Location and General Description
The Maracaibo dry forests are located in the northeastern coastal area of Venezuela. The majority of the ecoregion is located in the state of Zulia in the Maracaibo Basin; the remainder lies in the state of Trujillo. The ecoregion borders the Sierra de Perijá to the west, and the Cordillera de Mérida and the Sierra of Baragua to the south and northeast respectively. There are also patches of mangrove habitat interspersed along the shores of Maracaibo Lake, in the interior of the ecoregion. A major network of roads extends through the basin; one of these roads is the Pan American Highway. This area contains the Bolivar oil field, the largest field in Venezuela, located on the northeastern shores of Lake Maracaibo. In fact, most of the oil in Venezuela comes from around the oil fields in Lake Maracaibo (Harcourt and J. Sayer 1996).
The entire ecoregion extends through coluvio-alluvial plains that range in elevation from 0 to 500 m. Annual temperature ranges from 16 to 26 oC. This area receives less than 1000mm of rain annually and is strongly seasonal. The terrain is flat and the surrounding hills and mountains become transitional moist forests at higher elevations. The area is traversed by rivers that flow into the Maracaibo Basin from the surrounding mountains. The Palmar, Negro, Lora and Catatumbo Rivers start in the Sierra de Perija. The Escalante River starts in the south Andes. The Motatan, Misoa, and Pachango Rivers start east of the Maracaibo Basin (Venezuela 2000).
After fifty years of human intervention, little is left of the natural dry forests. The remaining native vegetation consists of small isolated patches that include savannas with trees and deciduous forests. Some of the species found in the fragmented savannas are Axonopus canascens, Bowdichia virgilioides, Borreria sp., Byrsonima crassifolia, Bulbostylis capillaris, Curatella americana, Copernicia tectorum, Galactia jussieuana, and Xylopia aromatica. Very small fragmented areas of deciduous dry forests are found west of Lake Maracaibo. Some of the flora in these areas include Acacia glamerosa, Bulnesia arborea, Bourreria cumanensis, Copaifera venezuelana, Gyrocarpus americanus, Jacquinia pungens, Malpighia glabra, Myrospermum frutescens, Piptadenia flava, and Ritterocereus griseus (Huber and Clara Alarcon 1988). In abandoned areas, secondary vegetation includes Cecropia sp., Jacaranda copaia, Xylopia aromatica, etc.
Endemic terrestrial mammals characteristic of this ecoregion, and of others in dry forests in Colombia and Venezuela, are the opossum (Marmosa xerophila), and the vesper mouse (Calomys hummelincki). Marmosa is well adapted to dry habitats, and is also found in deciduous forest, while the vesper mouse is mainly found in sandy grasslands (Eisenberg 1989).
The number of endemic birds in this and other ecoregions is restricted to the small dry areas of northern Venezuela, including the Maracaibo Basin. The following endemic birds are under the status "least concern": the pygmy swift (Tachornis furcata), buffy hummingbird (Leucippus fallax), chesnut piculet (Picumnus cinnamomeus), white-whiskered spinetail (Synallaxis candei), black-backed antshrike (Sakesphorus melanonotus), slender-billd tyrannulet (Inezia tenuirostris), tocuyo sparrow (Arremonops tocuyensis), and vermilion cardinal (Cardinalis phoeniceus) (Stattersfield et al. 1998).
There are few and very small natural habitats remaining due to the high population and intensive land use in the ecoregion. Grazing has especially affected the southeastern and southwestern areas of Lake Maracaibo (Huber and D. Frame 1988). The main impact on the natural vegetation has been caused by shifting cultivation, and by an extensive network of roads surrounding Lake Maracaibo (Huber n. d.). There are not any protected areas within this dry forest ecoregion.
Types and Severity of Threats
Continuous conversion of remaining natural habitat in the southern part of the Basin is of great concern especially without any protected areas to keep any remnants of this ecoregion safe from conversion. Also of concern to all living things of this ecoregion is the recent findings that some of the rivers that traverse the Basin and flow into the Maracaibo Lake, within this ecoregion, are polluted with pesticides and fertilizers (Venezuela 2000). The greatest threat to this ecoregion unfortunately includes the total destruction of this habitat type including all unique vegetation and fauna associated with it.
Justification of Ecoregion Delineation
These are one of several dry forest regions of in the vicinity of the Maracaibo Basin and Cordillera de Mérida. This ecoregion encompasses Lake Maracaibo, and preliminary delineation’s follow Huber and Alarcon (1988). Linework was subsequently reviewed and modified by Robert Smith (pers. comm), who identified the region as unique based on species endemism and historic coverage’s.
Eisenberg, J. F. 1989. Mammals of the Neotropics: The Northern Neotropics Volume 1. The University of Chicago Press, Chicago.
______. 1996. Venezuela.C. Harcourt and J. Sayer, editors. The Conservation Atlas of Tropical Forests: The Americas. Simon & Schuster, New York.
Huber, O. and D. Frame. 1988. Venezuela.D. Campbell and H. D. Hammond , editors. Floristic Inventory of Tropical Countries. The New York Botanical Garden, Bronk.
Huber, O. n. d. Coastal Cordillera Venezuela. Retrieved (2001) from: <http://www.nmnh.si.edu/botany/projects/cpd/sa/sa1.htm>.
Huber, O. and Clara Alarcon. 1988. Mapa de Vegetacion de Venezuela. Republica de Venezuela, Ministerio del Ambiente y de los Recursos Naturales Renovables, Caracas, Venezuela.
Smith, R. Personal communications. June 16, 1994. Concerning delineation’s of northern
Stattersfield A.J., M. J. Crosby, A. J. Long, and D. C. Wege, editors. 1998. Endemic Bird Areas of the World: Priorities for Biodiversity Conservation. BirdLife International, Cambridge, UK.
Venezuela, G. o. 2000. Primer Informe de Venezuela sobre Diversidad Biologica. Ministerio del Ambiente y de los Recursos Naturales, Oficina Nacional de Diversidad Biológica., Caracas, Venezuela.
Prepared by: Claudia Locklin
Reviewed by: In process