Invasiveness of two exotic species, Chromolaena odorata (Asteraceae) and Hyptis suaveolens (Lamiaceae), in relation with land use around Bétécoucou (Bénin).
Very few studies have been conducted on the effects of farming systems on the invasive capacity of exotic species. This study fills this gap by analysing the invasive capacity of two exotic species, Chromolaena odorata and Hyptis suaveolens, in farming systems in the Guineo-Congolian/Sudanian transition zone of Benin. The findings show that the annual seed yield of C. odorata (45 151 seeds/plant) is significantly higher than that of H. suaveolens (1 782 seeds/plant). On the other hand, seed germination rate of H. suaveolens (70%) was higher than that of C. odorata (30%). Seed production and population density of C. odorata were higher in fallows and tree-savannah than in deforested savannah and croplands. H. suaveolens seed production and population density were higher in fallows and degraded savannahs. Bush fire reduced plant growth, the amount of seeds annually produced, and the seed germination rate. This study shows that the invasion intensity is related to the farming system. These two exotic species unfavourably altered the vegetation structure available to livestock by favouring the establishment non-forage species.