Location and General Description
The cactus scrublands of Cuba were dispersed in strips or small patches on the shore, particularly in the southeastern part of the island. From west to east we find them on the Guanahacabibes peninsula (at Punta del Holandés and from Cabo Corrientes to Cabo Francés), in the southeast of Isla de la Juventud (in Punta del Este), on the northern coast from Bahía de Cabañas to Punta Hicacos (from Havana to Varadero), on the southern coast from Cienfuegos Bay to San Pedro Bay (from Juragoa to Casilda), and in Oriente, where this type of vegetation reaches its highest expression. In Oriente, these scrublands are found in the south at Cabo Cruz, in a small strip along the southern coast of the province of Santiago de Cuba and Guantánamo, widening in the easternmost area from the city of Santiago de Cuba to Punta de Maisí and Punta del Fraile. There are also small patches on the northern coast of Oriente, as in Punta Mula and around Punta Piedra del Mangle (Cuba 1997, WWF-US 2000). This ecoregion has a desert-like appearance that is defined by a semi-desert climate, with average annual precipitation of 800 mm or less, a dry period of 9-11 months and average temperatures of 26ºC (Borhidi and Muñiz, 1980). In Oriente, the high mountains block the access of the moist winds from the northwest, causing the dry local climate. In addition, this narrow strip of vegetation is directly affected by maritime winds acting as an additional drying factor. The principal type of soil on which these scrublands are found are coastal rendzinas, derived from coralline limestone rock, that are very skeletal and have a karstic structure. Cuba also has xeric scrublands with a high level of endemism, but these are not coastal and are associated primarily with serpentine soils; these are the cuabales and charrascales (Bisse 1988).
There are different plant formations associated with this ecoregion, with a predominance of columnar cacti, as well as other succulent plants (that store water) adapted to the extremely dry environments (Áreas de Interés 1997). The most characteristic and abundant correspond to the xeromorphous coastal and subcoastal scrubland with abundant succulents, also called coastal manigua, which is represented above all on the southern coast of Oriente (Bisse 1988, Biodiversidad de la biota cubana 1997). It is a thorny scrubland up to 6 m high with palms and numerous succulent plants, primarily in the cactus group. Examples of the species of shrubs and small trees that usually maintain their foliage throughout the year in this formation are: Bourreria virgata (cafecillo), Capparis cynophallophora (mostacilla), Eugenia buxifolia (guairaje), Bursera glauca, B. cubana, Croton spp., Cordia spp., Calliandra colletioides, Caesalpinia spp., Acacia spp., Phyllostylon brasiliense, Albizzia cubana and Guaiacum officinale. Of the cactus, we can mention Opuntia dillenii(tuna) and O. militaris, Harrisia eriofora (pitahaya), H. taetra (jijira), Pilosocereus robinii (miramar), Dendrocereus nudiflorus (aguacate cimarrón), Agave spp. (maguey), Melocactus spp. (erizos) and Leptocereus spp.
Xerophytic plants of the families cactaceae, agavaceae, euforbiaceae and moraceae predominate (Oldfield 1997). Another type of scrubland, the coastal thorny semidesert, has an abundance of thorny plants up to 6 m high and some (but not many) succulent plants that give it a desert-like appearance. The same cacti as in the previous formation can be found as well as the following plants: Cordia sebestena (vomitel), Hippomane mancinella (manzanillo) and Plumeria filifolia (lirio de costa).
In addition, there is coastal schlerophyllous scrubland up to 3 m high with emergent trees up to 5-6 m high; it is characterized by having plants with hard (schlerophyllous) leaves and corresponds to a formation in transition to the dry forest. Species that can be found include Picrodendron macrocarpum (yana), Maytenus buxifolia (carne de doncella), Belairia spinosa (yamaguey), Brya ebenus (granadillo) and Diospyrus grisebachii (ébano). Finally, we have the rocky coastal scrublands, open vegetation generally with little species diversity and small stunted shrubs, succulents and herbaceous plants over the karstic "dog’s tooth" soil on high coasts where they are subject to the spray of the sea and strong winds. The following species are found: Borrichia arborescens (romero de playa), Messerschmidtia gnaphalodes (incienso de playa) and Sesuvium maritimun (verdolaga de playa) (Habitats terrestres Cuba 1997, Bisse 1988).
Due to the fragmentary distribution pattern of these scrublands all along the patches on the island’s coast, together with the quite specific climatic and edaphic characteristics in whichy they develop, the flora is particularly rich in endemisms of xerophytic plants, i.e., plants adapted to dry climates and nutrient-poor soils, possibly including 20% of the total number of species and representing an important center of speciation. The scrublands on the southern coast of the central region (from Juragoa to Casilda) (CPD Cb1) and particularly those on the southern coast of Oriente (from Punta Maisí to Cabo Cruz and adjoining coastal areas) (CPD Cb2) are considered to be part of two of the three most important centers of plant diversity and endemism on the island (Davis et al. 1997).
