranean siliceous grazed grasslands of perennial and annual species]

• VIIc. Meadow and chionophilous grassland vegetation

  MOLINIO-ARRHENATHERETEA Tüxen 1937

  • Holoschoenetalia vulgaris Br.-Bl. ex Tchou 1948

    • Molinio-Holoschoenion vulgaris Br.-Bl. ex Tchou 1948

      • 19. Cirsio micranthi-Scirpetum holoschoeni Lorite, Salazar, Cano & F. Valle in Salazar & al. 2001 [Brushy pastures]

• NARDETEA STRICTAE Rivas Goday in Rivas Goday & Rivas-Martínez 1963

  • Campanulo herminii-Nardenalia Rivas-Martínez, Fernández-González & Sánchez-Mata 1986

    • Plantaginion nivalis Quézel 1953

      • 20. Nardo strictae-Festucetum ibericae Quézel 1953 (6230_1) [High mountain siliceous meadows with moist soils all year round]

      • 21. Ranunculo acetosellifolii-Vaccinietum uliginosi Quézel 1953 (6230_1) [Microland on stony soils with permanent summer humidity]

      • 22. Armerio splendentis-Agrostietum neva-den sis Quézel 1953 (6230_1)

      • – agrostietosum nevadensis

      • – plantaginetosum nivalis Martínez-Parras, Peinado & Alcaraz 1987 [High mountain siliceous grasslands with temporarily wet soils in summer]

• VIII. Heathland, dwarf scrub and scrub vegetation

• VIIIa. Heathland and dwarf scrub vegetation

  CISTO-LAVANDULETEA Br.-Bl. in Br.-Bl., Molinier & Wagner 1940

  • Lavanduletalia stoechadis Br.-Bl. in Br.-Bl., Molinier & Wagner 1940

    • Cistion laurifolii Rivas-Goday in Rivas-Goday, Borja, Monasterio, Galiano & Rivas-Martínez 1956

      • 23. Halimio viscosi-Cistetum laurifolii Martí nez-Parras & Molero-Mesa 1982 (4030_2) [Semi-continental siliceous Cistus laurifolius shrublands]

• VIIIb. Seral and mantle shrublands

  CYTISETEA SCOPARIO-STRIATI Rivas-Martínez 1975

  • Cytisetalia scopario-striati Rivas-Martínez 1975

    • Adenocarpion decorticantis (Rivas-Martínez & F. Valle ex F. Valle 1985) Rivas-Martínez, Fernández-González & Loidi 1999

      • 24. Cytiso scoparii-Adenocarpetum decorticantis Valle 1981 [Large sized broom on deep siliceous soils]

• RHAMNO-PRUNETEA Rivas-Goday & Borja ex Tüxen 1962

  • Prunetalia spinosae Tüxen 1952

    • Pruno-Rubion ulmifolii O. Bolòs 1954

      • 25. Rubo ulmifolii-Rosetum corymbiferae Rivas-Martínez & Arnáiz in Arnáiz 1979

      • – rosetosum corymbiferae

        var. with Adenocarpus decorticans [Prickly scrubby with brooms]

    • Lonicero arboreae-Berberidion hispanicae O. Bolòs 1954

      • 26. Lonicero arboreae-Rhamnetum catharticae Martínez-Parras & Molero 1983 [Serial high thorny scrub of mixed deciduous forests]

      • 27. Lonicero arboreae-Crataegetum granatensis Bolós 1954 nom. inv. propos in Cabezudo, B., Casimiro Soriguer-Solanas, C., García-Sánchez, J., & Pérez-Latorre, A. V. (2016) (5110_1) [Hawthorn and wet fringes]

      • – loniceretosum arboreae

      • – ribetosum austroeuropaei Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana subass. nova [Deciduous prickly scrubby on wet and shady soils]

• IX. Forest, woodland, potential natural vegetation

• IXa. Marshy, chionophilous, pioneer and climactic riparian shrublands and woodlands

  SALICI PURPUREAE-POPULETEA NIGRAE (Rivas-Martínez & Cantó ex Rivas-Martínez, Báscones, T.E. Díaz, Fernández-González & Loidi 1991) Rivas-Martínez, Fernández-González, Loidi, Lousa & Penas 2001

  • Populetalia albae Br.-Bl. ex Tchou 1948

    • Osmundo-Alnion (Br.-Bl., P. Silva & Rozeira 1956)

      • Dierschke & Rivas-Martínez in Rivas-Martínez 1975

        • 28. Carici camposii-Salicetum atrocinereae Salazar, Lorite, Cano & F. Valle in Salazar, Lo-rite, A. García, J. Torres, Cano & F. Valle 2001 (92A0_2) [Supramediterranean willows riparian forests]

