Background. Cycles of flower and fruit production determine the Spatio-temporal availability of seeds and the patterns of seedling establishment in forests, making them crucial determinants of forest regeneration. The intensity and activity of phenological phases depend on climatic events, such as solar radiation, precipitation patterns, and biotic factors such as plant-animal interaction. Most phenological studies on tropical ecosystems are focused on rainy or dry forests. However, these patterns have hardly been studied in tropical mountain forests, like Andean Tropical Mountain Forests (ATMF), which are considered a biodiversity "hotspot" due to the high levels of endemism with a high level of human activity intervention. However, despite being one of the most threatened ecosystems in the tropics, our understanding of ATMF's ecology is still poor.

Objective. We studied the phenology of woody plants with flowering and fruiting intensity changes and activity along a successional gradient.

Methods. We obtained data on fruit and flower production for 68 species during two years (2019-2022). Species were selected from 20 permanent plots located along a successional gradient of ATMFs in the eastern cordillera of Colombia. We monitored 485 individuals and quantified their flowering, fruiting activity, and intensity using visual determination; we attributed a score from 0 to 4 for each plant to estimate each phenological event's intensity. The obtained data was assessed using time-series analyses for evaluating intensity and activity indexes; MANOVA to compare phenology along the successional gradient; and mixed-effect models for climatic variables and phenological activity.

Results and Conclusions. We found that ATMF tree communities have two peaks of activity in fruiting and flowering during the year. Both peaks occurred during the dry season; the first was from February to March, and the second was from July to August. In addition, we found that the intensity of the different phases (i.e., the strength of phenological events) was significantly higher in early successional forests than in late successional ones. Interestingly, the phenological activity (i.e., number of species flowering and fruiting) did not change in the successional gradient. The larger production of flowers and fruits could have been due to the difference in light availability between early (more open canopy) and late (closer canopy) forests or changes in functional species composition along the successional gradient. These results give us essential ecological knowledge to help decision-makers manage plants and restore the ATMF ecosystem.