Résumé : Research was carried out on biodiversity in fallow lands surrounding protected areas in Burundi. Data on biological traits (life forms, seed dispersal and leaf size) were collected for the different compart-ments, reflecting relevant spatial and temporal factors. Results show significant vari-ations in some attributes of these biological traits during post-cultivation dynamics. We determined three indexes to charac-terize this variability. Two of these were significantly effective (Successional Index of life form and Successional Index of seed dispersal), while the third (Succes-sional Index of leaf size) was more corre-lated to site features. Regional disparities linked to the climatic factor effect were also brought to light.