Estrutura diamétrica e arranjo espacial das espécies mais abundantes de um fragmento de floresta estacional semidecidual em Botucatu, SP

Abstract

We evaluated the diameter distribution and spatial arrangement of the most abundant species in one of the five forest fragments occurring on Edgardia Experimental Farm (1,200 ha) in Botucatu, Sao Paulo state, southeastern Brazil (between latitudes 22°47'30"S and 22°50"S and longitudes 48°26'15"W and 48°22'30"W). The fragment area is 56 ha large. We sampled 185 contiguous plots of 100 m 2 (1.85 ha), accessing the floristic composition and horizontal structure of the vegetation in the center of the fragment. Among the ten species with the highest importance values, seven presented abundance values which allowed studies on diameter distribution and spatial arrangement. The sum of the importance value indexes (IVI) obtained for the most abundant species (185.98) showed that they presented significant weight in the vegetation structure, indicating its regeneration. After adjusting the diameter distributions of the seven species, six showed an inverted J curve of their distribution pattern, reflecting continuous regeneration of plants of such species. Four of these distributions were distinguished as type I, or balanced distribution. These patterns of diameter distributions indicated attenuation of anthropogenic disturbances. There was a direct relationship between spatial arrangement and dispersal syndrome for Trichilia clausseni and Metrodorea nigra and, depending on the scales analyzed, for T.catigua and T.casaretti.