Managing water control in AtlanticCoastal Wetland : Grasslands for grazing and amphibian conservation

International audience

إنجليزي. The grasslands of the agricultural fresh water marshes of the French Atlantic coast are devoted to extensive suckler cattle farming, which provides a habitat for and preserves a fauna specific to wetlands. Managing water levels in the ditches of these clay marshes is a key factor in controlling the flooding of the grasslands, given the slight variations in topography and the associated gravitational transfers.Controlling the flood is one of the major levers for biodiversity, whether in terms of plant communities or amphibian populations, while ensuring the grass quality and growth are staggered over the summer season, for the herds.The development of low-cost, open-source GNSS buoys, coupled with a digital terrain model, allows real-time monitoring of water levels in the ditches and flooding in the grasslands. This monitoring, combined with a conceptual model of the expected flooding levels in the grasslands by season, ensures the functionality of the grassland habitats necessary for amphibians, while also guaranteeing sufficient forage production for the herd. This enable a protocol to be established for controlling the sluices that regulate water levels.Thanks to this monitoring, we maintain water levels within a variation range of ±5 cm from a seasonal management guideline. This guideline ensures that 1 hectare of a target parcel remains flooded for 5 months of the year, thus creating a habitat that is favourable to amphibians. We achieve our goal of maintaining a population of 10 Parsley frogs on the farm, while producing grass for cattle, staggered over the summer period.This monitoring is constantly being improved, thanks to technical adjustments to simplify sluice management, field campaigns to validate simulations of water level in the grasslands, and the adaptation of management guidelines based on the acquisition of new knowledge about the links between water management, biodiversity, and grass growth