Dinâmica temporal do estrato herbáceo-arbustivo de uma área de campo limpo úmido em alto paraíso de goiás, Brasil

Abstract

This study evaluated the floristic and structural dynamics of a community of herbaceous-shrub species in an area of moist grassland in Alto Paraíso de Goiás. The first inventory was undertaken in 2000 (T0) and the second in 2007 (T1). Shannon's diversity between the periods was compared by Hutchesonśs t-test, and the fl oristic similarity by the Chao-Sørensen similarity index. Floristic composition and cover, between periods and lines, were evaluated by detrended correspondence analysis (DCA). We sampled 98 species, 88 at T0 and 67 at T1; 31 were unique to T0 and 10 to T1. Floristic diversity in the community was high in both periods, but different between them (t = 7.12, p <0.001), due to variation in species number and coverage. Similarity between the two surveys was high (Chao-Sørensen CI = ± 0.841 ± 0.074). The DCA ordination indicated relationships between the floristic composition and cover with a gradient of moisture and organic matter in the soil identified in T0. There were changes in the lines in the seasonal zones, which became more similar in those constantly saturated with water. During an interval of seven years the moist grassland showed changes in floristic composition and mainly in structure due to increased cover of the clumped tussock perennial species, which were favored by higher soil moisture due to high rainfall in the region.