The floristic composition and structure of the vegetation in the valley of the River Comemoração was studied.. The structural survey was carried out on ten transects distributed in terra firme forest (3), riparian forest (5) and open swamp forest (2). The Point centered-quarter method was used, with 50 sampling points, distributed 10 m from each other. At each point four plants were sampled, with the minimum limit of 10 cm circumference at breast height (CBH). All the studied communities showed circumference distributions following a negative exponential curve. Species richness and diversity indices were largest in the terra firme forests; the riparian forests showed largest basal areas; and the swamp forests presented the largest number of individuals/ha, although the basal area/ha was low. In the terra firme forests the most important species were:Qualea paraensis, Maquira guianensis, Macrolobium acaciefolium andDialium guianensis. In the riparian forests the most important species were:Maquira guianensis, Macrolobium acaciefolium, Zygia latifolia, Couratari tenuicarpa, Mauritia flexuosa, Protium apiculatum, Parkia panurensis, Oenocarpus bataua andQualea paraensis. In the swamp forests the most important species were:Pseudobombax cf. faroense, Qualea paraensis, Virola surinamensis, Clusia cf. planchoniana, Macrolobium angustifolium andFerdinandusa guianensis. The great majority (92%) of the species were found in only one community, only 30 species were found in two or more communities. The similarity and cluster analysis revealed a great floristic and structural heterogeneity both within and among the three communities types.
Abundance; Floristic composition; Phytosociology; Woody Vegetation; Amazon