Moroccan Journal of Agricultural and Veterinary Sciences

Vol. 9 No. 2 (2021): (June 2021)
Natural Resources and Forestry

Floristic study of natural formations in Vachellia tortilis subsp. raddiana in the Sahelian zone of Niger

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  • Ismael BIO,
  • Habou RABIOU,
  • Idrissa SOUMANA,
  • Boubacar MOUSSA MAMOUDOU,
  • Ali MAHAMANE
Ismael BIO Faculté des Sciences Agronomiques, Université de Diffa-Niger, Niger
Habou RABIOU Faculté des Sciences Agronomiques, Université de Diffa, Niger
Idrissa SOUMANA Institut National de la Recherche Agronomique du Niger, Niamey, Niger
Boubacar MOUSSA MAMOUDOU Faculté des Sciences Agronomiques, Université de Diffa, Niger
Ali MAHAMANE Faculté des Sciences Agronomiques, Université de Diffa, Niger

Published 2021-06-17

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Abstract

This study was conducted in the departments of Maine-Sorao and Goudoumaria located in the region of Diffa, in the extreme south-east of Niger. The objective of the study is to analyse the ecological and floristic indicators of natural formations of Acacia tortilis subsp. raddiana (Savi) Brenan. Phytosociological data were collected using the sigmatist method of Braun-Blanquet and the quadrat point method of Daget and Poissonet. A total of 80 plots were delimited. The data collected are related to the coverage of plant species and environmental variables. The spectra of biological and phytogeographic types were calculated. Hierarchical Ascending Classification (AHC), Canonical Defined Analysis (CDA) and Canonical Correspondence Analysis (CCA) were used to determine plant groupings and their ecological and floristic characteristics. The results revealed a total species richness of 61 plant species divided into 25 families and 51 genera. The most represented families are Poaceae (19.7%) and Leguminosae-Mimosoideae (11.5%). The Therophytes are the most represented biological type (59.0%). Paleotropical species is the dominant phytogeographic type (37.7%). The hierarchical ascending classification (CHA) and the Canonical Correspondence Analysis (CCA) made it possible to discriminate three (3) plant groups with A. tortilis. These are the group with A. tortilis and Echinochloa colona (G1) observed in the lowlands; the group with A. tortilis and Alysicarpus ovalifolius (G2) on the dune slopes and the group with A. tortilis and Chloris barbata (G3) on the dune flats. Analysis of diameter class structures shows a dominance of small-diameter individuals in all groups with shape c parameters of the theoretical Weibull distribution greater than 1, suggesting that A. tortilis stands are characterized by a lack of regeneration, the causes of which include fruit picking by shepherds and overgrazing. These results reveal the state of degradation and disturbance of steppe vegetation in the study areas. This study constitutes a reference state that can serve as a basis for sustainable management of the ecosystems of these areas, whose main uses are essentially pastoral.

 Keywords: Acacia tortilis, Biological types, Phytogeographic types, Floristic diversity, Niger

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References