Maria Luiza Porto

Tipos de vegetação metalófila em áreas da serra de Carajás e de Minas Gerais, Brasil

Plants from Serra dos Carajas, state of Para, and Cadeia do Espinhaco, state of Minas Gerais, Brazil, were analyzed for Cu, Pb, Ni, Cd, Co, Mn and Fe concentrations. The results indicate that plants from Carajas concentrate Cu, Pb, Ni, Cr and Fe above background values, and those from the state of Minas Gerais concentrate Ni, Mn, Cu, Pb, Cd and also Fe. Based on the results and on the physionomical aspects of the vegetation we can speculate on the existence of differente types of metalophylic vegetation in these areas, which may belong to a single biogeochemical province (Carajas - Espinhaco) which is rich in iron and other heavy metals.

I - Florística e fitossociologia de campo natural sobre banco de carvão e áreas mineradas, Rio Grande do Sul, Brasil

Studies were conducted at Mina Recreio, Butia, RS, on floristic and phytosociological aspects in a natural grassland area laying on a coal bank and in surface coal mining areas which had beem naturally reclaimed. Two main vegetation units denominated differential units a (AXONOPUS - ANDROPOGON) and B (AXONOPUS - PIPTOCHAETIUM), both of them with their respective sub-units of possibly associated species, were detected in the natural grassland area. The gradual spatial variation, detected in the natural grassland area, is mainly characterized by the set of conditions associated with land declivity and water table depth. In both surface coal mining areas II and III the vegetation units were not clearly defined, but were characterized as primary areas. The vegetation unit PIPTOCHAETIUM - AXONOPUS PURPUSII was detected in area II and a vegetation unit PIPTOCHAETIUM - CYNODON in area III. A greater floristic similarity was verified between area II and natural grassland than between area III and natural grassland. The species detected in mining areas present certain degree of pioneerism and tolerance in relation to the set of extreme conditions which they faced, and should, therefore, be the first to be tested on mining area recomposition.

Tolerância ao cobre em ecótipos de Schinus lentiscifolius March (Anacardiaceae) de áreas de mineração no Rio Grande do Sul, Brasil

Seeds from Schinus lentiscifolius March collected in two mining areas in the state of Rio Grande do Sul, Brazil, were submitted to CuSO4 exposure tests to confirm copper tolerance during germination .and plantule development. The results showed that the two distinct clones respond differently to copper, but both presented tolerance mechanisms. Plantules originated from seeds collected in the area with higher soil copper concentration (minas do Seival) presented toxicity symptoms later as compared to those plantules originated from seeds collected in the area with lower CU2 + concentration (mina Sanga Negra).