In the Andean mountains of southern Ecuador there are areas occupied by high Andean secondary forests as a consequence of anthropic activities. Here we identify different secondary forest communities located over 2900 m a.s.l, based on its floristic similarity. In each community, floristic composition was described by the total exclusive and shared species. Estimation curves were used to provide richness and diversity metrics. The structure was analyzed according to abundance and basal area. In addition, we evaluated the role of environmental variables in floristic conformation and structure through principal components and the redundancy analysis. Three forest communities were identified. Community, located at high altitude and low temperature, had the highest value of diversity and basal area. Variation in species composition was explained by climatic and geographic variables, density by soil and climatic variables, and basal area by topographic variables. Species richness and basal area did not present an altitudinal distribution pattern similar to those from other Andean tropical forests. Therefore, the floristic variation, species richness and basal area seem to be explained by the chronological age of secondary succession, as evidenced by the indicator species belonging to different ecological groups. We concluded that the floristic composition, richness and structure of vegetation in forest communities of high Andean secondary forests are influenced by climatic, topographic, physiographic and geographic variables related to the age of succession.