PHYTOGEOGRAPHICAL AND PHENOLOGICAL COMPARISON OF THE MEUSE AND THE SAONE VALLEY MEADOWS (FRANCE)

The meadows of the floodplains of the Saone and the Meuse contain simi lar ecosystems subject to regular winter and spring flooding. The Aori stic and faunistic biodiversity decreases with the intensification of agricultural practices. The plant communities show the same zonation a long a topographic gradient and have similar floristic progression. Th us, the climatic, biogeographic, human and soil factors have determine d the floristic particularities of each valley. The floristic affiniti es of the two floodplains permitted the comparison of the phenological development of fourteen plant species. Many gaps in the development o f species have been observed. These could be explained by the climatic differences betwen the two valleys (sub-Mediterranean influences in t he Saone and sub-Atlantic in the Meuse), the existence of different ty pes of soils in each valley (sand part more important in the Saone) an d the occurrence of specific ecotypes in each valley.