Estrutura e padrão espacial em vegetação de caatinga

Abstract

Northeast’s vegetation, in especial, vegetation about state of Pernambuco, although it had been the subject of several studies from botany and phytogeography, reveals a marked lack of research results in field forestry, especially in relation to caatinga’s sustainable forest management. So, this study wants to be subsidies for a forest management through the spatial pattern study of a caatinga area, it located in Floresta – PE. The study was conducted in two areas, a preserved area with approximately 10 ha (area 1), and another one an abandoned area about 20 years with a disturbance history and approximately 20 ha (area 2). In each one it was mounted 20 and 30 plots (20 x 20 m), respectively, in a systematically way, 80 m apart from each other, where all trees with circumference at breast height (CBH) with 6 cm or less were identified and the height measured. In the area 1 and 2 it were sampled respectily 18 and 20 tree species, distributed in 15 an 17 genera and 6 and 7 botanical families, obtaining a index of Shanonnon-Weaner (H’) of 2,11 nats/ind and 1,67 nats/ind and 4,53 m2/ha and 2,28 m2/ha of basal area estimad. In both of areas the highlights families were Fabaceae and Euphorbiaceae, where in area 1, Fabaceae resulted 48,93% of individuals; and Euphorbiaceae resulted 41,28%, in the area 2, Fabaceae with 76,09% and Euphorbiaceae 16,11%. In order to examine the species aggregation level, were arranged indexes dispersion Morisita ( , Payandeh (Pi), Fracker e Brischle (Ki) McGuinnes (IGA) and highlighted in the area 1 the species Poincianella bracteosa, Croton rhamnifolius, Manihot glaziovii e Mimosa ophtalmocentra with 55 % of the total importance value and and in the area 2 the species Poincianella bracteosa, Mimosa ophtalmocentra, Jatropha molissima e Cnidoscolus quercifolius with 72,41 % of the total importance value. For a detailed analysis about the species in the study area, it was made distribution maps of these, so to have a better understanding of their distributions. About spatial patterns in the area 1 and 2, the majority of species had aggregated distributions, except few species in the area 1 such as Myracrodum urundeuva for the McGuinnes (IGA) index, Commiphora leptophloeos for the McGuinnes (IGA) index and Manihot glaziovii for the Fracker e Brischle (Ki) index that obtained tendency to grouping and in the area 2, where Poincianella bracteosa resulted uniform distribution for McGuinnes (IGA) index and random for Fracker and Brischle (Ki) index and Manihot glaziovii with tendence to grouping for the McGuinnes (IGA) index.