Biomass and net annual primary production were calculated for three flood-frequency zones in the streamside forest coenocline. Aboveground biomass estimates were 290.0 t/ha in the lower flood plain, 142.1 t/ha in the occasionally flooded transition zone, and 234.2 t/ha in the upland. Aboveground net primary production estimates were 12.5 t/ha/yr in the flood plain, 8.0 t/ha/yr in the transition zone, and 10.8 t/ha/yr in the upland. Data on the species distribution of biomass are presented. Biomass and primary production differences along the coenocline are considered to be the result of individual species responses to flooding, available water, disease, and timber cutting.