From the bioclimatic standpoint, the thermotype in the Antilles ranges from the infratropical to the supratropical (the latter only in Hispaniola) [ 1]. The temperature in the supratropical thermotype drops to 0° C in winter. The dominant thermotypes are the infra- thermo- and mesotropical, and the ombrotype ranges between the semiarid and the hyperhumid. This study of Cuban pine forests is conducted in the infra-, thermo- and mesotropical thermoptypes and in rainy environments with rainfalls of between 1300-2000 mm. The ombrotype ranges from the lower subhumid to the upper humid, in agreement with Rivas-Martínez et al. [ 2] and Cano et al. [ 3] on the island of Hispaniola, in sites with a dominance of broadleaved forest; however, in areas with steep slopes or special substrates where there is a water deficit, the pine forest should be considered edaphoxerophilous [ 4,5,6].

Regarding biogeography, we have followed the work of Rivas-Martínez et al. [ 7], which establishes three biogeographical provinces: Florida, Cuba and the Antilles, all part of the Caribbean-Mesoamerican Region. When studying the distribution of Melastomataceae in Central America and the distribution of 2050 endemic species on the island of Hispaniola, Cano et al. [ 8,9,10] established the superprovince of the Western Antilles in which they include Cuba, Jamaica and the Florida peninsula. They maintain the biogeographical province of Florida with the sectors defined by Rivas-Martínez et al. [ 7] and the province of Cuba with two subprovinces: the Cuban subprovince, with three biogeographic sectors (Eastern, Central and Western), and the Jamaican subprovince, with the Jamaican sector. The superprovince of the Central-Eastern Antilles is established for the rest of the islands (Hispaniola, Puerto Rico and the Lesser Antilles) and the Eastern Antilles biogeographic province is created for Puerto Rico and the Lesser Antilles. The island of Hispaniola is considered a biogeographical province with two biogeographical subprovinces: the Central subprovince (Central sector) with acid substrates and over 500 endemic species, and the Caribbean-Atlantic subprovince with basic substrates and six biogeographic sectors with 19 district areas, which are subsequently studied by Cano Ortiz et al. [ 11]. For the biogeographic study we have taken into consideration several factors, the geology of the territory, endemic species, distribution and origin of the flora, as well as the existing plant communities and their catenal contacts. [ 8,9,10]

Solid knowledge about flora and vegetation provides a valuable basis for the implementation of biodiversity management and conservation measures [ 12,13,14]. The gaps of knowledge, both in native and alien species, are still today the subject of interest by numerous scholars around the world [ 15,16,17,18]. If flora checklists provide new, complete and updated information about the presence of plant taxa in a given geographic area at small or large scale, syntaxonomical studies allow to review, improve and update knowledge on species composition of different plant communities that occupy several habitats in the world.

Pine forests are habitats widespread in the world, very important for providing ecosystem services and for their ecological role [ 19]. If some of them are well known and studied under different points of view, others less. It is the case of the Caribbean pine forests of Cuba and Hispaniola

For the study of the pine forests in the Caribbean, the phytosociological method was used, since the existing studies in Hispaniola and Cuba are of this type. Thus we highlight the different plant associations, which constitute habitats of special protection due to the high rate of endemism.

On the northern or windward face of the mountains, there is a predominance of broadleaved or rainforest of Magnolia, Prestoea, Ocotea, Podocarpus, Cyathea (Ocoteo-Cyrilletea racemiflorae Borhidi 1996) [ 20], while the pine forest is on the Caribbean or leeward face at low altitudes above the sea of clouds. The genus Pinus comes from North America and reached the Greater Antilles via the Florida migratory route. Cuba is the location of Pinus caribaea Morelet, P. tropicalis Morelet [Syn: Pinus cubensis Griseb. & Carab. var. terthrocarpa Griseb.] and, according to some authors, P. cubensis Griseb. & Carab. (endemic) [Syn: Pinus maestrensis Bisse; P. occidentalis Sw. var. cubensis (Griseb.) Silva]. However, following the criterion of Borhidi [ 21,22] and López Almirall [ 23], we maintain the taxon P. maestrensis Bisse. Some authors also cite P. occidentalis var. cubensis in Cuba. In Hispaniola there is a dominance of P. occidentalis (endemic) and in a disperse manner P. caribaea. Only P. caribaea is located in Puerto Rico, where it forms different types of forest. Other plant communities developing exclusively in Hispaniola are the hemicryptophyte grass scrublands in the supratropical bioclimatic belt, dominated by Danthonia domingensis Hack. & Pilg., a plant that is endemic to the Cordillera Central and that coexists with the endemic plant Deschampsia domingensis Hitchcock & Ekman, occupying the open areas left by the pine forest of P. occidentalis, described by Cano et al. [ 24] as Dendropemom phycnophylli-Pinetum occidentalis Cano, Velóz, & Cano-Ortiz 2011. Several researchers have studied the flora and vegetation of the two largest islands in the Caribbean, Cuba and Hispaniola, in recent decades [ 25,26,27,28,29,30,31,32,33,34,35].

