Biology Reference
In-Depth Information
maximum on the coast of around 30
0
C and an average daily minimum on the
plateau of about 16
0
C.
This varied topography and climate has given rise to an enormous variety
of vegetation and habitat diversity, though much of the native vegetation has
already been destroyed (Lorence and Sussman,
1986
; Safford,
1997
). This
wide spectrum of native vegetation was characterized in a seminal paper by
Vaughan and Wiehe (
1937
), in which note was made of the extremely high pro-
portion of endemic and Mascarene species present in all indigenous Mauritian
plant communities. The upland regions, including the central and southeastern
plateaus and mountains above 370 m support evergreen plant habitats of five
major types. These include marsh, heath, and thicket formations, and strati-
fied climax and cloud forest. The lowland is divided into two zones. A narrow
arid zone (< 1,000 mm/year of rainfall) on the western coastal plain naturally
supported a palm savanna, and a moister zone covering the remainder of the
lowlands (1,000-2,500 mm/year) that supports several native plant commu-
nities, including dry semideciduous forests and thickets, and shrubby beach
vegetation. Forests at lower altitudes are less clearly stratified than those of the
uplands, are less dense in trees and, though still with a closed canopy, support
more growth at ground level.
Much of the indigenous, native vegetation has been cleared for plantations
or has been invaded by largely exotic species, which are rapidly supplanting
them (Vaughan and Wiehe,
1937
; Lorence and Sussman,
1986
). Depending
upon location and climate, upland forest has been replaced by guava (
Psidium
cattleianum)
, privet (
Ligutrum robustum)
and similar exotics, or by forests of
ravenala (
Ravenala madagascariensis
). Secondary regrowth in lowland areas
has produced tree savanna or thorn scrub characterized almost completely by
exotic species. Native associations have mostly disappeared, though they sur-
vive in a few isolated patches around the island. In
Figure 8.1
, we give a broad
indication of the distribution of the various vegetal types in Mauritius.
In the mid 1980s, somewhat over half of the island, some 105,000 ha was
devoted to intensive cultivation, primarily sugarcane. Savanna covered about
5,000 ha; scrub around 39,500 ha; and indigenous scrub with some tropical
evergreen formations interspersed about 8,000 ha. Indigenous natural forests
accounted for about 2,000 ha and forest plantations for a further 9,000 ha.
Other environments capable of supporting monkeys occupied a few thousand
hectares at most. Hunting plantations occupied about 28,000 ha of both forest
and savanna/scrub lands. At that time, indigenous forest covered only about 5.6
percent of the island's surface (Sussman and Tattersall,
1986
). How much this
has changed in the past 20 years is not known but these figures are similar to
those reported in le Roux (
2005
). He states that in 1999 just over 50 percent of
the land was under sugarcane cultivation and 31 percent was classified as for-
est and scrub. Lutz and Holm (
1993
) reported that between 1965 and 1985, the
