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The Serra Negra belongs to the Mantiqueira mountain complex, Minas Gerais, Brazil. It has a vegetation mosaic dominated by ombrophilous and seasonal forest and grassland formations. Woody physiognomies occur on patches of quartzite soils. The aim of the present study was to investigate the patterns of structure and diversity of woody vegetation on quartzite soils in Serra Negra. Ten plots (20 × 50 m) were randomly placed in patches of woody vegetation on quartzite soils along the landscape. The diameter and height of all woody plants with a diameter of ≥ 3 cm at 30 cm from the soil were measured. The 1899 individuals sampled represented 30 plant families and 68 species. A strong ecological dominance was found, with about 30% of individuals belonging to a single species, Eremanthus incanus (Asteraceae). The Shannon diversity index (H′) was 2.74 nats/individual and evenness (J) 0.65. The two most abundant and ecologically important species in this vegetation type, Eremanthus incanus and Eremanthus erythropappus, called ‘candeias’, are exploited in the region, mainly for firewood. This exploitation, combined with other factors (e.g. increased tourism), can pose risks to the conservation of the whole flora of the region.

Preparation of tin(II ] (4). Phase-pure tin(II) sulfide has been obtained by pyrolysis of these precursors at 350• C in N 2 . Thermogravimetric analysis, X-ray powder diffraction, scanning electron microscopy, X-ray electron probe microanalysis and 119 Sn Mössbauer spectroscopy revealed that the complexes decompose in a single and sharp step (1 and 2), or in pseudo-single stage (3 and 4), to produce SnS. We have also measured the bandgap energies of the residues using electronic spectroscopy in the solid state and the result relates well to that in the literature for SnS, 1.3 eV. A decomposition mechanism was also proposed for each complex based on electrospray ionization tandem mass spectrometric results. The synthetic method used in this work might be useful for the preparation of pure SnS on a large scale.