The statistical study of the several pine forest vegetation units with the rank of association, subassociation and variant reveals anomalies as to the veracity of the syntaxa according to the International Code of Phytosociological Nomenclature (ICPN) [ 36]. Borhidi [ 21,22] proposed including the pine forests growing on sandy soils derived from andesites in rainy sites in the order Pinetalia occidentalis-maestrensis Borhidi 1991, and assigns this order to the class Ocoteo-Cyrilletea racemiflorae Borhidi 1996; whereas Cano et al. [ 37] includes the mixed pine forests on rainy sites in the order Pinetalia tropicalis-caribaeae Samek & Borhidi in Borhidi 1996. It is currently necessary to maintain the order Pinetalia occidentalis-maestrensis that contains the alliances Pinion maestrensis Borhidi 1996 and Cyrillo nepensis-Pinion cubensis Borhidi & Muñiz in Borhidi 1996. Both orders are included in the class Byrsonimo crassifoliae-Pinetea caribaeae Samek & Borhidi in Borhidi 1996, which represents the pure and mixed pine forests in the lower-lying regions and hills of Central America, Cuba, Hispaniola, Puerto Rico, Bahamas and Florida. These forests grow on acid to neutral soils, sometimes slightly basic, derived from white sands, slate, sandstone and occasionally limestone.

The aim of this study is to review the different syntaxa of pine forests on the islands of Cuba and Hispaniola, since most of these forests growth on special substrates, in which there is a high number of endemic plants. Thanks to this, it will be possible to act all the necessary actions to protect plants and habitats in these two islands.

The high mountains in Cuba that developed over millions of years were the Sierra Maestra, Sierra Escambray (Guamuhaya), Sierra Turquino at 1974 m a.s.l., and Pico Cuba at 1972 m a.s.l. The highest altitudes in Hispaniola are the Cordillera Central with Pico Duarte (3175 m a.s.l.), Pico del Yaque (3125 m a.s.l.), la Rosilla (2860 m a.s.l.), Cordillera Septentrional with Pico Diego de Ocampo (1229 m a.s.l.), and other mountain ranges such as Bahoruco, Hotte and La Selle, Cordillera Oriental. Finally, in Puerto Rico, the Cordillera Central with altitudes below 1500 m a.s.l. [ 21]. The Cordillera Central (Hispaniola) has a siliceous character and dates from the Cretaceous era period, and is the highest point in the whole Caribbean. The climate in all the Antilles is tropical with frequent and abundant rains on the oceanic face, sometimes exceeding 3,000 mm, and low rainfall on the Caribbean face, at up to 200 mm. The mean temperature is 24 °C, and all the islands are subjected to hurricane winds with speeds of over 200 km/h [ 21,22].

We studied the plant associations in the pine forest on the islands of Cuba and Hispaniola (Figure 1), with 180 relevés corresponding to associations, subassociations, variants and subvariants. A statistical treatment was performed on 706 species distributed in the associations present on the two islands. The flora of these syntaxa is a consequence of the 4 migratory routes and of the speciation that has occurred throughout history due to the isolation of the species. The 181 relevés correspond to the associations and subassociations described. All the samples are located on the islands of Cuba and Dominican Republic.

Sampling plots and phytosociological inventories follow the sigmatist method of Zürich-Montpellier school of Braun-Blanquet [ 38] and collected in current works [ 39]. The plot size and the sampling method carried out by the different authors is correct, according to current phytosociology [ 38]. Regarding the syntaxonomic review, we have taken into account the main current phytosociology studies [ 40,41,42] and the ICPN [ 36]. To differentiate some syntaxa from others, a syntheticTable table was made, in which the floristic differences are clearly observed, likewise we established the Jaccard distance between the typus of the syntaxa to see their similarity / dissimilarity. Regarding the choice of characteristic species and companions, the concepts of current phytosociology are taken into consideration: for this we consider the ecological niche of the species, distribution area, bioclimate, status, plant dynamics as well as catenal contacts.

