A phytosociological and edaphic study was made of three stands of Betula nigra L. and four communities that lacked this species in the floodplains of the Tuckasegee, Oconaluftee, and French Broad Rivers in western North Carolina. After statistical analyses of the soil factors, stand ordination by principle components analysis, and stepwise multiple linear regression analysis of the biotic and abiotic factors, it was found that total clay was positively correlated with the river birch stands. It appears that the river birch not only can exist in soils with high amounts of soil moisture, but may also require soils which can maintain soil moisture near field capacity on a year-round basis.