Exclosure area decreases the spread of the invasive plant Senna obtusifolia (L.) and enhances forage value of Sahelian rangelands

Background Sahelian rangelands constitute the main source of livestock feeding but are continuously degrading due to the climate change and human pressures. This degradation has led particularly to the invasion of rangelands by the less palatable plant species called Senna obtusifolia . This study aimed to restore the degraded Sahelian rangelands through grazing exclusion on herbaceous vegetation initially invaded by Senna obtusifolia . Methods Plant species composition, species diversity, aboveground biomass, density, height, and cover rate of the herbaceous vegetation were monitored across plots with different invasion levels over four consecutive years. Pastoral value was assessed using an index of specific quality of each species of the herbaceous vegetation. Results We found that aboveground biomass, plant cover, and species diversity of companion species decreased significantly (P < 0.05) with the levels of Senna obtusifolia invasion. During the monitoring period, aboveground biomass, density and height of the invasive plant Senna obtusifolia progressively decreased in the fenced plots. In contrast, similar floristic attributes of the companion species increased (88%). Indeed, species with low or no pastoral value were significantly (P < 0.05) less abundant than those with medium and high pastoral value throughout the four years monitoring time. Conclusions Our findings highlight how exclosure simultaneously contributes to restore the herbaceous vegetation of Sahelian rangelands while controlling the proliferation of Senna obtusifolia . Sahelian rangeland management systems that include at least four years of exclosure before opening to grazing are an effective solution to control the spread of the less palatable and plant invasive species Senna obtusifolia.