Ordination analyses are applied (cluster, DCA) to establish the syntaxonomical differences between associations, subassociations and ecological variants. The statistical packages PAST (PAleontological STatistics)© and CAP3 (Community Analysis Package III)© were used for this study. Special reference is made to the type relevés. The types for each association were selected out of the total relevés, and a comparativeTable table was compiled to establish the floristic differences between them.

The cluster and DCA analysis helps us to establish the different groups, the use of the types of each association and subassociation allows us to see the proximity between the groups, and if there really are substantial differences to maintain these phytosociological groups, with the established statistical information, together with the phytosociological analysis and the use of the international code of nomenclature, we establish the proposed syntaxes.

The following plant associations have been described by us [ 16] for the island of Hispaniola, and by Borhidi [ 21,22] and Reyes & Acosta [ 27] for Cuba: Clethro-Pinetum maestrensis (CLP), Paepalantho-Pinetum tropicalis (PAP), Byrsonimo pinetorum-Pinetum tropicalis-caribaeae (BYP), Querco-Pinetum caribaeae (QUP), Anemio coriaceae-Pinetum cubensis (ACP), Euphorbio helenae-Pinetum cubensis (EHP), Agavo shaferi-Pinetum cubensis (ASP), Dracaeno-Pinetum cubensis (DCP), Dendropemon phycnophylli-Pinetum occidentalis (DP), Coccotrino scopari-Pinetum occidentalis (CP), Leptogono buchi-Pinetum occidentalis (LP), Panico-Pinetum cubensis subass. typicum var. Evolvulus sericeus (PP), Panico-Pinetum cubensis subass. lyonetosum affinis var. Sida linifolia (PP), Panico-Pinetum cubensis subass. lyonetosum affinis var. Cecropia peltata-Baccharis shaferi var. Vaccinium cubense (PP), Coccocypselo herbacei-Pinetum cubensis subass. typicum var. Bonnetia cubensis var. Dicranopteris flexuosa (CSP), Coccocypselo herbacei-Pinetum cubensis subass. ilicetosum repandae var. de Cinnamomum elongatum var. de Suberanthus stellatus and subass. Schmidtottietosum shaferi (CP), Schmidtottio shaferi-Pinetum cubensis var. Guettarda monocarpa subvar. Euphorbia helenae subvar. Eugenia asperifolia (SP), Schmidtottio shaferi-Pinetum cubensis subass. shaferetosum platyphyllae subass. acrosynanthetosum trachyphylli (SP), Acrosynantho trachyphylli-Pinetum cubensis subass. typicum subass. ossaeetosum shaferi subass. psychotrietosum grandis (AP), Protio fraganti-Pinetum cubensis subass. myrcetosum subass. notodonetosum roigii (PFP), Anthaenantio-Pinetum cubensis var. tipica var. Baccharis scoparioides (ANP), Anthaenantio-Pinetum cubensis subass. euphorbietosum var. tipica var. Aristolochia lindeniana-Rhynchospora crispa (ANP), Anthaenantio-Pinetum cubensis var. Ossaea pauciflora subvar. tipica subvar. Baccharis shaferi-Rajania nipensis var. Evolvulus sericeus-Polygala saginoides subvar. tipica subvar., Arthrostylidium capillifolium (ANP), Anthaenantio-Pinetum cubensis subass. grisebachiabthetosum nipensis var. Gochanatia shaferi subvar. Coccoloba refexa subvar. Clerodendrum nipense (ANP), Arthrostylidio-Pinetum cubensis subass. typicum var. tipica var. Cynanchum brachystephanum, subass. annonetosum sclerophyllae var. tipica var. Eugenia mensurensesis subass. xylosnetosum buxifolii (ARP), Phyllantho mirifico-Pinetum cubensis (PHP), Phyllantho mirifico-Pinetum cubensis subass. pitcairnietosum cubensis (PHP) (Table 1).

The study of Caribbean pine forests reveals two major groups. 1) Pine forest growing on ferritic, ophiolite, serpentine and pyroxenite soils, and included in the phytosociological class Caseario crassinervis-Pinetea cubensis Borhidi & Muñiz in Borhidi 1996; and 2) the second group of pine forests growing on siliceous and limestone substrates, and calcareous sands, which must be included in the class Byrsonimo crassifoliae-Pinetea caribaeae. The cluster analysis perfectly separates the Cuban pine forests from the pine forests on the island of Hispaniola (DP, CP and LP); a certain number of syntaxa described by Reyes & Acosta [ 27] are very close to the group extracted from Borhidi [ 22] (Figure 2).

