Relações florísticas e estruturais entre fragmentos de florestas secas e úmidas (Floresta Atlântica), Nordeste do Brasil

Abstract

Although both dry- and humid-forests have been intensively studied, their physiognomic and structural differences have not yet been well characterized. The present work sought to identify the physiognomic and structural differences between fragments of humid- and dryforests in the state of Pernambuco, Brazil, as well as, verify the floristics affinities between the types of northeast Atlantic Forest and to evaluate through the register of occurrence if it exists a group of characteristic species of a dry forest and to infer on the status of conservation of these species for the state of Pernambuco. The humid-forest fragment was located in the municipality of São Vicente Férrer (70 37’S x 35° 28’W) and the dry-forest fragment in the municipailty of Aliança (7° 38’S x 35° 14’W). Fifty 1Ox2Om plots were delimited in each area and all individual live plants with a perimeter at breast height (PBH) greater than or equal to 15 cm were included. Based on a presence/absence matrix of 39 floristics lists of the northeastern Atlantic Forest, it was realized analyses of similarities, PCA and TWINSPAN. It was observed that the total density (1390 ind.h-1) and total basal area (29,9 m2.ha-1) were greater in the humid-forest than the dry-forest (649 ind.h-1 and 18.7 m2.ha-1, respectively). Individual plants in the humidforest tended to be taller, while those in the dry-forest had generally larger diameters. Besides, it exists differences in the families structurally important, as for example, Clusiaceae, Moraceae, Myristicaceae and Sapotaceae are important families in the humid forest while Sterculiaceae, Fabaceae, Bignoniaceae and Moraceae are important in the dry forest. The set of structurally important families and species between the two forests is distinct, consequently these families influence in the physiognomic patterns in each forest. The set of structurally important families and species between the two forests is distinct, consequently, this set influences in the physiognomic standard founded in each forest. The analyses of similarity, TWINSPAN and ordination had been consistent in the indications of the floristics groups. Two areas of dry forest form a differentiated floristic group from analyzed areas of Pernambuco, and consequently, a different floristic group of the humid forests. Among the 14 species that had analyzed yours distribution standard, 10 had been registered exclusively in the dry forest from Pernambuco. This work showed that the floristic composition, structure and physiognomic between the forests studied are distinct.