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Windward Islands dry forests

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The Windward Islands dry forests ecoregion is sparsely distributed among the Windward Island Group of the Caribbean’s Lesser Antilles. It is typically found as an intermediate gradient between the more mesichabitat characterized by moderate soil moisture, high-elevation forests and the xeric, coastal areas. Much of this ecoregion has been substantially altered by shifting cultivation. Many areas that were once dry evergreen or semi-evergreen seasonal forest, are now cultivated and dominated by farms, rural villages, roads, pastures and banana tree patches. This ecoregion shares flora and fauna with adjacent moist forests and, in some areas, with species native to coastal habitats. Arid coastal areas and inaccessible interior mountains put a disproportionate amount of human-related pressures (i.e., agricultural expansion, roads, buildings) on this ecoregion. Consequently, conservation attention is of particular importance in these dry forests.

caption St. Lucia. (Photograph by WWF/Allan Smith)

Location and general depiction

This ecoregion is found in limited area on several of the Caribbean Basin Windward Islands. Specifically, this includes small portions of Martinique, St. Lucia, St. Vincent, Grenada and Carriacou of the Grenadines. The ecoregion is characterized by steep topography and is most often found in the intermediate area between the rugged interior-island mountains and the flatter, xeric coastal areas.

The Windward Islands extend south from 15° 45' to 11° 45' N and from 60° 45' to 62° 00' W. These islands are found in the trade wind belt and lie upwind, in terms of the prevailing south-easterly wind, of the Leeward Islands. The mountainous terrain of these islands creates great micro-climatic variability within short distances therefore capture a great deal of the moisture within the air masses entering the region from the Atlantic. Hurricanes and tropical storms pass over the islands during rainy season of summer and fall. The interior highlands of these larger islands also receive rainfall in the drier winter months and additional amounts in the summer months. Annual rainfall in the interior highlands ranges from 10,000 millimeters (mm) in Dominica to 3750 mm for the lower-elevation mountains in Grenada. In contrast, coastal areas receive lesser amounts ranging from 1000 mm on Dominica to 1600 mm at the southern end of St. Vincent. The dry forest ecoregion falls between these two extremes due to its moderate relief and elevation.

caption WWF

The Windward Islands form a volcanic island arc consisting of lava flows, ash, and pyroclastic deposits ranging from Miocene to recent in age. Some limestones are interspersed between the volcanic layers. Typically, lava flows outcrop on the steeper slopes and ash underlies the gentler slopes. St. Lucia, and Martinique are predominantly composed of acid andesite and dacitic rocks. Pyroclastic flow deposits, volcanoclastics, and lava domes are typical for these islands. Characteristic soils in the ecoregion are clay-based, and, due to the proximity to coastal areas and higher population densities, often susceptible to significant erosion.

The dry forest ecoregion surrounds the central, mostly primary rain forest. It consists of an irregular band of secondary forest and dry woodland. Much of this ecoregion has been dramatically altered by shifting cultivation, leaving behind abandoned gardens that often generate groves of fern trees. Many areas that were once dry evergreen or semi-evergreen seasonal forest, are now cultivated and dominated by farms, rural villages, roads, pastures and banana stands. On Saint Lucia, where much of this ecoregion is found, a large proportion of the vegetation has been altered by agricultural practices and urban developments. Characteristic forest plant species are generally an association of Didymopanax and Charianthus. In general the dry forests contain a high proportion of aggressive, light-loving species, younger trees and trees that more easily withstand disturbances of the soil, plus a profusion of ferns and mosses.

Biodiversity Features

Table 1. Endemic bird species in the Windward Islands dry forest ecoregion.
Common Name Species Location
St. Vincent Parrot Amazona guildingii St. Vincent
St. Lucia Parrot Amazona versicolor St. Lucia
Imperial Parrot Amazona imperialis Dominica
Red-necked Parrot Amazona arausiaca Dominica
Whitsling Warbler Catharopeza bishopi St. Vincent
House Wren Troglodytes aedon St. Vincent + St. Lucia
St. Vincent Solitaire Myadestes genibaris St. Vincent
St. Lucia Black Finch Melanospiza richardsoni St. Lucia
Semper’s Warbler Leucopeza semperi St. Lucia
St. Lucia Oriole Icterus laudabilis St. Lucia
Martinique Oriole Icterus bonana Martinque
Blue-headed hummingbird Cyanophaia bicolor Dominica + Martinique
White-breasted Thrasher Ramphocinclus brachyurus Martinique + St. Lucia

By virtue of its proximity to the Windward Islands Moist Forest Ecoregion, which is very high in terms of biological richness and diversity, this ecoregion also has abundant flora and fauna. Due to its restricted size, distribution and similarity to the moist forest ecoregion however, little information exists regarding plants and animals specific only to this area.

Endemic species common to the moist ecoregion likely also use this drier ecoregion periodically and thus should be considered in descriptive literature and future conservation efforts. Notable endemics are the St. Vincent parrot (Amazona guildingii, VU), the St. Lucia parrot (Amazona versicolor), and the Grenada Dove (Leptotila wellsi), all critically endangered. Other endemic avian species in this ecoregion are more common (Table 1). Eleven island-endemic reptile species occur: Anolis oculatus, A. roquet, A. luciae, A. trinitatis, A. griseus, Eleutherodactylus shrevei, E. martinicensis, E. euphronides, Typhlops tasymicris, Bothrops carribaeus and Sphaerodactylus microlepis.