The dendrogram inFigure figure 2 shows the separation of the different types of pine forests, some being clearly separated, while others are close to each other. Several different groups appear in the cluster to which the inventories studied belong. The inventories of associations collected and described by Borhidi [ 22] belonging to: Paepalantho seslerioidis-Pinetum tropicalis (PAP), Querco-Pinetum caribaeae Borhidi & Capote in Borhidi (1991) (QUP), Anemio coriaceae-Pinetum cubensis (ACP), Euphorbio helenae-Pinetum cubensis (EHP), Agavo shaferi-Pinetum cubensis (ASP) and Dracaeno-Pinetum cubensis (DCP) comprise a single group, and Clethro-Pinetum maestrensis (CLP) and Byrsonimo pinetorum-Pinetum tropicalis-caribaeae (BYP) are separated and constitute separate groups. Concerning the associations, subassociations and variants described by Reyes & Acosta [ 27], some syntaxa are are perfectly separated, whereas in others the separation is not clear. The association Anthaenantio-Pinetum cubensis (ANP) forms a homogeneous group in the cluster, and is very close to Arthrostylidio-Pinetum cubensis (ARP). The group formed by this last syntaxon includes the typus for the association and for the subassociations annonetosum sclerophyllae and xylosmetosum buxifolii. Both associations are localized in Sierra de Nipe. ANP is in the south of Sierra de Nipe, with precipitations ranging 1300-1500 mm and on ferritic soils with high rainfall. ARP is located in the most highlands of the Sierra de Nipe between 600-995 m a.s.l. on an ultramaphic rocky surface and steep slopes, with precipitations that oscillate over 1500 mm. To a large extent both associations share common floristic elements.

The association Panico-Pinetum cubensis (PP) constitutes a clearly differentiated group containing three subgroups, two of which correspond to the relevés in the association, and the subassociation lynetosum affinis. The third subgroup comprises the relevés (59-67) representing the variant with Vaccinium cubense Griseb.

This association is located in rainy areas of the northern area of the Sierra de Nipe on dark ferritic soils, with rainfall of 1500 mm, in north-northeast orientations with rainfall exceeding 1800 mm. It is enriched in Lyonia affinis Urb., which together other species acts as a differential against the type association: for this reason, the authors have established the lyonetosum affinis subassociation.

The following associations belong to group in the cluster: Coccocypselo herbacei-Pinetum cubensis (CP) and the two subassociations ilecetosum repandae and schmidtottietosum shaferi. In this case, both subassociations form a single group that is separated from the relevés in the association. The pine forest association CP is located in the west of Cubillas del Toa, between 400-740 m a.s.l. and consequently in a thermotropical environment, on ultramafic ferritic substrates and with high rainfall over 1800 mm, the upper subhumid ombrotype being.

The same occurs with Acrosynantho trachyphylli-Pinetum cubensis (AP) and its subassociations annonetosum sclerophyllae and psychotrietosum grandis, in which the three typus belong to the same group. AP is present on ophiolite rocks and red fetitus soils, between 400-600 m a.s.l. and with high precipitations, close to 3000 mm: bioclimatically it is found in the thermotropical and in the humid ombrotype.

This is also the case of the subassociations shaferetosum platyphyllae and acrosynanthetosum trachyphylli in the association Schmidtottio shaferi-Pinetum cubensis (SP), myricetosum and notodonetosum roigii in Protio fraganti-Pinetum cubensis (PFP), and pitcairnietosum cubensis in Phyllantho mirifico-Pinetum cubensis (PHP).

The associations SP, PFP and PHP constitute a group in the cluster. SP corresponds to the pine forests of the ophiolitic massif of Moa Baracao on ultramafic substrates, with red ferritic soils: a pine forests that growth between 600-700 m a.s.l. and in environments with rainfall close to 1800 mm, being the upper subhumid thermotropical bioclimate. The association PFP is located at low altitude, below 300 m a.s.l., in ultramafic substrates, interacting above 300 m a.s.l. with the cloud forest. Rainfall is variable, but ranges between 1500-2000 mm. PFP bioclimatically is framed in the upper subhumid thermotropical. Finally, PHP it is a pine forest that also growth on ultramafic materials, in steep reliefs with slopes between 15-30%, and at altitudes between 600-700 m a.s.l., with rainfalls close to 1800 mm, being the upper subhumid thermotropical bioclimate.

All these associations are located on special substrates, have a common flora, but also present a high richness in endemic species, which act as differentiating species between them [ 15].

