Diversidade e distribuição de espécies arbóreas em duas Matas de Galeria na micro-bacia do Riacho Fundo, Distrito Federal

Abstract

Local variation in the floristic composition and structure of gallery forests seems to be related to slope, soil humidity and light. Would the floristic similarity between patches of different forests under similar abiotic conditions be higher than the similarity between patches of the same forests under different conditions? “Riacho Fundo” and “Açudinho” gallery forests were compared in order to answer this questiono Both forests belong to the “Riacho Fundo” hydrographic basin. Sampling was systematic with sampling lines perpendicular to the main stream. A total of 118 plots (10 × 20m each) placed along these lines were assessed. All individuals from 5cm DBH, except lianas, were measured. In “Riacho Fundo” there were 1,831 living individuaIs (l.58ha sampled, 150 spp., H’ = 4.15) and in “Açudinho” there were 1,228 living individuais (O.78ha sampled, 126 spp., H’ = 4.25). Results seem to indicate that the floristic and structural differences between these forests can be explained by the abiotic conditions, peculiar to each one. According to TWINSPAN divisions, certam patches of different forests that occur under similar abiotic conditions are more similar amongst themselves than to patches of the same forest under different conditions. Water availabilily in the soil, adjacent vegetation types and disturbance history seem to be lhe main determinants of the groupings.