Contribution to the knowledge of the edaphoxerophilous communities of the Samana Peninsula (Dominican Republic)

Abstract

The Samana Peninsula belongs to the biogeographical North Sector of the Caribbean-Atlantic Subprovince (Hispaniola Province, Caribbean-Me- soamerican Region). In the past the Peninsula was separated from the rest of Hispaniola but today it is joined by a small strip of land made up of Quaternary sediments in the Gran Estero. Rainfall records are as high as 2,339 mm. The Io value is 7.3 (i.e., humid ombrotype) and Ti/Tic values are 741/675. These conditions give rise to an infratropical thermotype. The Samana Peninsula forms a geomorphological unit dominated by karstic materials, limestones, schists and marls. Despite the heavy rainfall rates, the presence of escarpments (farallones) gives rise to an edaphoxerophilous community. Species such as Pilosocereus polygonus, Zamia debilis, Agave antillarum, Eugenia samanensis, Bursera simaruba, Capparis fexuosa, Ficus velutina, Opuntia dellinii, Comocladia dodonaea, Stigmaphyllum emarginatum are not infrequent in this plant community. This edaphoxe- rophilous community is rich in endemic species and is dominated by Coccotrinax gracilis, Agave antillarum, Leptocereus weingartianus and, to a lesser extent, by Eugenia samanensis. The presence in the peninsula of 134 endemic species justifies considering this a biogeographical territory (A4) within the North Sector (Cano et al., 2010)