The objective was to analyze the composition, structure and floristic diversity of Loma Alta at three altitudes (164, 300, and 466 m asl) following the Gentry method. We registered 283 species, with Fabaceae (26 spp.) being the most specious family; of these, 101 spp. (36%) are endemic and 87 spp. (31%) belong to some conservation status (including Oreanthes ecuadorensis as Critically Endangered). The structure was composed of 6 diametric classes, concentrating 81% of the individuals, and 7 altimetric classes, grouping 62%, both in the first category. Three types of vegetation were determined: a) dry forest with Xylosma benthamii; b) transitional forest with Gustavia serrata, and c) Garua forest with Rhodostemonodaphne kunthiana as the ecologically representative species. The diversity measured from the richness species was higher (37 spp.) for the transitional forest, the average heterogeneity was higher (H’ = 2.40 nats/ind) for the garua forest, and the average dominance was higher (D = 0.25) for the dry forest. The results provide evidence that can be used to strengthen the environmental management of the protected area at the local and regional level, considering that each forest was highlighted by a characteristic, such as richness, heterogeneity and dominance.