biological diversity and tropical forests in tunisia - PART
biological diversity and tropical forests in tunisia - PART
biological diversity and tropical forests in tunisia - PART
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3.4.5. Douirat !4ouctaics<br />
Ic southerc Tunisia, alocg the eastern border of the Gracd Erg is a<br />
long chair of low mo~ctaics acd high plateaus. The Douirat moxtaics are<br />
orierted K-S ard racge <strong>in</strong> altitude from 300 - 600 m. Due to the iccreased<br />
altit~des, the moucta<strong>in</strong>s are slightly cooler <strong>and</strong> receive more raic than<br />
the surroacdi~g desert, but the annual precipitatioc fs still only 200 -<br />
300 mrn.<br />
Vegetatioc. Plact associations <strong>in</strong> the northern. part of the Douirat<br />
mouctaics differ from those of the south ic that the apper slopes from<br />
Katmata to Dj. Rhar el Jami (NM of ~ataou<strong>in</strong>e) are vegetated by degraded<br />
Junipens phoenicea garrigues. Juniper is scarce on most of the mozctaics<br />
ard may soon disappear completely. Other species of the assocjatioc<br />
(ORSTOE 1962) icclude scattered :<br />
Ceratocia siliqaa Rhas tripartitam<br />
Olea earopaea oleaster Periploca laevigata<br />
Pistacia atlantjca Calycotome villosa<br />
acd, nore commorly, thermophiles acd calcicoles:<br />
acd other species, sach as:<br />
Tescriam polium Phagnalon saxitile<br />
Rosmaricus officicalis Cistiis libacotis<br />
Globiilaria alypum Fumaca thymifolia<br />
Thymus capitatus Gynnocarpos decarder<br />
T. hirtus Heliacthemum kahiricum<br />
Coris monspeliecsis H. ruficor~m<br />
Atractylis serratuloides Stipa parviflora<br />
Gecista microcephala Herriaria foctacesii<br />
Or the lower slopes acd on the moxta<strong>in</strong>s to the south, the vegetatioc<br />
grozps irdicate fbrther degradatioc. The associatior of Arthrophytum<br />
scoparian acd Artemisia herba-alba, Stipa tecacissima variart also<br />
cortairs:<br />
Tetrapogor villosus<br />
Percisetum elatum<br />
Hyparrheria hirta<br />
Farsetia aegyptiaca<br />
Moricacdia arvecsis<br />
Ac overexploitation of the esparto grass ard other vegetatioc has<br />
reszlted <strong>in</strong> a vegetatioc stage characterized by the abardacce of:<br />
Gymcocarpos decarder Helianthemirm kahiricun<br />
Herciaria f r~ticosa A tractylis serratuloides<br />
Anabasis articulata oropediorum<br />
This vegetatior stage represects ac irreversible desertificatjor process<br />
(Le Hoseros 1959 ir ORSTOM 1962). which seems to accelerate xder<br />
dem~graphic presszre .
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