2. Der Einfluß des Stoffhaushaltes auf Biozönosen in gestörten und ungestörten Auensystemen (The influence of nutrient and mineral turnover on life communities in undisturbed and disturbed floodplains)
[Human impacts on alluvial flood plain stretches: effects on soils and soil-vegetation relations]
Bureau, Fabrice; Guenat, Claire; Thomas, Claude; Védy, J.-C.
A part of the flood plain of the Sarine river (Switzerland) has been modified in the present century by embanking (1920) and damming (1973) the river. The effects of these modifications on the soil and vegetation have been studied by comparing one stretch, the regime of which has been substantially changed by protection and deepening of the river bed, with another that has remained unaltered (i.e. alluvially active). In the latter the vegetation is typical of active alluvium with Willow, Alder and Alder-Ash communities on "F1uviosols carbonatés". The soil diversity is essentially one of a temporal evolution. After embanking the river alluvium accumulated in the protected stretch resulting varied depositional layers. The properties of soil result from an inheritance of material. Embanking has now isolated the stretch from alluvial dynamics, caused an incision of the river bed and a deepening of the water table. In response the vegetation has evolved quickly towards Beech forest and lost diversity.