Description
Location and General Description
This ecoregion covers only a small portion of land area in the northwest of Trinidad and the very northern end of Tobago. Both islands lie in close proximity to the South American mainland; separating from the mainland as recently as 1,500 and 11,000 years respectively. This dry forest ecoregion comprises only about 5% of the land area of the island-nation of Trinidad and Tobago. Trinidad and Tobago are the most southerly of the Caribbean’s Lesser Antilles. The two islands have a combined land area of 5,128 km2. Trinidad is currently separated from the mainland at its closest points, in both the north and the south, by distances of approximately 12 km, while Tobago lies another 30 km to the north-east. Both islands lie on the South American Continental Shelf and are directly influenced by the Orinoco River and the South Equatorial Current.
On Trinidad, the principal forest types are: tropical rain forest, semi-deciduous rain forest, littoral woodland, deciduous seasonal woodland, and swamp/mangrove forests. The tropical rain forest is restricted to sheltered mountain valleys of Tobago’s Main Ridge. Lower montane forest, xerophytic rain forest, evergreen formations and some elfin woodland also occurs (Davis et al. 1986; Thelen and Faizool 1980). In Tobago, apart from its smaller size, the paucity of different habitats restricts the number of species by comparison with Trinidad. Also, Tobago’s separation from the mainland at a much earlier time than Trinidad’s likely resulted in the elimination of certain species from Tobago by competition (ffrench 1991).
Biodiversity Features
Little information exists specific to the flora and fauna of this relatively small ecoregion. The following information pertains to Trinidad and Tobago as a whole unless specifically attributed to this dry forest ecoregion.
Resulting from the proximity to, and recent geological split from, the South American mainland, Trinidad and Tobago have a high species to area ratio. The two islands have approximately 2,200 species of flowering plants, 110 that are believed to be endemic to the island, including numerous palms. There are also reported to be over 400 species of birds, 100 species of mammals, 85 species of reptiles and 30 species of amphibians (Huber and Meganck 1987; Kenny et al. 1997).
In contrast to the moist forest ecoregion on Trinidad and Tobago, this ecoregion is characterized by much more open forest, owing to the lack of a proper canopy. There is a greater proportion of deciduous trees and fewer large trees. Mosses and epiphytes are not common owing to the greatly reduced rainfall. Prominent trees in this area include Lonchocarpus punctatus, Bursera simaruba, Machaerium robinifolium and Pithecellobium unguiscati. Along the coast several species of cactus and the century plant (Agave evadens) are common. In the foothills of the Northern Range, especially the area north and east of Port of Spain, Cordia alliodora becomes common in the semi-deciduous forest. A small portion of this ecoregion also is found on the northern tip of Tobago. Here the canopy is at about 15 m and dominant trees include Bursera simaruba, Lonchocarpus domingensis, Coccothrinax australis. Though many of the dominant species are deciduous, the understory is mostly evergreen with Eugenia spp. and Mayepea caribaea prominent.
Birds constitute the largest group of vertebrates on Trinidad and Tobago. The dominant order, as in many other parts of the world, is the Passeriforms, accounting for almost a third of the families represented. The total number of species recorded for the two islands is 433, of which 411 are recorded for Trinidad and 210 for Tobago (ffrench 1991). Trinidad is on one of the main routes of migrants traveling south down the chain of the Antilles from North America. Certain Antillean species join this stream on the way to "wintering" grounds in South America. Another group of species travels north from South America to escape the austral winter. A few of these spill over from the continent into Trinidad but rarely Tobago.
There are approximately 100 indigenous mammal species with bats accounting for over half of the mammalian fauna. The rest of the mammalian group includes the marsupials, edentates, several rodents, primates, a few carnivores, and deer.
About 40 species of snakes can be found in Trinidad with fewer occurring in Tobago. There are five families and about 25 species of lizards in Trinidad and Tobago. Of the amphibians in Trinidad, there are about 30 species in nine families. Tobago has only about one-third the number of species. All are frogs or toads of the order Anura.
Current Status
The Policy for the Establishment and Management of a National Park System in Trinidad and Tobago (Thelen & Faizool 1980) identified 61 areas as needing protection. These areas covered approximately 69,000 ha, and were classified into six different categories including thirteen scientific reserves, eight national parks, eight natural landmarks, thirteen nature conservation reserves, six scenic landscapes and thirteen recreation parks. The eight proposed national parks, Caroni Swamp, Chaguaramas, Madamas, Maracas, Matura, and Nariva Swamp in Trinidad; and in Tobago, Bucco Reef and Eastern Tobago, cover almost half the proposed protected areas system (IUCN 1992) and much of this small ecoregion's remaining vegetated areas.
