Results of floristical and phytosociological investigations on the ponds of the south-eastern part of department of Nord (France).

This botanical monograph of 17 ponds from the south-eastern part of department of Nord (France) begins by an analysis of natural characteristics and some ecological factors allowing to elaborate an ''abiotic'' typology of ponds. Floristical investigations have allowed to list protected and/or threatened species at national and especially regional levels and constitute the basis of a floristical hierarchization of ponds, In a phytosociological study, we have recognized about twenty plant communities, with a new association, the Impatiento - Scirpetum sylvatici. With these communities, we have constituted a landscape typology of the ponds and a new hierarchization, besides significatively correlated with the floristical one. A data analysis has finally allowed to associate plant communities and ecological factors, followed by advices for a reasoned management of the ponds.