Spatial and temporal patterns of denitrification in a riparian forest.
Spatial and temporal patterns of in situ denitrification were investigated along a riparian forset (Ulmus minor, Fraxinys angustifolia, Cardamine pratensis, Alnus glutinosa, Carex remota, and Carex riparia) catena situated along the River Louge in southern France. Highest rates of in situ denitrification (up to 78 mg N m-2 day-1) were measured in the riparian forest soils in late winter and early spring. Lowest rates (3 mg N m-2 day-1) were measured in summer and autumn. Regardless of season, 30 m of riparian buffer strip were enough to remove all the nitrates coming through the groundwater. Rehabilitation of riparian zones with riparian vegetation together with the maintenance of waterlogged conditions induced by riverflow regulation appears to be a good point from which to start the restoration of buffering capacities of river ecosystems against nitrogen loads.