In the syntaxonomic review carried out, we have taken into consideration the syntaxa described by various authors, with a range of association, subassociation, variants and subvariants. We started from 18 associations (180 inventories), for the islands of Cuba and Hispaniola. However, Reyes & Acosta [ 27] accept 21 syntaxa with association rank, 11 subassociations and 22 variants and subvariants, although they didn’t provide inventories of all syntaxa. In this review, we accept for Cuba 31 associations described by various authors and that comply with the ICPN [ 36], 8 subassociations and 4 variants. For Hispaniola we only have 3 associations described by us in previous works.

In both cases, pine forests occupy large areas of Cuba and Hispaniola, with human actions that cause a decrease of these ecosystems in areas of the Caribbean and elsewhere on the planet [ 43,44]. If we add to this phenomenon changes in rainfalls and temperatures due to climate change [ 45,46], we obtain plant communities that substitute these forests, some of these being invasive communities. It is the case of Prosopis juliflora (Sw.) DC. that it is invasive in much of the world [ 47]. However, the resilience of Pinus species is high [ 48]. These pine forests located on different types of substrates, represent habitats of interest due to their high rate of endemic species, either because they are located on special substrates or because of the mountain effect, since the mountains present an increase in endemics when climbing in altitude [ 24,49].

We include two orders and six alliances with ten plant associations in the class Byrsonimo crassifoliae-Pinetea caribaeae. The forests of Pinus occidentalis on the island of Hispaniola have a different biogeographical distribution and floristic composition from that of the pine forests of Cuba; for this reason, they form separate groups in the DECORANA statistical analyses (Figure 3). In Hispaniola, Cano et al. [ 24] described three plant associations for three different environments. Coccotrino scopari-Pinetum occidentalis (CP) growth on calcareous substrates in the Sierra de Bahoruco. Dendropemon phycnophylli-Pinetum occidentalis (DP) covers large extensions on siliceous substrates in the Cordillera Central, with both associations growing at altitudes above the sea of clouds. Finally, Leptogono buchi-Pinetum occidentalis (LP), located on serpentines in the northeast of the island of Hispaniola (Dajabón). The alliance Rondeletio christii-Pinion occidentalis was described for these pine forests on serpentines on the island of Hispaniola, and assigned to the order Ariadno shaferi-Phyllanthetalia orbicularis Borhidi & Muñiz in Borhidi 1996 and to the class Phyllantho orbicularis-Neobracetea valenzuelanae Borhidi & Muñiz in Borhidi 1996, representing sclerophyllous heaths in submontane areas in western Cuba. These plant communities on serpentines on the island of Hispaniola were not included by their authors in the class Caseario crassinervis-Pinetea cubensis Borhidi & Muñiz in Borhidi 1996, due to their marked floristic difference from Cuban serpentinicolous vegetation, as can be seen in the syntheticTable table we provide (Appendix A,Table A1). There are significant ecological, biogeographical and floristic differences between the three pine forest associations described for the island of Hispaniola, and which clearly separate the three syntaxa, as can be seen in theTable table prepared with the typus (Appendix A,Table A2).

Reyes & Acosta [ 27] include 21 syntaxa with association rank, for which they propose eight new pine forest associations, one new status, and one new combination, in addition to nine new subassociations and two new combinations. The statistical analysis and the synthetic tables for the 180 relevés corresponding to the associations and subassociations included in the different suballiances and alliances show no substantial differences in some cases. The relevés in the association Anthaenantio-Pinetum cubensis created as a new combination, and for which two new combinations are in turn created with the rank of subassociation euphorbietosum and subassociation grisebachianthetosum nipensis, form a clearly characterized and homogeneous group. In this case the association has been typified: Samek’s relevé 39 [ 53,54] is adopted as the type for euphorbietosum, and for the subassociation grisebachianthetosum nipensis, the type relevé of the cluster (141ANP) is relevé 4Table table 14 of Reyes & Acosta [ 27]. Unfortunately, this last subassociation is incorrectly named, as the taxon Grisebachianthus nipensis also belongs to the type relevé of the association ARP, which leads to misinterpretation according to articles 26, 36 and 39 of the ICPN [ 36], as it is a syntaxon that only presents the endemisms Lobelia oxyphylla and Jacquinia robusta as differential in regard to the rest of the type. We therefore propose: jaquinietosum robustae subass. nova. The association Arthrostylidio-Pinetum cubensis represents a homogeneous group in the cluster inFigure 2 together with the subassociations annonetosum sclerophyllae and xylosnetosum buxifolii, which does not occur in the DECORANA ordination analyses. An analysis of the syntheticTable table shows floristic differences between ANP and ARP; however, the Jaccard distance is similar between both associations. The type of the association ARP and the types of its two subassociations show a close Jaccard distance given the similarity between the three syntaxa, and particularly between the type for the association and the type for the subassociation annonetosum sclerophyllae; however floristic differences can be seen in theTable table of type relevés, which together with the different ecology they present allows us to maintain both subassociations. The association Panico-Pinetum cubensis (PP) has been described for the altiplano in the Sierra de Nipe. The cluster analysis for the relevés forms a very homogeneous group, in which the association is differentiated from the subassociation lyonetossum affinis. However, in the Detrended Correspondence Analysis (DCA) the relevés tend to be intermixed with those of ANP and ARP, which is to be expected as they have a certain floristic similarity with these associations, and the Jaccard distance is similar between them (Table 2).

