Reeves R. D., Baker A. J. M., Becquer Thierry, Echevarria G., Miranda Z. J. G. (2007). The flora and biogeochemistry of the ultramafic soils of Goias state, Brazil. Plant and Soil, 293 (1-2), p. 107-119. ISSN 0032-079X.
Titre du document
The flora and biogeochemistry of the ultramafic soils of Goias state, Brazil
Reeves R. D., Baker A. J. M., Becquer Thierry, Echevarria G., Miranda Z. J. G.
Source
Plant and Soil, 2007,
293 (1-2), p. 107-119 ISSN 0032-079X
Major collections of the ultramafic flora of Goias, central Brazil, were made by Brooks and co-workers in 1988 and 1990. At the time of reports on this material in 1990-1992 much of it had been identified only tentatively and incompletely, but the area was clearly interesting for taxonomic and biogeochemical reasons. Further progress has been made but still only two-thirds of the specimens are identified at the species level. Following a third collection in early 2005, we now have 800 specimens from this area, with chemical analyses of all the plants and of more than 120 representative soil samples. New species have been found, e.g., in Paspalum ( Poaceae) and Pterolepis ( Melastomataceae). There is a need for more taxonomic work in genera such as Cnidoscolus ( Euphorbiaceae), Lippia ( Verbenaceae), Turnera and Piriqueta (Turneraceae), and Vellozia (Velloziaceae). Ni hyperaccumulation (> 1,000 mg/kg in dry plant matter) has now been found in a total of 79 specimens, representing more than 30 different species. Notable Ni hyperaccumulators include Pfaffia sarcophylla (Amaranthaceae), species of Justicia, Lophostachys and Ruellia ( Acanthaceae), Porophyllum ( Asteraceae), several species of Lippia ( Verbenaceae), Turnera and Piriqueta ( Turneraceae), and a possibly new Cnidoscolus ( Euphorbiaceae). Ni hyperaccumulation has not been found in plants of the outcrops of Morro Feio or Crominia-Mairipotaba; it seems to be confined to the extensive layered ultramafics of Barro Alto and the Macedo-Niquelandia areas. The distribution of Ni-values in the Brazilian plant collection is different from that found in the Mediterranean and California, where there is a clear distinction between accumulator and non-accumulator plants: in Brazil the distribution is more continuous, and median Ni concentrations are much greater. An ultramafic hill just north of Niquelandia deserves to be protected because of the presence there of many of the hyperaccumulators and species probably endemic to the Goias ultramafics.
