Análise da cobertura vegetal e estimativas de parâmetros dendrométricos de espécies florestais arbóreas em São José de Espinharas - PB, Brasil.

Abstract

Analysis of vegetation cover and estimates of dendrometric parameters of tree species in São José de Espinharas - PB, Brazil. The objective of this study was to analyze the vegetation cover through estimates of dendrometric and quantitative parameters for tree forest species in a caatinga fragment in the municipality of São José de Espinharas, Paraíba. For vegetation analysis, a forest inventory was carried out by means of random sampling using 32 sample units of 400 m2. The data collection of the inventory followed the guidelines of the Measurement Protocol of the Caatinga Forest Management Network, the inclusion level being CAP ≥ 6 cm. The floristic composition, the qualitative variables, the horizontal and diametric structures of the phytocosis were evaluated. The species Poincianella pyramidalis and Aspidosperma pyrifolium were studied individually for determination of shape factors, stacking factors and wood weight. For this, 20 trees per species were counted using the Smalian method. With the logs of the cubed trees, piles were formed, which were measured and weighed. Wood discs were collected for moisture determination and estimates of the basic density and the average woody biomass per species. We found 18 species, 17 genera and 10 botanical families represented by a density of 1378,91 trees.ha-1. The Shannon diversity index was 1.87 nats.ind-1. The shape factors obtained were 0.77 and 0.81 for P. pyramidalis and A. pyrifolium, respectively, while the stacking factors were 2.96 for the first and 3.08 for the second. The families Fabaceae, Apocynaceae and Euphorbiaceae were the most representative, being the species P. pyramidalis, Mimosa tenuiflora and A. pyrifolium the most important. The values of diversity indexes indicated low floristic diversity. A high number of dead, tortuous and / or forked stems below 2.50 m were found. The shape and stacking factors obtained suggest that there is an overestimation in the volume calculation. The wood of P. pyramidalis was heavier than that of A. pyrifolium, with high yield of woody biomass.