Biodiversity in the floodplain of Saone: a global approach

Biodiversity of European floodplains is seriously threatened mainly due to (1) modifications of river courses such as channelisation or embankments, a nd (2) changes in traditional agricultural practices (i.e. usually pastures ), into intensive production using drainage and fertilisation. A upstream-d ownstream survey of the Saone floodplain (France) has been done to identify the contribution of habitats to the floodplain biodiversity. Selected taxa were aquatic and terrestrial vegetation, Odonata, Coleoptera, Amphibians, and birds. The taxa were sampled in different habitat types that were: fore sts, grasslands and aquatic habitats. Tributary confluences with the river and cut-off channels contributed greatly to the floodplain diversity accord ing to their invertebrates and aquatic vegetation communities. The abundanc e of rare species (benefitting of a national or regional protection status) was the highest in hygrophilous grasslands. Moreover, we demonstrated that diversity of breeding bird communities was correlated with the size of the se habitats. We demonstrated also that alluvial forests contributed to main tain some particular species as Middle-spotted Woodpecker (Dendrocopus medi us), while new plantations were colonized by openland bird communities sens ible to the edge effect. Grassland fragmentation for agriculture appeared t o be a major cause in biodiversity loss. Any alteration of the floodplain d ynamics must be avoided to preserve the present diversity of riverine wetla nds.