Abstract:

Temporary ponds play substantial roles in preserving biodiversity in the Sahel. This study investigated the influence of anthropic and eco-hydrological factors on the plant diversity around two grazed ponds and one ungrazed pond in Ferlo, northern Senegal. Two phytoecological transects were established per pond. On each transect, homogenous herbaceous vegetation units were identified and characterized (herbaceous cover, exposure, soil texture, soil moisture and pH, average height and slope). The herbaceous flora comprised 55 species, 41 genera and 22 families across the three ponds. Species of the Poaceae, particularly Eragrostis tremula and Enteropogon prieurii, mostly colonized the grazed ponds, while the ungrazed pond favored other families’ species such as Achyranthes sp., Commelina forsskaolii, Corchorus sp. The Shannon’s diversity index (H′) of Wendu Marodi (ungrazed pond) was slightly higher (4.9 bits) than that of Belel Lougal and Belel Sow (grazed ponds) with 4.8 and 4.5 bits, respectively. The equitability indices were relatively high in the three ponds (0.85, 0.83 and 0.78). Eco-ecological factors distinguished four species’ groupings: a Tribulus terrestris grouping colonizing the constraining and over-grazed zones, a Digitaria horizontalis grouping, and Chloris barbata grouping found in the transition zones, and an Achyranthes aspera grouping in the wetlands, where woody plants were strongly present and the anthropic action low. This study highlighted the importance of maintaining a landscape mosaic of ungrazed or semi-protected ponds and grazed ponds to preserve the herbaceous floristic diversity in the center of Ferlo (Senegal) and the Sahel in general.

Key words: ponds, Ferlo, grazing, herbaceous vegetation, transect