Restoring wetland biodiversity: Balancing synergies and trade-offs in multifunctional ditches

Drainage ditches comprise extensive connected networks in cultivated farmland and may represent all that remains of aquatic and riparian habitat in some drained landscapes. The potential for the restoration of wetland habitats and species across agricultural landscapes via the ditch network is widely recognised and active management techniques, particularly widening and modifying drainage channels, have been promoted for the benefit of biodiversity. However, ditches in drained arable landscapes must also maintain hydraulic efficiency to enable cultivation to continue and possible effects on the balance of greenhouse gas emissions in and around the ditch, practical aspects of ongoing management and the economic costs of taking land out of production should also be taken into account. In this case study in the Fens of East Anglia, UK, we examine possible outcomes of different scenarios of drainage ditch modification in a drained arable landscape, and attempt to weigh up potential synergies and trade-offs including: • benefits for different elements of wetland biodiversity and possible drawbacks; • hydraulic outcomes with respect to draw-down and water storage; • effects on greenhouse gas emissions from the ditch channel; • stakeholder perception of the opportunities, economics, synergies, practical challenges and possible barriers to uptake. We make the case for an experimental approach to establishing and monitoring the outcomes of ditch modification; landscape-scale wetland restoration strategies, including a widespread and varied ditch modification programme, as a viable adjunct to raising water tables in fields and incentivisation of ditch management for multiple benefits by means of compensatory payments.