Biology Reference
In-Depth Information
facing slopes, on the western end of the islands, and on serpentine and
coarse soils that create physiologically dry habitats. In some areas it is ex-
panding from aridifi cation due to abusive land use followed by abandon-
ment of the land, while in others it is contracting because of construction,
local cultivation, and the gathering of wood down to barren ground, but
almost everywhere it is being modifi ed toward near desert.
There are no natural grasslands in the Antilles, and oak and pine sa-
vannas are the result of longtime land use. The coasts are bordered by
mangrove and beach/strand/dune ecosystems, and inland there are fresh-
water herbaceous marsh/swamp/bog, and aquatic communities. The larg-
est swamp in the Antilles is on the south coast of Cuba at Cienaga de
Zapata. One part is familiar as the Bahía de Cochinos, the Bay of Pigs.
The swamp fl uctuated greatly in size during each of the roughly eigh-
teen to twenty glacial/interglacial intervals of the Pleistocene, when, for
example, lower sea levels repeatedly enlarged Cuba by half, primarily
from exposure of the southern coastal plains. High sea levels, as at pres-
ent, temporarily bring back the modern confi guration of Cuba, but the
expanded version is typical of about 90 percent of the past 2.6 million
years.
There is no lowland tropical rain forest in the Antilles, although the low-
est wet phase of the lower to upper montane broad-leaved forest formation
is similar. This formation covers an extensive area around El Verde in the
Luquillo Mountains of eastern Puerto Rico. Upslope on the Dominican Re-
public, there is a coniferous forest of
Pinus caribaea
, used for the manufac-
ture of paper pulp, and
P. occidentalis
, the pine on Pico Duarte, the highest
point of land in the Antilles at 3098 m. On other highlands, there is an elfi n
or cloud forest. There is no páramo, but some physical features on Pico Du-
rate are reminiscent of cirques and moraines that possibly indicate former
limited glaciation.
All these geologic and climatic events and the resulting geomorpholog-
ical features document a dynamic past for the islands of the Caribbean.
They drove the processes of biotic evolution and migration that over a
45-million-year period have created the seven modern ecosystems of the
Antilles: shrubland/chaparral-woodland-savanna (the last resulting mostly
from human activity), mangrove, beach/strand/dune, freshwater herba-
ceous bog/marsh/swamp, aquatic, lower to upper montane broad-leaved
forest, and coniferous forest.
