Environmental Heterogeneity Influences Successional Trajectories in Colombian Seasonally Dry Tropical Forests

Environmental characteristics have a major effect on the species composition of seasonally dry tropical forest. However, this effect has been little considered when describing secondary succession of this ecosystem. We tested the hypothesis that local environmental heterogeneity influences successional trajectories when high species richness is available. Changes in species composition and structure were described in 126 vegetation plots differing in successional stage and located along a topographical and soil nutrient gradient. Variation in community composition was partitioned between successional stage, environmental characteristics, and spatial structure using redundancy analyses. In addition, relationships between plot distance matrices for these factors were analysed by means of Mantel tests. High species turnover was observed during succession and species composition similarity was higher among late successional forest than among early and intermediate forests. A higher portion of variation in species composition was explained by environmental characteristics compared to successional stage, whereas the spatial structure of the data was weak. Our results suggest that in the region of study, variation in the successional trajectories is occurring owing to environmental heterogeneity, as well as to human disturbance and other unmeasured processes.