biological diversity and tropical forests in tunisia - PART

Ic the southeeat, heavier soils result in Artemisia herba alba beicg
associated with jujube and combinations of esparto grass, Asparagas albas
and Globalaria alyp'im. Along the edge of the High Steppe, sosth of the
above associations and extecdin~ icto the Low Steppe is ac association of
Rhactherim Suaveolens with ~iaithus cricitus and-krtemisia canpestris.
B. Fauna
Macy of the animals found ic the mouctaics descecd icto the plairs to
feed, drick, or as part of a migration pattern. Of special icterest ic
the High Steppe are threatened houbara bustards, which cest ic the easterc
part of the regioc, and rare hyecas, which descend fron the mozctaics to
prey oc wild boar. Common fauna are listed ic Section 4 (Gouvercorats of
Sidi Boz Zid, Kasserice, Gafsa).
C. Icflaecces
A large paper m i l l is located ic Kasserice. Esparto grass fibers are
processed at the m i l l to produce a high quality paper. Of approximately
433,000 ha of decse esparto steppes ic Tucisia, most are ir. the High
Steppe acd more thac half are exploited for the mi 11 (~ir. For. 1986).
This exploitatior, alocg with overgrazicg acd clearicg for agric;lt"re is
having serious impacts oc the cataral vegetatioc of the regioc. Of the
124,000 ha of esparto steppe in the Sidi BO.G Zid Gozvercorat, ocly ore
third is cocsidered decse or moderately dense, acother third is sparse acd
the fical third is degraded (erosioc, fires, cultivatioc). The Forestry
Directorate has implemected regulatiocs to protect the steppes fr3s
overharvesticg, but overgrazicg and cultivatioc are problems nwh nore
difficult to coctrol. The paper plact also uses large qzactities of water
from the Osed Derb acd releases vario2s chemical compovcds ic its
discharge.
3.5.2. Low Steppe
East of the High Steppe, north of Sebkhet Mecheqzig~e acd sovth of
Ecfida, a vast flat to gectly ucdulaticg plaic extecds to the coast.
Throzgh~zt the Low Steppe, the altitade is less thac 250 m. Rscoff from
the High Steppe flows ic several temporary rivers acd settles ir the macy
depressiocs ic the Low Steppe, creaticg sebkhets (~ectioc 3.3.2). Shallow
soils form or. calcareous crusts throzgh much of the region, ard ic areas
of higher precipitatioc, red Hedjterraceac soils form on hard limestone
(ONUPAA 1 985 ) .
Most of the Low Steppe receives 200 - 300 nun accual raicfall, bzt the
area soath of Sfax receives less thac 200 mm. Average temperatares of the
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regioc are cear 19 C. Bioclimates vary from Semi-arid Icferior cear the
coast to Arid Inferior southwest of 51 Djem. Eost of the iclacd portion
of the Lox Steppe has ac Arid Saperior bioclimate ( ~ Hozeroz e 1966).