Flora of Dominica, Part 2 - Smithsonian Institution Libraries

2 SMITHSONIAN CONTRIBUTIONS TO BOTANY
(1979), David’s winds reached 240 km/hr (150 miles/hr),
damaged 80% of the forests, destroyed 100% of the banana
crop, felled or defoliated 95% of the coconut trees, and left 70%
of the population homeless.
VEGETATION
The following key (from Hodge) is basically physiognomic
and defines seven communities (woodlands, forests). It should
be recognized that these communities intergrade and that the
key defines well-developed communities. Two communities
keyed out by Hodge have been dropped, Semi-evergreen
Forests and Lower Montane Forests. The former is transitional
between Deciduous Forests and Evergreen Forests. The latter is
transitional between Evergreen Forests and Montane Forests.
It should be noted that the key assumes that humans have not
made changes. In many cases, human influence creates
different communities of secondary or weedy nature that are, in
effect, modifications of the otherwise primary, undisturbed
communities that are keyed out.
Key to Major Plant Communities on Dominica
1. Tree growth c10 meters high.
2. Trees microphyllous, often thorny , . . . 3. Dry Scrub
2. Trees normal-leaved, rarely thorny,
3. Windswept seashore with few epiphytes . . . . . . .
. , . . . . . . . . . . . . . . . , . . . . -2. Littoral
3. Windswept mountain summits and ridges with many
epiphytes . , . . , . . . . , , , . . , . . . 7. Evn
1. Tree growth >10 meters high.
4. Deciduous trees forming >25% of top stratum
. . . . . . . . . . . . . . . . . , . , . . 4. Deciduous
4. Forest evergreen (45% of top stratum deciduous).
5. Inundated with fresh water . . . . . . . . 1. Swamp
5. Non-inundated forest with continuous canopy >20 m
high.
6. Trees in 3-4 strata; dominants A0 m; leaves
mostly compound . . . . . . . . . .5. Rainforest
6. Trees in 2 strata; dominants c40 m; leaves mostly
simple . . . . . . . . . . 6. Montane Rainforest
The following discussion proceeds from the lower to higher
elevations.
1. Swamp Forest: This community is very localized because
of the lack of extensive low swampland. In its climax form it is
dominated by Pterocarpus officinalis, as along the Indian River
oust south of Portsmouth) and near the beach along the north
coast.
Secondary (disturbed) swamp forests, such as that of the
Cabrits Swamp, are dominated by Annona glabra and
Chrysobalanus icaco and grade into sedges, a fern (Acrostichum
danaeifolium), and, sometimes, an erect, thorny mid
(Montrichardia arborescens). A few mangrove plants have
recently been found in the Cabrits Swamp, the first record for
Dominica.
2. Littoral Woodland: Along the windward (Atlantic) coast
is a narrow belt of shrubby woodland that is constantly swept
by winds and salt-spray “training” branches down-wind. The
dominants are Coccoloba uvifera (raisin-bord-de-mer),
Chrysobalanus icaco (z’icaque), and Erithalis fruticosa (bois
chandelle) .
Elsewhere on the island, beachs have such pioneers as
Ipomoea pes- caprae (beach morning-glory), Canavalia rosea
(horse-bean), and Vigna luteola, not to mention the ubiquitous
Chrysobalanus icaco, Coccoloba uvifera, and Thespesia
populnea. In a few locations, such as Scotts Head in the
southwest comer, Hippomane muncinella (manchineel) occurs.
It has a virulent, miky sap that causes severe reactions on
contact.
3. Dry Scrub Woodland: Between the seashore and the
inland rainforests along the leeward (Caribbean) coast, there is
a low tropical woodland characterized by microphyllous,
deciduous, often thorny species. This is well developed on the
Cabrits, Morne au Diable, Scotts Head, and Pointe Ronde. This
woodland is in leaf from June to January and “naked” from
March, the beginning of the flowering season. Flowering ends
by May and new vegetative growth begins.
No other area has so many showy-flowered species,
including such legumes as yellow Haematoxylum campechianum
(logwood), red Sabinea carinalis (bois Carib, endemic to
Dominica), pink Calliandra tergemina, and purple
(Lonchocarpus benthamianus). One of the notable trees is
Bursera simaruba (gommier rouge) with reddish exfoliating
bark. A characteristic vine is yellow Stigmuphyllum puberum,
also red-and black-seeded Abrus precatorius (crab’s eyes), and
prickly Mimosa casta. True epiphytes are restricted to
Ti1 landsia .
Much of the Dry Scrub Woodland has gone to crops and
grazing, resulting in a predominance of weedy grasses
(Panicum, Paspalurn, and others), sedges, and legumes
(Crotalaria, Desmodium, etc.). Other prominent genera are
Lantana, Euphorbia, Phyllanthus, Sida, etc.
The Grand Savanne (Grande Savane), midway on west coast
above Salisbury, is probably the island’s most recent lava flow.
It is a 1 square mile (2.59 km2) expanse of grasslands and open
scrub. Fires and shallow, extremely porous soil Seem to control
its open aspect. The sea-cliffs have a number of interesting
plants, including Cactaceae, Agave, brilliant red-flowered
Pitcairnia gracilis, and even the rare and primitive fern ally,
Psilotum nudum.
4. Deciduous Forest: This community is transitional
between the lower Dry Scrub and the higher Evergreen
Rainforest. Hodge notes that some of the “index” species, such
as the palm Rhyticocos amara and large-leaved Coccoloba
venosa, also occur on the windward (Atlantic) side, unlike the
species of the m e Dry Scrub. Hodge also refers to this as a