Environmental Engineering Reference
In-Depth Information
The flora and vegetation of Luiswishi had been studied previously (Malaisse
et al.
1999
). Seventy-one taxa were listed in 1997. A new survey took place in
2001 to prospect for further metallophytes and discovered a new, unpublished
taxon of Chlorophytum (Antheriaceae). Further surveys took place in 2006
and 2007, by which time only 10% of the site was unmined. These surveys
confirmed the presence of 42 of the 71 taxa previously recorded, as well as
11 species reported for the first time. It is clear that recent mining activities
have destroyed most of the metallophyte vegetation at this important mine site
(
Fig. 2.4a
). Of the 29 species that have disappeared, three are of major concern;
they were known from only two other sites (
ยด
tolie and Sokoroshe mines)
where they are endangered. However, recently a small area of the site has been
preserved and protected from mining (
Fig. 2.4b
). Unfortunately, this area does
not support the new species. A similar study was made at Tilwezembe, near the
Lupula river where Malaisse and co-workers have been allowed to carry out
botanical surveys in two different seasons. A total diversity of 73 higher plants
has been recorded there. As at Luiswishi, mining activities have progressed
rapidly and only a very reduced rocky area is conserved.
Our knowledge of natural revegetation processes at Cu-Co metalliferous
mine workings in Katanga has only received preliminary study (Leteinturier
et al.
1999
). A set of nine ecological conditions has been suggested, based
upon both the heavy-metal content of soil and its state of hydration. Taxa
have been identified for each condition recognised, with one indicator species
suggested. Research on the cultivation of these taxa is urgently needed in order
to recommend appropriate revegetation strategies to sustain the metallophyte
flora. One very positive initiative commenced in 2004 through a PhD pro-
gramme at Lubumbashi University established in cooperation with Belgian
universities (Brussels and Gembloux). It is designed to produce Congolese
specialists in Katangan phytogeochemistry able to take over conservation pro-
grammes in the mining companies.
Status of metallophytes in Latin America
Knowledge of tropical and sub-tropical metallophyte distribution and ecology
lies far behind that for temperate taxa, especially those in Europe. Few metal-
tolerant and metal hyperaccumulator plants have been reported in Latin
America in comparison to other areas of the world, such as North America,
Oceania, Asia, Europe and Africa (Brooks
1998
). A total of approximately 172
plant species have been described in the literature for the Region as either
metal-tolerant (30 species) or hyperaccumulators (142 species; Ginocchio &
Baker
2004
), a very low number when compared to the high plant diversity
described for the Region (Cincotta et al.
2000
). Most of these plants are nickel-
tolerant and hyperaccumulator plants (89%) as most studies pertain to
serpentine areas in Brazil, Cuba, Dominican Republic and Venezuela, followed
