Flora

The flora currently found on Mauritanian territory is very diverse and varies from one region to another. There are major differences between groups in the North and those in the South. These differences are essentially due to rainfall variations. Indeed, going from North to South, we go from a Saharan region more or less influenced by the ocean towards a more humid Sahelian region.

The flora of Mauritania as a whole has no particularities compared with that of neighboring countries. However, unlike these countries, the identification of all the species and the knowledge of their distribution are not satisfactory. The study of flora is, however, of considerable interest, for it is very varied in its systematic composition and brings together very different geographical elements which pose problems of the first order.

Mauritanian flora is represented by 115 families (JP Barry & Celles 1991), 99 families (Lebrun JP 1998) which are of unequal importance. It contains about 550 genera (JP Barry & Celles 1991), 443 genera (Lebrun JP 1998). .6% to 47.3% of the species according to the authors meet in four families (Poaceae, abaceae, Asteraceae and Cyperaceae).

more than half of the species come together in twelve families:

(Poaceae, Fabaceae, Asteraceae, Cyperaceae, Euphorbiaceae, Malvaceae, C Cyperaceae, Euphorbiaceae, Malvaceae, henopodiaceae, Convolvulaceae, Convolvulaceae, Amaranthaceae, Mimosaceae, Capparidac Arnaranthaceae, Mimosaceae, eae), the other families include few genera or are monogeneric (56 Families) or even mono specific (30 Families).

Thus, Poaceae occupy the first place in terms of number of species followed by Fabaceae and Asteraceae respectively, while if we consider leguiminoseae (Fabaceae, Mimosaceae, Caesalpiniaceae) as a family, they come as a family , in second position (47genera129species) after the Poaceae.

The relative importance of families varies from North to South. The desert environment (in the north of the country) produced a general impoverishment but very unevenly marked from one family to another. Going from North to South, we notice a decline in the Mediterranean affinity families, while the tropical affinity families gradually increase.

The generic coefficient which expresses the ratio of the number of genera to the number of species is approximately 50 genera for every 100 species (i.e. 2 species per genus). The high value of this coefficient denotes the poverty of this flora which is however richer than that of the Generic classification, i.e. the classification of the genera in descending order of the number of species which represent them for the genera containing more of 10 species is as follows:

The genera represented by more than 10 species are very numerous to compare with those of the Sahara which hardly exceed 3. It should be noted that nearly 60% of the genera are monospecific and that the richness of the genera varies from one region to another. . from one region to another .

The biological spectrum of Mauritanian vegetation is very significant. It brings out the superiority of the class of therophytes compared to the others. This predominance of therophytes highlights the reality of the country which is characterized by long periods of characterized by long periods of drought and jointly extremely low and localized rainfall. Low and localized presence. The presence of a fairly large proportion of chamaephytes and phanerophytes indicates that the ecological conditions are not as unfavorable as one might think at first glance, which gives the country an attenuated tropical character. country an attenuated tropical character.

In general, the decisive factor influencing the density of vegetation in Mauritania is water. The temperature does not have a decisive influence since it always remains within the since it always remains within the acceptable if not optimal limits.

The break between the holarctic and paleotropical empires passes through the Adrar. Thus Mauritania appears as a territory with its own individuality. It is a transition zone between two regions, one dry in the north and the other more humid in the south. In reality the limits between the zones are not clear and brutal. Going from one zone to the other, we pass through intermediate zones.

The flora of Mauritania includes a Saharo-Arabic element largely predominant in the north and a Sudano-Angolan element which increases as one progresses towards the South where it becomes largely dominant; to these two elements are added Mediterranean/Saharo-Arabic linking elements and Saharo-Arabic/Souclano-Angolan linking elements in addition to multi-regional elements.

Author: Ahmedou Ould Soule Professor and Researcher at the Ecole Normale Supérieure de Nouakchott

Title: Trees, shrubs and shrubs of Mauritania and their uses

zip download