Evaluation of the phytocenotic potential of the Southern-Central African copper outcrops with a view to phytoremediation of polluted site by mining activity | Evaluation du potentiel phytocenotique des gisements cupriferes d'Afrique centro-australe en vue de la phytoremediation de sites pollues par l'activite miniere

Data regarding different characteristics (climatic, geological, pedological, botanical (floristic, phytosociologic, evolutionary), phytogeochemical and ecosystemical) of Southern-Central African cupriferous outcrops as well as information concerning relations existing, yesterday and today, between Man and copper outcrops through mining activity and phytoremediation have been knowledgably summarised. This knowledge having been acquired, the methodology suitable for the phytocenotic potential assessment regarding one copper site prior to its possible mining has been set up. Previously, a set of information concerning firstly cupriferous outcrops (inventory, distinction of three metallogenic provinces, alteration intensity regarding the original vegetation, botanical prospecting effort) and secondly cupricolous flora (inventory, endemism, concept of taxa with high phytochemical potential) is provided. It transpires that, as far as the recently prospected "anomalies" are concerned, and according to the metallogenic provinces involved, a large proportion of orebodies offers an original vegetation, partially altered, or totally destroyed. The pollution forms observed have been listed. The extremely detailed study of the cupricolous taxa within the genus Buchnera L., as well as the description of a new species, Crotalaria cupriaila Leteinturier, are presented. Taken as a whole, the study of an ecological unit concerns two components, namely soil and vegetation. The study of several copper outcrops allows us to put this methodology into practise. Its application was also extended to a lead-zinc outcrop located in the same area. Management measures regarding threatened species by mining activities are suggested. Next, revegetation tools for damaged sites are proposed : the resort to the ecologic groups' concept on the one hand and to taxa particularly suitable for phytostabilisation on the other. Finally, in situ and ex situ experiences regarding cuprophytes germination and growth have led to pinpoint a number of taxa interesting for their vitality regarding phytoremediation.