An Operational Landscape Unit approach for identifying key landscape connections in wetland restoration.
Abstract
Nature conservation and restoration traditionally focus on protecting individual sites. In parts of the world where the natural landscape has been severely altered for agricultural or urban use, individual patches are too small and isolated to ensure effective nature protection. Spatial processes, such as metapopulation dynamics, are disrupted and natural linkages in the landscape, such as water flows, are severed by modifications in the landscape and hydrology. We propose the identification of Operational Landscape Units (OLUs), which are defined as combinations of landscape patches with their hydrogeological and biotic connections, as a tool to facilitate wetland restoration in catchments with a high degree of fragmentation and strongly altered hydrology. The combined consideration of biotic (i.e. dispersal, transports of organisms) and hydrological connections (flooding events, groundwater flowpaths) is a new approach. We developed criteria for the delineation of OLUs in regional wetland restoration initiatives. The key elements for delineation are definition of the restoration objectives, identification of spatial landscape mechanisms and information on historic and present land uses and hydrologic management. As a case study, we delineated an OLU by applying these criteria in a restoration initiative for a large agricultural area that used to be a floodplain until the early 1950s in N.E. Twente, The Netherlands. The OLU encompassed not only the floodplain area to be restored but also a relatively remote nature reserve upstream as well as the stream connecting both areas. By restoring the historic water regime, flooding events would become a regular feature in the two areas and organisms including seeds would flow from the nature reserve to the restored floodplain. Synthesis and applications. Discussions of the proposed Operational Landscape Units with stakeholders (water authorities, nature conservation agencies, farmers) resulted in shared insights which will lead to modifications of the original management plan for the area. We believe the OLU approach will make natural resource managers aware of the importance of spatial processes and connectivity in landscapes and, if properly applied, will lead to more natural and more successful restoration projects.