The study was conducted in Mijitayo river, which is located in Pasto municipality, in the south-west of Colombia. The general objective was to apply a methodology based in the ecosystems protection to define round river width and the more suitable species to its recovery, having as main element the life zones identification that are in the study area. With this purpose, some of the phytosociological characteristics were studied, among which are: height, coverage, density and relative frequency, which are useful to determine the Importance Value Index (IVI), fundamental parameter along with the drainage density and the area of the afferent basin.The following life zones were obtained in the study site: the lower montane dry forest (bs-MB), the humid montane forest (bh-M), the very montane forest (bmh-M) and the sub-Andean Paramo (p-SA) with an estimated round river width of 15, 25, 29 and 23 meters, respectively. Finally, the recommended species for recovery were Verbesina arbórea, followed by Fuchsia dependens and Bocconia Frutescens for bs-MB; Tibouchina mollis and Verbesina arbórea for bh-M; Baccharis latifolia followed by Maytenus prunifolia and Cavendishia bracteata for bmh-M and finally, Phyllanthus Salviifolius followed by Munnozia Sp for p-SA.