Some endemisms of this ecoregion that bear mentioning are Pilosocereus brooksianus, Leptocereus maxonii, L. sylvestris, L. santamarinae, L. arboreus, Opuntia macracantha, Opuntia dillenii, Melocactus matanzanus M. holguinensis, M. acunae, Escobaria cubensis, Agave albescens, A. acicularis and A. grisea, some of them seriously at risk of extinction (Oldfield 1997). In the Oriente region, two endemic genera should be noted: Heppiella and Caribea, as well as the presence of relict species (Olson et al. 1996). Some of the adaptations characteristic of this xerophytic vegetation are succulence, schlerophília, microphília and plants with CAM metabolism (Bisse 1988).
This ecoregion also has high diversity and endemisms among fauna. For example, in the section between Maisí and Guantánamo there are 29 species of reptiles, 4 of them strictly endemic to the area and 15 endemic to the island. Among insects, this area contains some unique elements unique in Cuba, whose closest relatives are found in the southwestern deserts of North America (P. Alayo Dalmau, personal communication). Various species of Sphaerodactylus (Gekkonidae) and Anolis spp. unique to the ecoregion are endangered to varying degrees, as are land pulmonates (snails) like those of the genera Polymita and Coryda, various species of scorpions and other arachnids, which also have great varieties of form in these biotopes, along with significant endemism (Biodiversidad de la biota cubana 1997, Áreas de Interés 1997).
According to Dinerstein et al. 1997, less than half of the original vegetation of this ecoregion has been lost and there is at least one block of this vegetation larger than 200 Km2 (nearly 10% of the ecoregion). The degree of fragmentation is relatively low, there is a low habitat conversion rate (<0.5% per year in the period 1990-1995) and the degree of protection for the ecoregion is low, in that the ecoregion has at least one protected area with an intact habitat block larger than 100 Km2 (less than 5% of the total for the ecoregion). Accordingly, the ecoregion is considered to have a vulnerable conservation status and its biological distinctiveness is important at the local level. Its conservation priority is important in national terms. According to Olson et al. 1996, the gaps in taxonomic botanical data are sufficient to hamper conservation projects, and thus additional botanical data is needed for such projects to be effective.
The biogeographic data on the ecoregion is greater than the taxonomic data but not adequate. According to Oldfield 1997, the locations of these scrublands with conservation priority and a high degree of endemism are the coast and the lowlands from Guantánamo Bay to Punta Maisí (particularly notable for the conservation of succulent plants), the coast and lowlands of Bacanao, between Pilón and Cabo Cruz, between Gibara and Puerto Padre Bay, from Playa Girón to Punta Mulas, the northern coast of the Hicacos peninsula to Bahía Honda and the southern coast of the Guanahacabibes peninsula. According to Habitats terrestres Cuba 1997, the coverage with this type of vegetation on the island is now about 1%.
Important protected areas for the conservation of this ecoregion because they contain it in part are in Oriente, the Desembarco del Granma National Park (258 Km2, IUCN category II and World Heritage Site since 1999) and the Bacanao Biosphere Reserve (846 Km2, IUCN category IX) within the Gran Parque Sierra Maestra Integrated Management Area (5,270 K m2, IUCN category VIII); on the south central part of the island, the Escambray Integrated Management Area (1,870 Km2, IUCN category VIII); and in Occidente, the Mil Cumbres Integrated Management Area (166 Km2, IUCN category VIII), the Guanahacabibes Peninsula Biosphere Reserve (1,015 Km2, IUCN category IX), the Cabo Corrientes Natural Reserve (16 Km2, IUCN category I), the Punta Francés-Punta Pedrales National Park (174 Km2, IUCN category II) and the Punta del Este Natural Touristic Area on Isla de la Juventud (53 Km2, IUCN category V) (CEP 1996, UNEP-WCMC 1997).
Types and Severity of Threats
According to Dinerstein et al. 1995, the principal threats to this ecoregion are grazing, felling of trees, habitat conversion and the exploitation of resources associated with increased urbanization. In some areas of western Cuba, communities of Dendrocereus nudiflorus and Pilosocereus robinii have been replaced by sisal crops (Agave sisalana and A. furcroydes) (Oldfield 1997).
Justification of Ecoregion Delineation
The delineation’s for the Cuban Cactus Scrub were derived by from the Coastal Spiny Semidesert regions of Hernandez (1989). Comparisons were also made with other studies (Borhidi 1991).
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Prepared by: Ugo D'Ambrosio
Reviewed by: In process