The early successional vegetation stage is crucial for ecosystem development. A good understanding of this stage is especially important in restoration projects. Fluvial systems, heavily human-modified are now subject to increasing restoration efforts such as dam removal, are notably concerned. This study aims to describe the fine-scale spatial and temporal patterns of the initial phase of colonization in a dam removal context using a functional approach. The study was conducted on the Sélune River (Normandy, France), where two dams, 32 and 16 m high, respectively, are in the process of being removed. We recorded vegetation cover and composition changes during the 2015 growing season on dewatered alluvial deposits at two scales and three dates (March, May and July at site scale, March, June and September at impoundment scale). Grime Strategies and functional traits related to sediment stabilization and colonization capacity were recorded for each species according to databases. Physical drivers were estimated using spatial proxies: the distance to and the relative elevation from the channel, the longitudinal distance of the sampling station to upstream. Results showed at the two scales a rapid terrestrialization of the formerly submerged area. The colonization patterns of plant communities during the growing season exhibit an increase in species richness, a shift from ruderal to competitor species and a sediment stabilization potential notably by herbaceous species. Interestingly, we observed meaningful cover of species with hemirosettes all over the vegetation season. Moreover, pollination was mostly operated by abiotic factors in early season, and by biotic factors in late season. Woody species (Salix atrocinerea Brot and Alnus glutinosa (L.) Gaertn) regeneration was registered in the late growing season. Vegetation patterns were more influenced by abiotic factors in the early growing season than in the late growing season. These results highlight the passive restoration potential of vegetation colonization.