DETERMINANT INFLUENCE OF GRAZING IN CONSERVATORY MANAGEMENT IN BRACKISH GRASSLAND SYSTEMS IN MARAIS-POITEVIN (FRANCE)

Despite the recent trends towards intensification in the ''Marais Poit evin'', some wet grasslands are subsisting, and among them, the commun al wet grasslands are particularly representative Convergent observati ons show that vegetal diversity and spatial patterns based on the main tenance of salty zones with subhalophyte species on the border of floo ding depressions are closely linked to the persistence of the grazing through history. Ti-is way of management, joined with the topography r esulting direct from the past salt marshes, induces hydrous and pedolo gic contrasts which generate this agro-ecosystem diversity. This syste m presents a great interest for the studies of grazing impacts. Salini ty variations appear closely linked with the functional modalities oi this system.