Floristica, estrutura e formas de vida da regeneração de uma savana amazônica, Pará, Brasil.

Abstract

Amazonian savannas are wealth holders with important ecological potential and currently suffer from anthropic pressure causing environmental losses. The objective of the work was to characterize the phytosociology and life forms of natural regeneration in an Amazonian savanna. The study was carried out in a savanna in the locality of Itapuá in the municipality of Vigia de Nazaré, Pará. Data collection was carried out from September 2019 to November 2020 in 677 plots of 1m x 1m randomly distributed. In each plot, all species with height ≤ 1 m were identified and quantified. The botanical identification in loco was carried out by a parabotanic from the Museu Paraense Emilio Goeldi and characterized in family, genus, species and way of life. The horizontal structure was determined by Relative Abundance (Ar%), Relative Frequency (Fr%), Relative Density (Dr%), Importance Value Index (IVI) and Relative Importance (IR%) with the help of the Mata Nativa Software. The analysis of the vertical structure determined the Relative Size Category (CT%) by species using the Excel program. Species diversity was calculated using the Shannon-Wiener diversity index (H ') and Equability (J'). In the floristic composition, 36,190 individuals were registered, distributed in 43 families, 86 genera and 119 species. Fabaceae, Poaceae and Cyperaceae had the largest number of species. The Herb life form was dominant in 55 species, corresponding to 61.88% of the total sampling. Paspalum, Polygala, Myrcia, Chamaecrista and Scleria obtained richness in species. Eight obtained the highest number of individuals. The highest values of relative frequency, density, value index of importance and relative importance were for Axonopus pubivaginatus. Significant values in the Relative Size Category and relative regeneration included Axonopus pubivaginatus, Paspalum carinatum, Galactia jussiaeana, Hyptis crenata, Axonopus purpusii, Tibouchina aspera and Digitaria horizontalis. The Itapuá savannah showed richness in species concentrated in Fabaceae and Poaceae. Paspalum was the holder of the largest number of species together with other genera, giving dominance to the herbaceous life form. Axonopus pubivaginatus and Paspalum carinatum stood out in all phytosociological parameters of natural regeneration. Conservationist actions must be evaluated for other Amazonian savannas in order to express the ecological, economic and social importance.