HARDIN, E. D., K. P. LEWIS AND W. A. WISTENDAHL (Department of Botany, Ohio University, Athens, OH 45701). Gradient analysis of floodplain forests along three rivers in unglaciated Ohio. Bull. Torrey Bot. Club 116: 258-264. 1989.-Direct and indirect gradient analysis related stand tree composition and species richness to maximum detected stand age and successional patterns in relatively homogeneous first bottom floodplain forests along three tributaries of the Ohio River in unglaciated southeastern Ohio. Two-way indicator species analysis and the first axis of detrended correspondence analysis ordination recovered a successional sequence from pioneer stands to older stands that had more species and exhibited a wider range in species richness than younger stands. The second ordination axis reflected a gradient from stands disturbed by timbering and dominated by Acer negundo, to stands with little human disturbance. Acer saccharinum had the highest importance percentage in 25 and was present in 28 of the 30 stands sampled. Tree species colonizing newly deposited alluvium, Salix nigra, Populus deltoides, A. saccharinum, and A. negundo, were present in nearly all of the stands and remain as major components of floodplain forests in southeastern Ohio for at least 100 years in the absence of human disturbance. Stands from the three rivers are compositionally similar and do not ordinate into clearly distinguishable groups by geographical location or river system.