        • – salicetosum atrocinereae

        • – salicetosum capreae Salazar, Lorite, Cano & F. Valle in Salazar, Lorite, A. García, J. Torres, Cano & F. Valle 2001

        • 29. Carici camposii-Alnetum glutinosae (Salazar, Lorite, Cano & Valle in Salazar, Lorite, García-Fuentes, Torres, Cano & Valle 2001) Pérez-Latorre, Pavón-Núñez & Hidalgo-Triana 2011 [Supramediterranean alder riparian forests] (identified by the authors as an observation near the border of the studied area)

  • IXb. Eurosiberian and mediterranean climactic zonal and potential natural vegetation

    JUNIPERO SABINAE-PINETEA SYLVESTRIS Rivas-Martínez 1965 nom. invers. propos. Mucina et al. 2016

    • Juniperetalia hemisphaericae Rivas-Martínez & J.A. Molina in Rivas-Martínez, Fernández-González & Loidi 1999

      • Genisto versicoloris-Juniperion hemisphaericae Rivas-Martínez & J.A. Molina in Rivas-Martínez, Fernández-González & Loidi 1999

        • 30. Genisto versicoloris-Juniperetum nanae Quezel 1953 corr. Rivas-Martínez, Fernández-González & Loidi 1999 (5120) [High mountain juniper prostrate forest]

        • – juniperetosum nanae

        • – rosetosum villosae Pavón-Núñez, Pérez-L atorre & Hidalgo-Triana subass. nova [Mesophilic faciation of the high mountain juniper prostrateforest]

        • 31. Genisto versicoloris-Cytisetum nevadensis Rivas-Martínez & Molero 2011(5120) [High mountain cushion siliceous shrublands]

  • QUERCETEA ILICIS Br.-Bl. ex A. & O. Bolòs 1950

    • Quercetalia ilicis Br.-Bl. ex Molinier 1934

      • Quercion broteroi Br.-Bl., P. Silva & Rozeira 1956 em. Rivas-Martínez 1975 corr. Ladero 1974

        • 32. Adenocarpo decorticantis-Quercetum rotundifoliae Rivas-Martínez 1987 (9340) [Continental holm oak forests]

        • – quercetosum rotundifoliae

  • QUERCO-FAGETEA Br.-Bl. & Vlieger in Vlieger 1937

    • Quercetalia roboris Tüxen 1931

      • Quercion robori-pyrenaicae (Br.-Bl., P. Silva, Rozeira & Fontes 1950) Rivas-Martínez 1975

        Quercenion pyrenaicae Rivas-Martínez 1975

        • 33. Adenocarpo decorticantis-Quercetum pyrenaicae Martínez-Parras & Molero-Mesa 1982 (9230) [Quercus pyrenaica oak forests]

        • – quercetosum pyrenaicae

        • – aceretosum granatensis Martínez-Parras & Molero-Mesa 1982 [Mesophilic mixed oak forest] Quercetalia pubescentis Klika 1933

      • Aceri granatensis-Quercion fagineae (Rivas-Goday, Rigual & Rivas-Martínez in Rivas-Goday, Borja, Esteve, Galiano, Rigual & Rivas-Martínez 1960) Rivas-Martínez 1987

        • 34. Poo nemoralis-Prunetum avium Pavón-Núñez, Pérez-Latorre & Hidalgo-Triana ass. nova (9180) [Deciduous, mixed climatophilic and temporo-hygrophilic forests]

    • Fagetalia sylvaticae Pawłowski in Pawłowski, Soko-łowski & Wallisch 1928

      1. 35. Community of Fraxinus excelsior (91B0) [Deciduous, riparian ash and hybrids mixed mesophilic forests]

    • Betulo pendulae-Populetalia tremulae Rivas-Martínez, Fernández-González, Loidi, Lousã & Penas 2001

      • Betulion fontqueri-celtibericae Rivas-Martínez & M. Costa in Rivas-Martínez et al. 2002

        • 36. Salici capreae-Betuletum fontqueri Mole-ro & Rivas-Martínez in Rivas-Martínez & al. 2002 (92B0_2) [Andalusian high mountain birch trees forests]

Zone-potential vegetation

The Table 12 summarises the potential of the climatophyllic vegetation zones and relates their ecological characteristics across the different cenotopes of the study area.

Altitudinal catenal distribution of vegetation in the study area

Figure 4 illustrates the altitudinal and slope-orientation-dependent (geosigmetum) distribution of the forests and climax vegetation in the study area.

Figure 4: