Soil seed bank in a contiguous area of degraded pasture, eucalypt plantation and natural forest, in Paula Cândido MG / Banco de sementes em áreas contíguas de pastagem degradada, plantio de eucalipto e floresta natural, em Paula Cândido - MG

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The present study was developed in the domain of the Atlantic Forest, Minas Gerais State, Brazil, with the objective to evaluate the soil seed bank under degraded pasture, a nine year old Eucalyptus grandis plantation and a semideciduous seasonal forest fragment. In the first part of this study, the soil seed bank was analysed in two sequences of vegetation cover, both made up of natural forest at the upper slope and top positions and, eucalypt plantation at the intermediate position. In one of the sequence, there was degraded pasture at the lower position and, on the other, there was eucalypt, both reaching the water course. The second study included the analysis of the soil seed bank of a sequence having natural forest at the upper slope and top positions and pasture at the intermediate and lower positions, in three different aspects (south, east and west). The soil samples were taken in three transects at the lower, intermediate and upper positions of each vegetation cover. The samples were placed in individual aluminum trays in greenhouses under 11.5 % and 60 % shading. The herbaceous-liana, shrub and arboreal germinated seeds were registered and identified monthly, over a nine month period, excluding grasses that were only quantified. In the first part of the study, 4.518 germinated seeds were distributed into 2.014 grasses, 1.819 herbaceous-liana, 530 shrubs and 155 arboreal individuals. It was found 22 families, 47 genus and 67 species for the herbaceous-liana, shrub and arboreal individuals, respectively. Most seeds (57.9 %) germinated under 60 % shading. The most representative families were Lamiaceae, Rubiaceae and Melastomataceae. The eucalypt plantation presented the highest density of germinated seeds and the natural forest the highest richness. The highest floristic similarity (Ss=0,72) was verified between natural forest and eucalypt plantation. The similarity between eucalypt plantation and pasture was 0,57 and between natural forest and pasture was the lowest (Ss=0,37). Hyptis atrorubens (Lamiaceae) presented the highest herbaceous-liana average soil seed bank importance value (SIV) for the three vegetation cover types; Leandra purpurascens (Melastomataceae) presented the highest SIV for the shrub species and, Cecropia hololeuca (Cecropiaceae), for the arboreal individuals. In the second part of the study, 4.782 germinated seeds were distributed into 2.204 grasses, 1.871 herbaceous-liana, 509 shrubs and 198 arboreal individuals. It was found 26 families, 57 genus and 80 species for the herbaceous-liana, shrub and arboreal individuals, respectively. Most seeds (54.9 %) germinated under 60 % shading. The number of germinated seeds was the greatest at the lower slope position and at the southern aspect. The most representative families for the shrub-arboreal individuals of this study were Melastomataceae, Cecropiaceae and Asteraceae and, for the herbaceous individuals were Lamiaceae and Rubiaceae. Oxalis corniculata (Oxalidaceae) presented the highest herbaceous-liana average SIV for the three vegetation cover types; Leandra purpurascens (Melastomataceae) presented the highest SIV for the shrub and, Cecropia glaziovi (Cecropiaceae), for the arboreal individuals. These results indicate that the vegetation cover, shading, relief position and aspect influenced the soil seed bank floristic composition. It was observed that eucalypt plantation presents a higher soil seed bank floristic similarity with natural forest due to the presence of a greater number of shrub and arboreal individuals.

ASSUNTO(S)

natural resources revegetação forest ecology revegetation recursos naturais conservation bancos de sementes ecologia florestal seed banks silvicultura conservação

ACESSO AO ARTIGO

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