Ecologia Mediterranea

elong to two major geomorphological habitat
types: small wadis that cut their way down
djebel (mountain) slopes and large wadi beds
in valleys at low altitude (800 to 1200 m).
Climatic characteristics
The Ahaggar is under the influence of two climatic
regimes: a Mediterranean regime from
the north and a tropical one from the south.
The climate of the study area is characterised
by low and irregular rainfall (Daget & Djellouli
1992). The mean annual rainfall calculated
over a period of 63 years was 46.6 mm.
The desertic character of the climate is clearly
illustrated by the ombrothermic diagram (Figure
2). Temperatures are characterised by very
high daily thermal amplitude, frequently
reaching 35 o C (Dubief 1959). The mean temperature
of the hottest month does not exceed
35 o C while mean minimum temperatures can
be as low as – 5 o C in winter.
Sampling strategy
During the sampling period, between 1990
and 1992, 190 relevés were recorded from the
different plant communities of the Tamanrasset
region applying the Braun-Blanquet
method (Gehu & Rivas Martinez 1981). Sampling
strategy was based on quadrats recorded
on floristically and geomorphologically
homogeneous sites (Benhouhou et al. 2003a).
According to topography, quadrat surface has
varied in previous studies in desertic regions
between 100 m 2 and 1000 m 2 (Abd El-Ghani
& Amer 2003; Ali et al. 2000; Benhouhou et
al. 2003a; Bornkamm & Kehl 1990;
Brinkmann et al. 2009; Fossati et al. 1998;
Hegazy et al. 1998). For our sampling set, we
chose to use a standard relevé size of 200 m 2
as applied in the Ahaggar by Quézel (1954).
Topography, soil texture and altitude were the
main determinants for the choice of sampling
sites: gravelly wadis, sandy wadis, smaller
affluent wadis, outwash zones, mountain
slopes with boulders and crevices. Our sampling
sites are located north-east, north-west,
south and south-west of Tamanrasset in the
wadis of the following massifs: Ahléheg,
Adrar Heggueghene, Ti-n-Tourdi, Tahelgha,
Touf Admer and Alemeda (Figure 3).
ecologia mediterranea – Vol. 38 (2) – 2012
Data analyses
Plant communities in the Tamanrasset region, Ahaggar, Algeria
Figure 2 – Ombrothermic diagram of Bagnouls and Gaussen
for the Tamanrasset station for the period 1970-2008.
Numerical analysis applying ordination techniques
to reduce the complex data set and
seek major ecological gradients responsible
for floristic variation is widely used in stud-
Figure 3 – Main wadis, sampling sites and localisation of the six identified
plant communities in the region of Tamanrasset.
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