Rainforest

I have never seen anything so beautiful. The country around the river is full of trees, beautiful and green and different from ours, each with flowers and its own kind of fruit. There are many birds of all sizes that sing very sweetly, and there are many palms...

 

log of Christopher Columbus 
for Sunday 28 October1492 
(in Cuba)

 

Pristine coastline of Dominica

                            
 

The term tropical rain forest was coined by the German explorer Schimper in his classic text (1898) Plant Geography.  He gave this definition for rainforest - "Evergreen, hygrophilous in character, at least 30 m high, but usually much taller, rich in thick-stemmed lianes and in woody as well as herbaceous epiphytes". Others have noted the species richness of the rainforest community.

Rainforest, as the name suggests, relies on an abundance of water such that it is largely limited to the humid tropics, i.e. equatorial regions. In the Caribbean, the seasonal climate precludes rainforest in the lowlands but at modest elevations on the mountainous islands there is adequate rainfall yearound to allow such a plant community to develop. Not surprisingly this rainforest type is distinct from that found on the South American continent.



Rainforest

The rainforest of the Caribbean islands is known as the Dacryodes-Sloanea association after the two dominant trees (photos below) of the principal canopy. It is also known as submontane rainforest. The forest comprises an upper closed canopy 30 m  high, a discontinuous middle tree layer at 20 m and a low storey of small trees at 10 m.Gommier (Dacryodes excelsa) is the dominant tree and is joined in the uppermost layer by, among others, several species of chataignier ( Sloanea spp.) with their large plank buttress roots.  Bois côte (Tapura antillana) is the commonest tree of the middle layer while the swizzle stick tree (Quararibea turbinata) is a common understorey species. Members of the coffee family are common in the shrub layer but also present may be tree ferns as well as palms such as the macaw palm (Aiphanes minima). On the branches and trunks of the lowest trees are found epiphytic ferns, bromeliads and aroids (e.g. the bird nest anthurium - Anthurium hookeri). There may be a sparse herb layer with the fern ally Selaginella flabellata, a Lesser Antillean endemic. There are woody vines or lianas which are rooted in the ground and climb and spread in the canopies. The rainforest trees tend to have largish leaves and are without spines. The undergrowth of shrubs, herbs and saplings is usually easy to penetrate. 


Rainforest at Grand Etang, Grenada.

Buttress roots of chataignier (Sloanea sp.)

Bird nest anthurium (Anthurium hookeri) growing epiphytically 

The forester John Beard in his classic (1949) Natural Vegetation of the Windward & Leeward Islands points out some 40% of the tree species are endemic to the Lesser Antilles and many of the others are natives with a wider distribution (e.g. endemic to the Lesser Antilles and northern South America). Our improved knowledge of regional flora would suggest a slighter lower figure of  30% for rainforest trees that are Lesser Antillean endemics. Few if any introduced species have become naturalized in this plant community. Not surprisingly, these Lesser Antillean endemics are especially centred on the four older islands of the archipelago, Guadeloupe, Dominica, Martinique and St Lucia.  In the Easter Caribbean, rainforest is limited to the high volcanic islands.

Where this forest is cleared, vegetation dominated 
by the tree ferns Cyathea arborea and 
Cnemidaria grandifolia
 is the first to develop. 
This is termed Tree fern brake.
Enjoying the thirst-quenching sap of a rainforest 
liana called liane chasseur - St Lucia  


The two dominant trees...
Gommier (Dacryodes excelsa) trunk exuding latex
 which is used as incense 
Chataignier (Sloanea sp.). Note the white cap and t-shirt of the guide for a sense of scale!

Environmental factors

This forest occurs in the wet zone (> 1800 mm / 70 " rainfall annually) and, although there is still a period of reduced rainfall, there is always an excess of water supply over demand such that there is effectively no dry season. It lies typically at 300 -750 m and in Dominica may receive annual rainfall of 4000-7500 mm (170-300")!
 

Animal life
A wide range of bird species, most notably single island endemic parrot species on several islands. Also agouti, opossum, boas and other snakes, bats, crabs

 

 

Poster produced by Dominica's Forestry, Wildlife & Parks Division depicting the endemic Sisserou (Amazona imperialis


Which other Lesser Antillean islands have already lost their parrot species?

Caribbean Vegetation Mapping Project Equivalent
I.A.1.N.b. Submontane tropical or subtropical rain forest 
I.A.1.N.b. Dacryodes excelsa - Sloanea massonii Forest Alliance (Dacryodes excelsa - Sloanea massonii submontane rain forests) I.A.1.N.b. Dacryodes excelsa - Sloanea massonii Forest Alliance (Dacryodes excelsa - Sloanea massonii submontane rain forests)

 

 

 

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This site was last updated on 29 October, 2013.
Sean Carrington 2002
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