In the mountainous islands of Lesser Antilles, the climatic gradients, providing from the geomorphological patterns identify, nevertheless, a complex vegetal building, clearly noticeable throughout the physionomies and within the landscapes expressed by the great floristic unities, as well. Those latter, from the coast up to the higher peaks, anywhere sylvatic ecosystems are able to grow, are potential : tropical season, sempervirente in the average and lower levels. Tropical, submountainous and tropical mountains ombrophile in the upper levels. The lower levels, where the population settled and developped the first great plantations, suffer from an important ecosystemic degradation. The initial equilibrium being annihilated because of anthropization, within this dry bioclimate area, the regression process led to the rise of an (mainly littoral) inconstant and dry vegetation, essentially constituated by grass, shrub and pre-sylvatic phytocenoses; the forest caracteristic units are rare, secondary and present a weak biodiversity. However, within the littoral areas of this archipelago system, very organized or sub-climatic unities looking like the primitive referents, can be observed. The conclusion of studies upon those relic vegetation entities allowed primary a reconstitution of the vegetal carpet of the pre-comumbian littoral, secondary an understanding appreciation of the various and successionnal modalities, and thirdly the associated factorial constraints.
