Endozoochory, the dispersal of seeds by animal ingestion, is the most dominant mode of seed dispersal in tropical forests and is a key process shaping current and future forest dynamics. However, it remains largely unknown how endozoochory is associated with environmental conditions at regional and local scales. Here, we investigated the effects of elevation, climate, and microhabitat conditions on the proportion of endozoochorous plant species in the seed rain of the tropical Andes of southern Ecuador. Over 1 year, we measured seed rain in 162 seed traps on nine 1‐ha forest plots located at 1000, 2000, and 3000 m a.s.l. We recorded climatic conditions (mean annual temperature and rainfall) in each plot and microhabitat conditions (leaf area index and soil moisture) adjacent to each seed trap. In total, we recorded 331,838 seeds belonging to 323 morphospecies. Overall, the proportion of endozoochorous species in the seed rain decreased with elevation. The relative biomass of endozoochorous species decreased with increasing rainfall, whereas the relative seed richness of endozoochorous species increased with increasing temperature and leaf area index. These findings suggest an interplay between climate factors and microhabitat conditions in shaping the importance of endozoochorous plant species in the seed rain of tropical montane forests. We conclude that changing climatic and microhabitat conditions are likely to cause changes in the dominant dispersal modes of plant communities which may trigger changes in the current and future dynamics of tropical forests. Abstract in Spanish is available with online material.

Many theories have been proposed to explain the high diversity of plants in the tropics. However, we lack an understanding of the processes that drive plant diversity and community assembly at different spatial scales. Here, we applied beta-diversity partitioning to test how biotic and abiotic factors are associated with seedling beta-diversity in a tropical montane forest in southern Ecuador. We recorded seedling communities on 81 subplots in nine plots located at three elevations along a 2000 m elevational gradient. We measured biotic pressures (i.e. herbivory and fungal pathogen attacks) and environmental conditions (i.e. soil moisture and canopy closure) in all subplots and related them to species turnover and richness differences in seedling communities within and between elevations. We found that species turnover increased with differences in biotic dissimilarity within elevations, while differences in species richness within elevations increased with increasing environmental dissimilarity. Between elevations, species turnover increased with increasing environmental dissimilarity. Our findings show that species turnover and changes in species richness are related differently to abiotic and biotic factors, and that the importance of these factors for shaping seedling diversity is scale-dependent. Our study contributes to better understand the processes driving seedling beta-diversity and the assembly of plant communities in highly diverse tropical montane forests.