Current Status

Conservation issues relevant to the greater Windward Islands are applicable to the specific dry forests of this ecoregion. Martinique, since 1953, is subject to the same legislation as metropolitan France, producing a lot of conservation involvement at the local level by French non-governmental organizations (NGOs). Yearly revisions to French legislation are produced by the Direction de la Protection de la Nature on Martinique. St. Lucia’s forestry conservation issues are directed by the Government’s Forestry Division. Forestry resources are divided into strictly protected, protected but permitting limited production on an individual tree basis, and production forests. The Wildlife Protection Act identifies wildlife that is absolutely protected, partially protected, and unprotected. Six species of mammals and reptiles and 79 species of birds are given extensive protection, while 37 bird taxa are partially protected under legislation. The Fer de Lance viper, the mongoose, and several pest mice and rat species may be hunted or trapped year round. A national park system on St. Vincent has been considered, but is not fully approved or implemented. St. Vincent’s forests are being threatened by encroaching agriculture even though all forests above 305 metres (m) are theoretically protected by legislation. Grenada has one established protected area (Grand Etang Forest Reserve), however, there is no substantive national park legislation that provides adequate authority either to establish or to manage national parks and protected areas.

Types and Severity of Threats

The more arid forests, by virtue of being of lower relief and closer to population-related development, are more susceptible to agricultural encroachment, hunting, and also suffer from limited enforcement of wildlife and environmental legislation. An improved infrastructure of roads on most of the Windward Islands has allowed greater access to previously undisturbed forests and accelerated conversion of primary forest to agricultural plantations. Regionally, two aspects of current forestry legislation are considered weak, penalties for forest offenses are too low for deterrence, and there is no mechanism for ongoing coordination of decision-making between forestry and other sectors concerning land-use planning and development control.

As with most other areas in the Lesser Antilles, all extant mammal species in this ecoregion were introduced by Amerindian or Colonial settlers and subsequently threaten native species. Common are the mongoose (Herpestes officinarum), agouti (Dasyprocta antillensis), opposum (Didelphis marsupialis), pig (Sus scrofa), and domestic cat and dog. Four regionally endemic bats can be found in separate portions of this ecoregion: Monophyllus plethodon, Ardops nichollsi, Brachyphylla cavernarum, and Myotis martiniquensis. There are no remaining endemic rodents in the Lesser Antilles.

Justification of Ecoregion Delineation

The dry forests ecoregion of the Windward Islands were designated according to Caribbean Conservation Association survey reports for each island. In order to maintain our broad-scale coverage we lumped the dry woodland terrestrial life zones from all of the Leeward Islands which contained this habitat type. Littoral vegetation and agricultural areas were also included, when bordering dry woodland formations. On Martinique we followed Portecop, and for boundaries with mangroves we followed Lacereda.

References and Further Reading

  • Caribbean Conservation Association. 1991. St. Lucia: Environmental Profile. St. Michael, Barbados.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: St. Vincent, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: Grenada, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: St. Vincent, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: St. Lucia, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: Grenadines, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Caribbean Conservation Association. 1980. Survey of conservation priorities in the Lesser Antilles: Barbados, Preliminary Data Atlas. Eastern Caribbean Natural Area Management Program, Caribbean Conservation Association, the University of Michigan and the United Nations.
  • Faaborg, J. R., and W. J. Arendt. 1985. Wildlife assessments in the Caribbean. Rio Pedras, Puerto Rico: Institute of Tropical Forestry.
  • Fairbridge, R.W. 1975. Windward Islands. Page 667 in R.W. Fairbridge, editor, The Encyclopedia of World Regional Geology, Part 1: Western Hemisphere. Stroudburg, Dowden, Hutchinson and Ross. ISBN: 047025145X
  • Johnson, T. H. 1988. Biodiversity and conservation in the Caribbean: profiles of selected islands. Cambridge, UK.: International Council for Bird Preservation. ISBN: 0946888140
  • Lacereda, L.D. 1994. Conservation and sustainable utilization of mangrove forests in Latin America and Africa regions. Part 1, Latin America. Mangrove Ecosystems Technical Reports. Vol. 2. International Society for Mangrove Ecosystems. International Tropical Timber Organization.
  • National Parks and Wildlife Unit (NPWU). 1988. Plan and policy for a system of national parks and protected areas in Grenada and Carriacou. St Georges: Forestry Department, Ministry of Agriculture.
  • Organization of Eastern Caribbean States (OECS). 1986. Dominica, description of national legislation related to natural resources management (first stage analysis). Natural Resources Management Project. Organisation of Eastern Caribbean States, Castries, St. Lucia.
  • Rand McNally. 1988. World atlas of nations. New York: Rand McNally. ISBN: 0528833154
  • Portecop, J. 1975. Carte ecologique de la Martinique. Map 1:75,000. Centre Universitaire Antilles, Guyane, Martinique.
  • United Nations Environment Programme (UNEP), Caribbean Environment Programme. 1996. Status of Protected Area Systems in the Wider Caribbean Region. CEP Technical Report. No. 36.
  • Walsh, R. P. D. 1985. The influence of climate, lithology, and time drainage density and relief development in the volcanic terrain of the Windward Islands. Pages 93-122 in I. Douglas, and T. Spencer, editors, Environmental Change and Tropical Geomorphology. London: Allen and Unwin. ISBN: 0045510741
  • Woods, C. A. 1985. Endemic rodents of the West Indies: the end of a splendid isolation. Proceedings from a workshop of the IUCN/SSC Rodent Specialist Group, #4. p. 11-19.

 

Disclaimer: This article contains certain information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

 

 

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Citation

Fund, W. (2014). Windward Islands dry forests. Retrieved from http://www.eoearth.org/view/article/51cbef487896bb431f69d5ba

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