Efeito da fragmentação florestal sobre a vegetação arbórea e solo em Brejo de altitude

Abstract

The degradation processes of the Atlantic Forest began with the arrival of Europeans in Brazil, intensifying over the economic cycles from the 16th to the 20th century. Currently, approximately 28% of the remaining vegetation is distributed in mosaics along the coast and in exceptional areas in the northeastern semi-arid region. These humid islands, known as “Brejos de Altitude”, are biodiversity hotspots. In Paraíba, the “Brejo de Areia” is one of these areas that underwent different processes of loss and fragmentation due to favorable conditions for polyculture and livestock. Changes in land use and occupation also cause alterations in the soil, such as the deregulation of ecosystem services, such as nutrient cycling in the soil. In this study, two forest fragments in the condition of “Brejo de Altitude” in the municipality of Areia were used as a study area to analyze the effect of forest fragmentation on vegetation and soil. A line of 200 m was delimited from the forest edge to the interior of each fragment, marking the forest edge (0 m), the midpoint (100 m), and the top (200 m) of the fragments. At these distances, a soil profile was opened and the horizons of each soil profile were described and classified. To the north, south, east, and west, 10 m away from each soil profile, 10 x 10 m (0.01 ha) plots were positioned and the DBH (Diameter at Breast Height) and height of 552 individuals with a circumference at chest height ≥ 15 cm were measured. Granulometry, reactivity, and organic carbon content were measured according to procedures recommended for tropical soils. The analyzed data indicated that the vegetation behaves differently between the fragments. In this condition, only fragment 2 presented a “typical” edge effect, where the tested variables increase 100 m from the forest edge. For the soil, the physicochemical variables point to a homogeneous condition of acidity, aluminum saturation, and low natural fertility. This study considered a large number of variables that contribute with information not yet existing for environments in the condition of “Brejo de Altitude” in the Brazilian Northeast, opening space for future investigations.