Building up a diachronic analysis from multi-source data to characterize consequences of dam removal on agricultural landscape - biodiversity interactions.

In the coming three years (2015-2018), two dams will be removed on the Selune River (Baie du Mont Saint Michel, France) in what appear as an unprecedented case of study in Europe for monitoring changes in terms of farming practices, ecological restoration and landscape organization. But to characterize future trajectories, we need to fully understand past evolution of agricultural landscapes in the Selune catchment. Indeed, analysis of landscape structure changes in the past will provide knowledge on the interactions between agriculture areas, riparian areas and slopes.The objective of our study was to characterize the structure and dynamics of agricultural landscapes, from the river to the plateaus, on the Selune catchment. Two lines of work were followed: (1) an historical inventory of landscape occupation for several years (wide range, large scale) and (2) a monitoring of the current landscape changes before, during and after dam removal (low range, small scale). We used a remote sensing analysis in a diachronic approach. This approach draw benefits of a cross analysis between multi-source data. Using this analysis throughout the development period, we will be able to evaluate the contribution of agriculture to the changing dynamics of the landscape and its associated plant biodiversity, as well as the relative weight of landscape evolution in the changes observed in riparian vegetation.