Estrutura, estratificação e grupos ecológicos de um fragmento de floresta estacional semidecidual (Uberaba, MG)

Abstract

Seasonal semideciduous forests (FES) occur in patches mainly in the region of the Cerrado of central Brazil, had occupied a expressive area throughout Minas Gerais state. These formations generally occur on fertile and humid soil, characterized for the climatic changes that determines the seasonal deciduousness of the dominant tree individuals, in reply the hydric deficiency. Therefore, studies in these forests are necessary to search to understand the structure and to verify the formation of standards and comparing the floristic composition of this with others fragment. The study was carried out in a seasonal semideciduous forest area located between the coordinates 19º40´35 S and 48º02´12 W. The climate of the region is of the Aw type and the annual average of temperature is presented maximum of 30.3°C, and minimum of 17.5°C and average precipitation is 1630 mm. An area of one hectare, subdivided in five transects of 100 meters was demarcated. Each transect was composed for five plots 20 x 20 m each, totalizing 25 plots. In each plot they had been showed to the tree individuals with circumference ate breast height (1.30 m above of the ground) bigger or equal 15 cm (CBH ≥ 15cm). The usual phytossociological parameters had been analyzed. The density and basal area had been calculated, beyond the indices of Shannon and equitability for the community. The forest was segmented in three vertical stratus based of the average height of all the individuals and its standard error. The floristic similarity of these FES with other FESs was calculated, based in richness and abundance of the species. 806 individuals represented for 90 species had been showed. Late secondary species were frequent in the canopy and sub-canopy, being Micrandra elata (Didr.) Müll. Arg. The most important specie in the community followed of Galipea jasminiflora (A.St. - Hil.) Engl, with presented the greater frequency in the understory. The pioneer species had low representation in the sampled area, what it was waited for an area with good condition of conservation. Associated to this state of conservation, the basal area of 45,8m2/ha is also distinguished, what is not common for this type of vegetation formation in the Triangulo Mineiro. The forest presented the J-invert standard for the diameter distribution of the community, but the more dense species showing distribution out of this standard. The analysis of similarity based on the richness of species demonstrated the formation of four groups, and the factor conservation state and geographic proximity seems to be most significant. Already for the abundance, the analysis did not show formation of groups. The soils demonstrated fertility media and characterized for homogeneity for chemical components, what did not allow the formation of gradients of the showed area. The analysis of the covering of the canopy demonstrated a variation in function of the seasonality. In a general way this remnant studied presents a particular structure and characteristics, well defined stratification and the species domain you would second delayed; thus showing the primary succession state of this forest.