Improving wetland connectivity through the promotion of wet arable land

Abstract

Modern agricultural practices have rendered habitat scarce and isolated for wetland species throughout the Swiss lowlands. The targeted promotion of practices that embrace wet arable land rather than drain it may be the key to establishing a robust and thriving wetland network. We test the ability of a recently developed national wetness-potential map (WP-map) to predict the spatial distributions of wetland species of open environments (OW-species), and use the map to model dispersal corridors between Switzerland’s protected wetlands. We first defined a set of OW-species by examining the occurrence of wetland species in relation to land cover types across Switzerland. Using Circuitscape, we then validated a cost raster derived from the WP-map by examining the correlation between OW-species presence and areas with a high probability of movement. Finally, we used the cost raster to generate a Swiss-wide map of least-cost corridors. Overall, OW-species were not only more likely to be found within wet zones of the WP-map, but the effect was amplified in well-connected regions. The pattern was strongest amongst fauna, flora, and bryophytes but mostly absent from fungi and lichens. Our resulting corridor map highlights and ranks potential routes between protected wetland sites according to their permeability and centrality, allowing spatially-explicit prioritization of re-wetting initiatives. When combined with its logistical value in identifying suitable areas for the restoration of wet habitat, the WP-map’s ability to explain the dispersal patterns of the very species suitable to these habitats makes it an invaluable tool for land-use planners.