Floristic-structural heterogeneity of deciduous tropical forest on topographic gradient of limestone outcrop

Abstract

Tropical deciduous forests on limestone outcroppings have great ecological relevance and are threatened, making studies for their conservation and restoration necessary. The objective of this study was evaluate the variation in composition and structure of the shrub and tree component of a deciduous forest in three areas of a topographic gradient in the Serra da Bodoquena. A total of 102 contiguous 10 x 10 m (100 m2) plots were sampled, with 34 plots per relief strip, and a total area of 1.02 ha. All shrubby-arboreal individuals with PAP ≥ 10 cm were included and heights were estimated. Richness estimators, usual phytosociological parameters, and diversity were calculated. The data of the variables were ordered in NMDS by the Bray-Curtis coefficient. As a result, in the total area we obtained 2,385 individuals belonging to 70 species, 49 genera and 29 botanical families, with a basal area of 25.44 m2/ha. The density was increasing from the top to the lower slope. Diversity and equability were higher at the top. Diameters were concentrated in the first class, up to 13.1 cm, and the average height was 5.25 m, with a predominance of understory. Five species sampled had not yet been recorded for the region. Ordination analysis revealed greater distance of plots and species from the hilltop compared to the two hillside areas. Composition and structure indicated topography as a factor generating floristic-structural variations.