Characteristics of tree species at a riverside forest were investigated from forest inventory and tree-ring analysis of stem transections in three quadrats (100m^2 each) along Duda River in Macarena National Park, Colombia. As the distance from river channel became longer, the number of living individuals decreased from 108 to 45,while the canopy height (H) increased from 10m to 20m, the diameter at breast height (D) increased from 10cm to 25cm. As the result, the total D^2H increased from 1.39m^3 to 11.62m^3/100m^2. Cecropia membranacea was widespread in all the quadrats. This species has the characteristics of fast thickening growth in the early stage but the cycle between establishment and death is shorter than other species. It was also estimated that the species has a fast extension growth as well from the analysis of vessel parameters. Ficus insipida and Piptadenia flava were believed to be canopy species because they have a large vessel diameter and their growth rate is steady, while Guarea guidonia and Inga bomplandiana were thought to remain in the medium story by mainly having thickening growth.