Estrutura fitossociológica de um fragmento de cerrado sensu stricto no sul do Tocantins

Abstract

The Cerrado biome has the richest flora among the world's savannas and presents a high level of endemism. In relation to the state context, the Tocantins is situated in the geographical transition zone between the Cerrado and the Amazon. The development of this work aimed to evaluate the floristic and phytosociological composition, as well as quantify the necromass and lianas in a Cerrado fragment sensu stricto. In an area of 3.6 hectares, by census, arboreal individuals with chest circumference (CAP) greater than or equal to 15 cm were identified, which had their height measured, as well as individuals who presented lianas using as support. In the area, we also measured the necromass arranged on the soil that was in the area and with diameter of at least 2 cm, using the methodology of smalian, cubing. In addition, woody lianas with diameters ≥ 1 cm at 1.30 m were measured. A total of 8,943 individuals belonging to 75 species were sampled, 69 genera and 33 families of which the families Vochysiaceae and Fabaceae predominated. The total density of the area and basal area were, respectively, 2,484 ind.ha-1 and 13,95 m².ha-1. It was verified by the indexes of Shannon (H '= 3.39) and Pielou (J = 0.79), in comparison with other studies, the high species diversity and heterogeneity. A total of 1,547 woody pieces were measured lying on the ground and suspended above the trees with a total density of 430 pieces.ha-1, most of which were composed of twigs. Regarding the lianas, 2,174 individuals (604 ind.ha-1) were sampled, with a mean biomass of 16.81 Mg.ha-1. In the study area the species that stood out in relation to the phytosociological parameters were: Myrcia splendens, Byrsonima stipulacea, Qualea parviflora, Machaerium brasiliense, Qualea multiflora, Magonia pubescens and Astronium fraxinifolium; high species richness and distribution heterogeneity; few species with the same genera; and greater abundance of necromasses and lianas in smaller diameters is related to the structure of the area since most of the woody species is concentrated in small plants.