This study aims at identifying the formation of clusters and to evaluate the influence of chemical attributes in the soil on the groups and species in a riparian forest fragment in Campos de Cima da Serra, Rio Grande do Sul (RS). Thirteen plots (10 × 20 m) were demarcated to carry out the study. Forest inventory data were employed in a multivariate analysis using the Twinspan method and the correlation between vegetation data and chemical characterization of the soil was carried out by Canonical Correspondence Analysis (CCA). Thirty-one species were sampled (DBH ≥ 30 cm) and two floristic groups were identified. The results indicated a structural difference between the two environments, likely due to the steeper slope and less influence of groundwater. Variables such as sulfur, calcium and organic matter were explanatory of the vegetation grouping known as riparian forest of hillside and aluminum, aluminum saturation and copper of riparian forest with flat topography.