biological diversity and tropical forests in tunisia - PART

C. Influences
During the successive periods of control by various nations through
history, several vegetatioc degradation and regeneration cycles have
occurred on Zembra. Degradation of the climax vegetation types by
cultivatior, grazing, burnicg acd woodcutting encouraged invasion by more
xeric species and eliminated some less xeric species (~nane 1977). The
prolonged human activity resulted in the evolutkon of the present shrub
communities acd the absence of oaks, which would otherwise be the climax
forest type of the island.
After 1900 agriculture and population pressure decreased, but
occasiooal fires continued. After 1963 tourism began to increase. By
1977 tourist use had only reached the lowest part of the alluvial platn,
but the effects were great enough to decrease speckes diversity. On steep
slopes where the vegetatioo cover is inadequate, the erosion rate equals
the soil formatioc rate. Human interference accelerates the soil loss.
To protect this unique and internatiocally important natural area the
ectire archipilago and a 1.5 mile marice zone were designated as Tunisia's
first catiocal park and biosphere reserve in 1977. Plans for tourism and
protsctior acd echaccemect of the fauna and flora were made, but very
little has beer implemected, largely due to the fact that the island was
later placed under military coctrol.
3.2. Kuriate
The Kariate islacds ari two relatively small emergences E-NE of
Monastir and E-SE of Sfax. The main island is aboxt 2.5 km long by 2 km
wide, with an area of about 350 ha. It lies 16 km from the mainland
(~ocastir) and 2 km from the smaller island. The small island is ocly
abodt 100 ha in size - much of which is ictertidal flats and lowland.
Liki thi mairland at Sousse, to which the islands were once connected,
Kuriate is formed of a limestone substrate overlaic by calcareous and
sandstori crusts topped by a thin layer of sand deposited by the sea. The
islands are low and flat - always less than 10 m ASL and usually only a
few meters above sea level. The sea bottom slopes very gradually away
from the islacds and does not reach 50 m depth until more than 10 km out
to sea.
A. Vegetatioc
Approximately one-third of the main island ia a low sebkhet-like
deprissioc with an outlet to the sea. The center of the depression is a
few hectares of bare sand surrounded by a haolphile association of
Arthrocnemum acd Halocnemum. On higher ground, dominant plants include:
NAS Limociastrum guyociacum Euphorbia paralias
Pistacia lectisc~s Frankexka sp
Crataeg~s azarolus Tamarix sp.