biological diversity and tropical forests in tunisia - PART

3.4. Tucisiac Dorsal
The Tanisian Dorsal is the northeastern extensioc of the Atlas
mouctaics, which begic ic Morocco, pass through Algeria and enter Tunisia
at Bou Chebka, 35 km west of Kasserice. Guecod and Schoececberger (1965)
cocsidered the Tacisiac Dorsal as including the peaks of Djebels Chambi,
Semmama, Tiouacha, Barbrou, Serdj, Bargou, Fkirine and Zagouan, whkch are
oriected fairly regularly SW-NE. In this documect the Tucisiac Dorsal
will be considered as including the above mentioned 'backbone' ridge and
the adjacect moantaics, such as Djebels Bireno, Serraguia, Oum Jeddour,
Krhila, Trozza, Ousselat, and Macsoar. The range also extends beyocd
Djebel Zaghoaac to Cap Boc and includes Djebels Ressas, Bou Komine and
Sidi Abder Rahmace. As the mountains extend northeast they gradually
decrease in altit~de. Djebel Chambi ic the southwest is Tucisia's highest
poict at 1544 m while Dj. Sidi Abder Rahmane in the cortheast has a
maximum altitade of ocly 637 m.
The Tucisian Dorsal is composed primarily of calcareoas rmk. Soils
are si~ilar to those of the High Tell - calcimorph with macy deposits of
seed, gypsum acd marccz. Hot, dry sammers ar.d stormy precipitatioc
pattercs make the area especially vulcerable to erosioc. Kacy of the
sozth slopes are severely eroded acd sediment loads ic rivers are high.
The three most important rivers origicaticg ic the racge are the Oueds
Nebhara, Eargselil (El ~erd) acd Zeroud (El ~atob) all of which flow into
Sebkhet Kelbia (section 3.3.2.4).
Domicact forest species of the Tucisian Dorsal are holm oak acd aleppo
pice ic the soathwest acd cecter, to which are added thuya Callitris
articulata acd kermes oak ic the cortheast. Holm oak ofter. grows as a
maquis 2-3 m tall or. mouctaic sammits or as ac understory in aleppo .- pine
~
forests or browc calcareous soils. Juniperus phoenicea is commoc ic the
ucderstory of aleppo pice oe poorer soils and at lower elevations. It
becomes the characteristic species ic degraded stands.
3.4.3.1. Djebel Chambi
Fifteec kilometers west of Kasserine is Dj. Chambi, essectially the
first high peak of the Tucisiac Dorsal as it enters from Algeria. From a
summit altitude of 1544 m, Chambi drops to 565 m altitude at the base.
Along with the typical substrates of the Tucisian Dorsal there are also
deposits of zinc, galeca, hematite (iron ore) and traces of coal ic the
Chambi massif (~ir. For. 1981 ).
The climate at Chambi is somewhat different from nearby Kasserine,
sicce the precipitation rate increases 20 mm for every 100 q increase in
altitade. Therefore the relatively dry plaics (semi-arid superior)
contrast greatly with the Subhumid summit, which receives 12.500 mm annual
precipitatioc ic the form of raic, hail and sr.ow with additional moisture
from clc~zds acd fog.