Caracterização florística e fitossociológica da regeneração natural em dois trechos de uma floresta estacional semidecidual no município de Viçosa, MG

• Autor(a) principal: Silva Junior, Wilson Marcelo da
• Data de Publicação: 2002
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3199
• topic: Floresta estacional semidecidual; Composição florística; Estrutura fitossociológica; Regeneração natural; Fotografia hemisférica; Seasonal semideciduous forest; Floristic composition; Phytosociological structure; Natural regeneration; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::CONSERVACAO DA NATUREZA

The objectives of this study were to study comparatively the floristic composition and the natural regeneration structure of the shrub and trees components in two sites of the Mata do Paraíso Reserve Forest located in the district of Viçosa MG, and to discuss, through the group of information obtained, the soil and vegetation restoring capacity of the Semi deciduous Forest after strong antropic disturbance. Two sites of the forest were chosen considering the successional stage, being the first an abandoned pasture area in true regeneration process for about 30 years, in this study called Young Forest, and the second, a well preserved forest nucleus without antropic intervention in the last 35 years, here called Mature Forest. In each site, ten plots of 4X10 meters were placed, in which all individuals with a height superior or equal to 1,50m and DBH inferior or equal to 5,0cm were sampled. In these plots, interior sub-plots of 2X10m were placed, in which all individuals with height between 0,30m and 1,49m were sampled. All individuals had their diameters at soil level and height measured, and the taxonomic identification taken. In the center of each parcel canopy hemispheric photographs were obtained. For the soil sampling, four samples in each plot were collected composing a compound sample for each forest site, where the chemical and physics analyses were done. On the whole, there were 2456 individuals sampled belonging to 39 families, 83 genera, 121 species and eight morphospecies. The richest families were Rubiaceae (13), Meliaceae, Mimosaceae and Myrtaceae (8), and Fabaceae (7). Seventeen families showed one specie. In the Young Forest Psychotria sessilis, Siparuana guianensis, Trichilia pallida, Anadenanthera macrocarpa, Erythroxylum pelleterianum and Nectandra rigida occupied the first positions in importance value, considering the two sampling levels. In the Mature Forest Euterpe edulis, Coffea arabica, Justicia sp., Picranmia regnelii, Guarea macrophylla, Guapira opposita and Psychotria hastisepala were the most important in both sampling levels. Considering the species classification in successional categories, in the Young Forest there was a predominance of the pioneers and initial secondary in both sampling levels showing that this site has not achieved an advanced succession state, whereas the late species predominance in the Mature Forest shows an advance in succession in this site. The cluster analyses revealed a clear separation of two big groups, each representing one site of the Forest. Besides the floristic differences, both sites also showed soil status fertility and canopy opening differences, with the Young Forest being poorer in soil nutrients, and having a more open canopy than the Mature Forest. So, in the Young Forest the ecological conditions, especially light, must be increasing the regeneration of the species in the initial succession stage, whereas the grater fertility and shading conditions of the Mature Forest are increasing late secondary species. Therefore, it can be concluded that the abandoned pasture period has not been enough for the floristic composition restoring and the succession advance towards a condition near that of the seasonal semideciduous forest of the region. The soil degradation in this section is still reflected in the low nutrient contents, high acidity and compacting in relation to the Mature Forest, which must also be reflecting in the floristic structural and successional differences between the two areas. As a strategy to accelerate the succession process in the Young Forests, the late species planting, even with fertilization, is recommended. The late species with greater importance value in the Mature Forest, and the pioneers in the Young Forest, can be indicated for species planting enriching of scrublands and forest restoration in degraded areas, respectively.