In the early 1980s the level of conservation management being conducted in the various protected areas was minimal. In wildlife sanctuaries, including the Caroni Swamp, exploitation of timber was a threatening activity (Chalmers 1981). A decade later patrolling in wildlife sanctuaries was still reported to be inadequate, and only Caroni had active habitat management and a warden system. In December 1991, Aripo and Caroni Swamp, Matura Bay and Fishing Pond were listed as gazetted forest reserves under the Forest Ordinance and Grande Riviere was added in 1997. By 1988 there were 13 wildlife sanctuaries totaling ha.
The daily management of biological resources falls under the auspices of the Ministry of The Environment. The Wildlife and National Parks Sections fall under the Forestry Division. The former regulates hunting, conducts wildlife research and implements the CITES and Ramsar Conventions while the latter oversees all state lands that have been designated as national parks or protected areas.
Types and Severity of Threats
Most of this ecoregion is located in northwest Trinidad surrounding the capital city of Port of Spain. This city is the industrial and commercial center and focal point for tourism in the country. Consequently, the surrounding forests have suffered significant alteration due to population growth and agricultural and industrial development. Pronounced habitat alterations relevant to this ecoregion and the whole of Trinidad and Tobago include activities such as crop production of cocoa, coconuts, rice, sugarcane, citrus, and vegetables, hillside cropping, slash and burn cropping, fire climaxes, and plantation forestry of pine and teak. Mining which results in a loss of topsoil, vegetation and fauna is of particular environmental concern.
Conservation-related threats include inadequate protected-area staffing, a need to enact legislation concerning establishment of parks and a lack of public support for resource protection. Legislation is inadequate to prevent excavation, illegal forestry, squatting and other potentially harmful activities. Squatters have invaded many of the sanctuaries and forest reserves (Bacon & ffrench 1972). The former Kronstadt Island, Morne L'Enfer and Valencia wildlife sanctuaries have been mined, quarried or logged to such an extent that in 1988 they were recommended to be degazetted. Forest fires have taken their toll on Trinidad’s forests, especially on the slopes and ridges of the Northern Range. Most are the products of ‘slash and burn’ agriculture, which has consequently led to large areas of secondary growth forest.
Justification of Ecoregion Delineation
The classification of this relatively small patch of dry forest in NW Trinidad and NE Tobago were determined according to Beard (1946 & 1944). Linework however followed the Republic of Trinidad and Tobago map (1990), which classifies this region as a dry forest.
References
Bacon, P.R., and R.P. ffrench. 1972. The wildlife sanctuaries of Trinidad and Tobago. Wildlife Conservation Committee, Ministry of Agriculture, Lands and Fisheries.
Beard, J.S. 1944. The natural vegetation of the island of Tobago, British West Indies. Ecological Monographs 14:135-163.
Beard, J.S. 1946. The natural vegetation of Trinidad. Oxford Forestry Mem. 20. Clarendon Press, Oxford, UK.
CARICOM/FAO/ODA. 1993. National Forestry Action Programme. Trinidad and Tobago. Port of Spain.
Chalmers, W.S. 1981. Forests. In St. G.C. Cooper, and P.R. Bacon, editors, Edward Arnold, London: The Natural Resources of Trinidad and Tobago.
Davis, S.D., S.J.M. Droop, P. Gregerson, L. Henson, C.J. Leon, J. Villa-Lobos, H. Synge, and J. Zantovska. 1986. Plants in danger: what do we know? Gland, Switzerland and Cambridge, UK.: IUCN.
ffrench R. 1991. A guide to the birds of Trinidad and Tobago. Ithaca: Cornell University Press.
Huber, R. M., and R. Meganck. 1987. National parks of Trinidad and Tobago. Naturalist 7(3): 629.
IUCN. 1992. Protected areas of the world: a review of national systems. Vol. 4: Nearctic and Neotropical. Gland, Switzerland and Cambridge, UK: IUCN.
Kenny, J., P. Comeau, and L. Katwaru. 1997. A survey of biological diversity, Trinidad and >Tobago. United Nations Development Programme, Port of Spain.
Republic of Trinidad and Tobago. 1990. Trinidad. Map at scale of 1:150,000. Lands and Surveys Division, Ministry of Planning and Mobilization, Port-of-Spain, Trinidad.
Stoffers, A.L. 1993. Dry coastal ecosystems of the West Indies. In E. van der Maarel, editor, Ecosystems of the world 2B: dry coastal ecosystems Africa, America, Asia and Oceania. B.V., Amsterdam: Elsevier Science Publishers.
Thelen, K.D., and S. Faizool. 1980. Policy for the establishment and management of a national park system in Trinidad and Tobago. Technical Document Forest Division/OAS Project.
Prepared by: Sean Armstrong
Reviewed by: In process