We assessed a restoration treatment (planting tree seedlings and sowing grass seeds as nurse plants in water-harvesting half-moon pits) on degraded, compacted soils with surface crusts in Niger. Height and above-ground biomass of herbaceous plant species, tree stem circumference, and relative cover of erosive crust, gravel crust, bare ground, rock, litter, and total vascular plants were assessed at three sites with similar environmental conditions but different treatment periods (3, 5, 7 years). Species richness, evenness and Shannon-Weaver index were lowest at the 7-year site and highest at the 5-year site. Above-ground biomass of herbaceous plants and percent plant cover were lowest at the 3-year site and highest at the 7-year site. Principal components analysis revealed the change in vegetation from 3 to 7 years and spatial heterogeneity in vegetation within sites. Multi-response permutation procedures showed significant variation in species composition between the sites. Redundancy analysis showed that the temporal changes in vegetation, herbaceous plant height and litter cover were associated with a decrease in cover of erosive and gravel crusts, bare ground and rock. The 3- year and 5-year sites were dominated by annual plants, herbaceous perennials and small shrubs, while the 7-year site was dominated by annual plants and trees.
Author Name : Idrissa Soumana, Tougiani Abasse, John C. Weber, Mahamane Larwanou, Mahamane Ali & Mahamane
Keywords: Compacted soil, water harvesting systems, nurse plants, biodiversity, self-sustaining processes, resilience, Sahel.