Floristic composition of forest patches in Southern Amazonia

This paper shows the floristic composition of forest patches in a zone of transition vegetation which exists in the central-east region of Mato Grosso state, more specifically in the municipality of Gaúcha do Norte (13° 10'S and 53° 15' W) where it connects the tropical rain-forest and the seasonal forest. The floristic survey was performed in March 1999 and bisemesterly from August 1999 to March 2001 (during excursions of an average of five days duration) on treks through the border and inside the forests and fanerogamous flora were collected in the reproductive phase. Vegetational samples of shrub-woody species which do not flower or fruit during the sample period were also collected from the 3 ha of the phytosociological survey. The floristic survey resulted in 72 families, 168 genera and 268 species. Of the species, 66 % were woody and 18 % were lianas. The herbs and shrubs were practically restricted to the border areas or clearings and formed 13 % of the total. The epiphytic flora was not very expressive (1 %) when compared to the rest of the Amazon forest, due to the extremely dry regional climate. Hemiepiphytas, parasites and palm trees constituted the remaining percentage. Thirty nine of the species sampled in Gaúcha do Norte had not, at that time, been deposited in the herbaria which maintain representative collections of the flora of Mato Grosso, emphasizing the need for collections in the forest areas of this state.

Amazon; Tropical Rain Forest; Floristic Composition

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