Coccocypselo herbacei-Pinetum cubensis is an association described by its authors for the territories in Cuchillas de Toa at an altitude of 400-700 m asl – and therefore with a thermotropical character – growing on ultramafic substrates and dark red ferritic soils. For this association, its authors describe two subassociations in addition to the type subassociation: ilicetosum repandae and schmidtottietosum shaferi. The ordination analysis for the general cluster inFigure 2 shows a group with all the relevés corresponding to CSP, with two subgroups, one of which contains the typus relevé of the association (75CSP) corresponding to relevé 8Table 4 Reyes & Acosta [ 27]; the other subgroup contains the typus for the two subassociations. Both type relevés are floristically and ecologically very close, and appear to be more a case of ecotones with neighboring associations, as stated by their authors for the subassociation ilicetosum repandae in regard to the contact with the sub-montane tropical and subtropical moist forest, as it happens in Hispaniola [ 20]. Schmidtottietosum shaferi has been characterized by species with a broad distribution, all of which are native, and which have even been used as characteristic plants for both subassociations with the rank of genus, without specifying the species. Schmidtottia shaferi has been used as a characteristic for the suballiance Cyrillo nipensis-Pinenion cubensis, and also gives the name to the subassociation. Schmidtottia shaferi belongs to various associations (Tables A1 and A2), and has been used to name Schmidtottio shaferi-Pinetum cubensis, an association that is very close to the previous one in terms of its floristic similarity, as can be seen in the various ordinations we performed and in theTable table of typus. For this last association, Schmidtottio shaferi-Pinetum cubensis, the authors propose the subassociations shaferetosum platyphyllae and acrosynanthetosum trachyphylli; both form a compact subgroup separated from the type association. It is evident that the subassociation acrosynanthetosum trachyphylli represents an ecotone contact with Acrosynantho trachyphylli-Pinetum cubensis, an association described in the ophiolitic complex in western Cuba and with high rainfall, for which, in addition to the type subassociation, its authors describe the subassociations ossaeetosum shaferi and psychotrietosum grandis. Both subassociations form a subgroup separated from the typus of the association (seeTable table on the comparative analysis of typus); the subassociation ossaeetosum shaferi is characterised by the endemisms Gesneria wrightii Urb., Ilex hypaneura Loes. and Ossaea shaferi Britton & P.Wils. (syn.= Miconia jashaferi Majure & Judd.) However, the subassociation psychotrietosum grandis presents the following species as differentials of the association of native species with a broad distribution: Palicourea dominguensis, Pimenta odiolens, Psichotria grandis, Purdiaea parvifolia and Vanilla bicolor. This subassociation is really a catenal contact with the broadleaved forests and should therefore have been treated as a variant. In the case of Protio fraganti-Pinetum cubensis described for the extreme northwest of the municipality of Baracoa, this is a pine forest whose authors claim is located at low altitudes in islands of ultramafic substrates, contacting at higher altitudes with the tropical and subtropical moist forest. This is therefore an edaphoxeric and thermotropical pine forest located on sites with steep slopes. The general cluster shows that the association (type relevé 111PFP), corresponding to relevé 4Table 11 Reyes & Acosta [ 27], forms a subgroup with the subassociation myricetosum, whereas the subassociation notodonetosum roigii constitutes an independent subgroup. However, Notodon roigii has been used exclusively as a differential species; this is a native plant with a broad distribution. The subassociation myricetosum presents the following endemisms as differential species for the type of the association: Calycogonium cristalensis Urb., Chiococca cubensis Urb., Purdiaea ekmamii Vict. and P. stenopetala Griseb. Finally, as in previous cases the relevés for the association Phyllantho mirifico-Pinetum cubensis represent a homogeneous group in the general cluster, separating into subgroups the relevés corresponding to the association from those of the subassociation pitcairnietosum cubensis; this separation can be observed in the comparative analysis of the typus for the syntaxa.

