Physiognomic-structural characterization of dry- and humid-forest fragments (Atlantic Coastal Forest) in Pernambuco State, NE Brazil

Although both dry- and humid-forests have been intensively studied, their physiognomic and structural differences have not yet been well characterized. The present work seeks to identify the physiognomic and structural differences between fragments of humid- and dry-forests in the state of Pernambuco, Brazil. The humid-forest fragment was located in the municipality of Sao Vicente Ferrer (7 degrees 7' x 35 degrees 28'W) and the dry-forest fragment in the municipality of Alianca (7 degrees 38' x 35 degrees 14'W). Fifty 10 x 20 m plots were delimited in each area and all individual living plants with a diameter at breast height (DBH) >= N5 cm were included. It was observed that the total density (1,390 ind ha(-1)) and total basal area (29.9 m(2) ha(-1)) were greater in the humid-forest than the dry-forest (649 ind ha(-1) and 18.7 m(2) ha(-1)1, respectively). Individual plants in the humid-forest tended to be taller, while those in the dry-forest had generally larger diameters. There were also differences in the most structurally important families as, for example, Clusiaceae, Moraceae, Myristicaceae, and Sapotaceae in the humid-forest and Sterculiaceae, Fabaceae, Bignoniaceae, and Moraceae in the dry-forest. Physiognomic differences were also observed in the different forest layers, as the group of species composing the canopy of the dry-forest are dominated by deciduous species, while many of the species in the understory are evergreen. In the humid-forest, both the understory and canopy are predominantly composed of evergreen species. The examination of the phytosociological parameters of average height and species richness allowed us to identify physiognomic differences between humid and dry forests in Pernambuco State. The present study demonstrated that dry forests are not simply floristic/structural subsets of humid forests, and that there is a great need to establish conservation areas to protect these important but spatially restricted forests within the Atlantic coastal domain.