The lower stratum is formed by the regeneration of arboreous, arbustive, herbaceous, epiphyte, and liana species, forming an ecological niche of vital importance to the establishment and development of the forest. To analyze floristic composition and structure of the lower stratum of the floodplain forest, it was allocated fifty 50 × 4-m plots, divided in 25 2 × 2-m subplots. All species with diameter at breast height (DBH) < 10cm were identified and quantified. Relative diversity, density and frequency, relative category of size, and relative natural regeneration were calculated. It was sampled 22,221 individuals, 67 families, 153 genera and 223 species, and the Shannon index (H') was 3.72 nat/ind and Equability (J') was 0.69. Fabaceae, Malvaceae and Arecaceae stood out for species richness, and Euterpe oleracea and Virola surinamensis for relative density, relative category of size, and relative natural regeneration. The arboreous habit presented the greatest number of species and individuals in the size classes 1 and 2. The adaptation mechanisms and fruit production are related to the diversity of the area, where the species with the most efficient strategies are dominant and more quantitatively representatives in the community.
Regeneration; Richness and size classes; Conservation unity