Therefore, to avoid confusion we propose a change of status for the following subassociations: we propose a change from the subassociation to variant rank for subass. ilicetosum repandae Reyes & Acosta 2012: syn. var. with Ilex repanda; subass. schmidtottietosum shaferi Reyes & Acosta 2012: syn. var. with Schmidtottia shaferi; subass. acrosynanthetosum trachyphylli Reyes & Acosta 2012: syn. var. with Acrosynanthus trachyphyllus; subass. psychotrietosum grandis Reyes & Acosta 2012: var. with Psychotria grandis; subass. notodonetosum roigii Reyes & Acosta 2012: syn. var. with Notodon roigii (article 27 [ 36]).

All the Caribbean pine forests are included in 4 orders and 12 alliances, with a total of 34 plant associations. The high diversity of syntaxa is due to the special characteristics of the territory, as these are islands with a high rate of endemisms and numerous different substrates. Siliceous, basic, and neutral substrates, and ophite, andesite and serpentine rocks are very frequent, leading to a wide range of different soil types. All this is favoured by the special orography of the islands, as there are steep slopes with gradients between 30 and 60°. The analysis of the studies by several authors and by ourselves reveals a high number of syntaxa with the rank of association and subassociation, and ecological and geographic variants. In this work we update several syntaxa based on the nomenclature of the ICPN [ 36] in order to avoid possible nomenclatural conflicts, and we include all the associations described until now. Finally, we propose the following syntaxonomic checklist for all the Caribbean pine forests.

BYRSONIMO CRASSIFOLIAE-PINETEA CARIBAEAE Samek & Borhidi in Borhidi 1996

Pinetalia tropicalis-caribaeae Samek & Borhidi in Borhidi 1996

Acoelorrapho-Pinion tropicalis Samek in Borhidi 1996

Paepalantho seslerioidis-Pinetum tropicalis Sameck 1969

Roigello-Pinetum tropicalis (Samek 1969) Borhidi 1996

Blechno serrulati-Acoelorraphion wrightii Hadac & Hadacová 1971

Byrsonimo pinetorum-Pinetum tropicalis-caribaeae Borhidi & Capote 1991

Neomazaeo-Pinion caribaeae Borhidi 1991

Neomazeo-Pinetum caribaeae (Samek 1973) Borhidi 1991

Guettardo valenzuelanae-Pinetum caribaeae Borhidi 1996

Agavo cajalbanensi-Pinetum caribaeae Sameck 1973 corr. Borhidi 1991

Ilici tuerckheimi-Pinion occidentalis Cano, Veloz & Cano-Ortiz 2011

Dendropemon phycnophylli-Pinetum occidentalis Cano, Veloz & Cano-Ortiz 2011

Coccotrino scopari-Pinetum occidentalis Cano, Veloz & Cano-Ortiz 2011

Pinetalia occidentalis-maestrensis Borhidi 1991

Pinion maestrensis Borhidi 1996

Clethro cubensis-Pinetum maestrensis Borhidi 1991

Pachyantho poiretii-Pinion caribaeae Borhidi & Capote in Borhidi 1991

Querco-Pinetum caribaeae Borhidi & Capote in Borhidi 1991

CASEARIO CRASSINERVIS-PINETEA CUBENSIS Borhidi & Muñiz in Borhidi 1996

Pinetalia cubensis Borhidi & Muñiz in Borhidi 1996

Andropogono reinoldii-Pinion cubensis Borhidi 1996

Shafero-Pinetum cubensis Borhidi & Muñiz 1996

Rhynchosporo cernuae-Pinetum cubensis Borhidi 1996

Guettardo ferrugineae-Pinion cubensis Borhidi 1996

Caseario crassinervis-Pinenion cubensis Reyes in Reyes & Acosta 2012

Anthaenantio-Pinetum cubensis (Samek 1973) Reyes & Acosta 2012

jaquinietosum oxhyphyllae Reyes & Acosta 2012 ex Cano et al.

