Flore

La flore présente actuellement sur le territoire mauritanien est très diversifiée et varie d'une région à l'autre. Il existe de grandes différences entre les groupes du Nord et ceux du Sud. Ces différences sont essentiellement dues aux variations des précipitations. En effet, en allant du Nord au Sud, on passe d'une région saharienne plus ou moins influencée par l'océan vers une région sahélienne plus humide.

La flore de la Mauritanie dans son ensemble ne présente aucune particularité par rapport à celle des pays voisins. Cependant, contrairement à ces pays, l'identification de toutes les espèces et la connaissance de leur répartition ne sont pas satisfaisantes. L'étude de la flore présente cependant un intérêt considérable, car elle est très variée dans sa composition systématique et rassemble des éléments géographiques très différents qui posent des problèmes de premier ordre.

La flore mauritanienne est représentée par 115 familles (JP Barry & Celles 1991), 99 familles (Lebrun JP 1998) qui sont d'importance inégale. Il contient environ 550 genres (JP Barry & Celles 1991), 443 genres (Lebrun JP 1998). 0,6% à 47,3% des espèces selon les auteurs se réunissent en quatre familles (Poacées, Abacées, Astéracées et Cypéracées).

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.

La flore de Mauritanie comprend un élément saharo-arabe largement prédominant au nord et un élément soudano-angolais qui s'accroît au fur et à mesure que l'on progresse vers le sud où il devient largement dominant ; à ces deux éléments s'ajoutent des éléments de liaison méditerranéens/saharo-arabes et des éléments de liaison saharo-arabes/souclano-angolais en plus des éléments multirégionaux.

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

Titre : Arbres, buissons et arbustes de Mauritanie et leurs usages

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