Gallery forests in the Cerrado biome possess physiognomic and floristic peculiarities that allow its division in two subtypes: "non-swamp" located in well drained soils; and "swamp" the less studied subtype, located in badly drained soils. The present study aimed to characterize the structure and the flora of two swamped portions in the gallery forests of the Acampamento stream (15°35'S; 48°10'W) and the Riacho Fundo stream (15°55'S and 48°02'W), both in Distrito Federal (DF). In each forest it was allocated a grid of 160×50 m (0.8 ha), composed by 40 plots of 10×20 m (200 m²). All the individuals with DBH > 3.0 cm were surveyed, including the standing dead plants. It was sampled 6,078 individuals, being 3,030 in the swamped portion of Acampamento stream (33 families, 49 genera and 60 species) and 3,048 in the Riacho Fund portion (30 families, 41 genera, 53 species). The basal area (dominance) and the diversity (H') for the studied portions were 47.96 m²/ha and 2.99 nats/ind. (Acampamento) and 41.28 m²/ha and 2.84 nats/ind. (Riacho Fundo), respectively. If compared to others gallery forests previously studied in Distrito Federal, such diversity values are considered low, although they are similar to that indicated for the "Swamp Forests" ("Matas de Brejo") of southeastern Brazil. The similarity indexes of Sørensen (58.0%) and Morisita (70.6%) point to high qualitative and quantitative similarity among portions. However the classification accomplished by TWINSPAN generated two distinct groups, each one linked to one of the portions studied (Acampamento and Riacho Fundo). These results reinforce previous indications that distinct gallery forests in Distrito Federal, or even similar portions on that, show different floristic patches. This variation are related to the hydrographic basin in which the gallery forest is inserted, and the soil drainage.
phytosociology; diversity; gallery forest; Riacho Fundo; Acampamento; Distrito Federal