hoc locoeuphorbietosum Reyes & Acosta 2012

Eugenio-Pinetum cubensis Del Risco, Samek & Reyes 1996

Anemio coriaceae-Pinetum cubensis (Samek 1973) Borhidi 1991

Garcinio-Pinenion cubensis Reyes in Reyes & Acosta 2012

Arthrostylidio-Pinetum cubensis Reyes in Reyes & Acosta 2012

annonetosum sclerophyllae Reyes & Acosta 2012

xylosnetosum buxifolii Reyes & Acosta 2012

Phyllantho mirifico-Pinetum cubensis Reyes & Acosta 2012

Scaevolo-Pinetum cubensis Del Risco, Samek & Reyes 1996

Euphorbio helenae-Pinetum cubensis Borhidi 1996

Agavo shaferi-Pinetum cubensis Borhidi 1996

Vernonio-Pinetum cubensis Samek, Del Risco & Reyes 1996

Dracaeno cubensis-Pinenion cubensis (Borhidi 1991) Reyes in Reyes & Acosta 2012

Dracaeno-Pinetum cubensis Borhidi 1991

Bactri cubensis-Pinion cubensis Reyes in Reyes & Acosta 2012

Panico-Pinenion cubensis Reyes in Reyes & Acosta 2012

Panico-Pinetum cubensis (Samek 1973) Reyes stat. nov. Reyes & Acosta 2012

lyonetossum affinis Reyes & Acosta 2012

Coccocypselo herbacei-Pinetum cubensis Reyes & Acosta 2012

var. with Ilex repanda

var. with Schmidtottia shaferi

Schmidtottio shaferi-Pinetum cubensis Reyes & Acosta 2012

shaferetosum platyphyllae Reyes & Acosta 2012

var. with Acrosynanthus trachyphyllus

Acrosynantho trachyphylli-Pinetum cubensis Reyes & Acosta 2012

ossaeetosum shaferi Reyes & Acosta 3012

var. with Psychotria grandis

Protio fraganti-Pinetum cubensis Reyes & Acosta 2012

myricetosum Reyes & Acosta 2012

var. with Notodon roigii

Clidemio rubrinervis-Pinetum cubensis Del Risco, Samek & Reyes 1996

Gundlachio-Pinetum cubensis Samek, Del Risco & Reyes 1996

Ilici-Pinetum cubensis Reyes, Samek & Del Risco 1996

Agavo albescentis-Pinion cubensis Reyes in Reyes & Acosta 2012

Alvaradoo-Pinetum cubensis Samek, del Risco & Reyes 1996

Cyrillo nipensis-Pinion cubensis Borhidi & Muñiz in Borhidi 1996 (Syn.: Cyrillo nipensis-Pinenion cubensis Reyes in Reyes & Acosta 2012, art. 2b ICPN)

Cyrillo nipensis-Pinetum cubensis Borhid & Muñiz 1991

PHYLLANTHO ORBICULARIS-NEOBRACETEA VALENZUELANAE Borhidi & Muñiz in Borhidi 1996

Ariadno shaferi-Phyllanthetalia myrtilloiis Borhidi & Muñiz in Borhidi 1996

Rondeletio christii-Pinion occidentalis Cano, Cano-Ortiz, Del Río, Veloz & Esteban 2014

Leptogono buchii-Pinetum occidentalis Cano, Veloz & Cano Ortiz 2011

Author Contributions: Conceptualization, Eusebio Cano; Data curation, Ricardo Quinto Canas, José Carlos Piñar Fuentes, Sara del Río, Catarina Meireles and Eusebio Cano; Formal analysis, Ana Cano-Ortiz, José Carlos Piñar Fuentes and Eusebio Cano; Investigation, Ana Cano-Ortiz and Eusebio Cano; Methodology, Ana Cano-Ortiz, and Eusebio Cano; Project administration, Eusebio Cano; Resources, Ana Cano-Ortiz and Eusebio Cano; Supervision Eusebio Cano; Validation, Ana Cano-Ortiz, Ricardo Quinto Canas, José Carlos Piñar Fuentes, Sara del Río and Eusebio Cano; Visualization, Catarina Meireles and Eusebio Cano; Writing – original draft, Ana Cano-Ortiz and Eusebio Cano; Writing – review & editing, Ana Cano-Ortiz, Ricardo Quinto Canas, José Carlos Piñar Fuentes, Sara del Río and Eusebio Cano.

Funding: This research received no external funding.

Data Availability Statement: Not applicable

Conflicts of Interest: The authors declare no conflict of interest.

Appendix A: supplementary material

Table A1 | Synthetic analysis of the syntaxa studied.

Table A2 | Comparative analysis of the typus of the syntaxa studied.