[Populus nigra L. in the Garonne valley: legacy of the past and present constraints].

This study used documents from archives and historical maps to follow the simultaneous change of the riparian woodlands (where Populus nigra is dominant) and the poplar plantations. Results showed that the riparian woodland decreased by 81% over the two last centuries. Each period was characterised by the dominance of only a few number of clones. The risk of introgression due to the massive presence of such a restricted genetic material around P. nigra was discussed. The impact of river management on poplar regeneration was examined as well.