Options for Reclamation of Mine Tailings in West Africa
Revegetation of tailings in West Africa presents two major problems when using established methodologies, in that soils have the potential to be highly alkaline, rather than acidic, plus the majority of recommended plant species are non-native to the area. Alteration of cap engineering however can modify hydrology, pH and morphology, allowing for a variety of habitats. Cover crops are often deep rooted, so may impact the capillary barrier, requiring possible modification in the depth of sub-soil and selection of species. Conversely, deep-rooted species are appropriate in avoiding erosion in sloped margins. Although some pioneer species, such as vetiver grass and Prosopis sp. are non-native, local species of this genera exist and should be trialled to establish both usefulness and invasiveness. Alkaline soils tend to suffer from nutrient deficiency. However, these can be suitable for savanna vegetation, with leguminous shallow-rooted shrub species providing available nitrogen. Succession to such a community can provide long-term stabilisation of biomass. Use of local species is preferable but local seed should be treated as a rare resource. Management regimes, such as burning, grazing and hand-pulling should be trialled and subsequent changes made, as required, to promote stability and biodiversity. This may also provide a suitable regime for growth of long-term crops and biofuels.