Florística e estrutura da comunidade arbórea de trechos de Floresta Amazônica, Alto Rio Xingu, Mato Grosso, Brasil

• Autor(a) principal: Kunz, Sustanis Horn
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3219
• topic: Floresta Amazônica; Floresta estacional perenifolia; Alto Xingu; Amazonian forest; Evergreen seasonal forest; Upper Xingu; Brazil; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::CONSERVACAO DA NATUREZA

The Seasonal Evergreen Forest is suffering strong environmental impacts caused by agriculture, cattle raising and wood extraction. The worry about the fast decrease in plant coverage of this phytophysiognomy is justified by the scarce knowledge on its floristic and ecological patterns, which is relevant to help in plant coverage conservation and restoration programs. So the aim of the present study was to analyze the floristic composition and the phytosociological structure of the arboreal component of the Hidrographic Basin of Pacas River, as well as the floristic similarity of this phytophysiognomy with other forests of the Amazon domain and Cerrado. Five sampling locations along the basin of the Pacas River were selected, situated at the following farms: São Sebastião, Trairão, Amoreiras and Dois Americanos. At the latter farm, two locations were sampled due to the high disturbance degree in one of them. For the sampling of vegetation, 200 quadrant-points were distributed in each location and 100 points in the location with sign of anthropic disturbance, including all arboreal individuals with diameter at 1.30m above ground (DHB) ≥ 10cm. The floristic similarity was estimated by means of the Jaccard s index and cluster analysis between forest areas of the states of Mato Grosso, Rondônia, Amazonas, Pará, Maranhão and the Federal District. The mean value of the total density sampled in these areas was 740 ind./ha, excepting the area with sign of disturbance in Dois Americanos farm (909 ind./ha). Ninety-four species, belonging to 58 genera and 35 families, were reported. The family Fabaceae had the higher species richness, with 13 species, followed by Melastomataceae (8), Burseraceae and Lauraceae (7). The species with the highest Importance Value were: Ocotea leucoxylon (Sw.) Laness., which was in the first position in all the locations; Xylopia amazonica R.E. Fr. and Myrcia multiflora (Lam.) DC., which were found in four locations, although they were not represented the same way in all stretches. The majority of individuals were concentrated in the lowest diametric classes (10 to 20 cm). The height followed this same pattern in all the locations, the majority of individuals being 6.7 to 16.5m tall. The highest diversity value was encountered in the preserved stretch of Dois Americanos farm (H =3,56), and the lowest was in the stretch of Trairão farm (H =3,17), but both were low considering that they belong to the Amazon Forest. In spite of that, the Pielou equitability was around 0.85, with low abundance concentrations of dominant species. The vegetation of the Pacas River Basin had more similarity to areas of Evergreen Seasonal Forest of Gaúcha do Norte (MT) and to Monodominants Seasonal Forests of Nova Xavantina and Água Boa (MT), suggesting that the flora of the studied phytophysiognomy is distinct from the ones of the surrounding phytophysiognomies. At last, the richness and floristic composition observed are similar along the Pacas River Basin, despite the structural differences between the stretches, especially when considering that several species with high economic value are becoming regionally extinct. In this sense, the necessity of preserving the native forest areas at this hydrographic basin is evident, as well as putting into effect the Environmental Licensing System for Rural Properties.