Floristic and ecological monitoring on a store-and-release cover in arid and semi-arid environment of Kettara mine, Morocco

The Kettara abandoned mine, Morocco, is a highly acid drainage-generating site with negative impacts. In order to impede the water–oxygen migration within tailings of Kettara mine, a store-and-release (SR) cover made with phosphate mine wastes (PMW) layers was implemented on the tailings of Kettara mine in five experimental cells. The characterization of vegetation is an important aspect of the monitoring strategy for the SR cover. In this optic, the objective of this study was to follow the local flora dynamic on the SR cover. Furthermore, this research highlighted the potential of this flora for the development of other appropriate phytomanagement plans of mining wastes. The monitoring surveys were carried out over five years (March 2015–April 2019). Six permanent transects were placed on five-constructed cells. The method of Line Intercept Transect was used to evaluate the vegetation cover and to determinate the floristic composition and relative frequency of the species. Plant diversity was quantified by Shannon diversity (H′) and Pielou evenness (J') indices. Four functional groups of plants were identified; therophytes and chamaephytes were the most abundant. Among 19 recorded families on SR cover, the most widely represented were Compositae (26.83%), Leguminosae and Poaceae with 9.76%, Apiaceae and Brassicaceae with 7.32% of the total taxa for each one of them. Of the 39 identified vascular species on SR cover, the most abundant were Anacyclus valentinus L., Calendula arvensis M.Bieb., Emex spinosa (L.) Campd., Hirschfeldia incana (L.) Lagr.-Foss., Spergularia rubra (L.) J.Presl & C.Presl, Stipa capensisthunb, and Herniaria cinerea L. Significant differences in Shannon diversity index (H′) were observed between the sampling areas (p > 0.05), it ranged from 0.739 to 3.857 bits/ind. on SR cover. The Pielou evenness index was not significantly different through transects; it varied from 0.578 to 0.978. These values indicated an equitable distribution of individuals within species on the investigated transects. The study revealed 29 vascular plant species that represent a great potential to be promoted for the phytomanagement of mine wastes in the context of arid and semi-arid environments.