A multistep approach to improving connectivity and co-use of spatial ecological networks in cities

Ecological networks are systems of interconnected components that support biodiversity, ecological processes and ecosystem services. Such structures play a crucial role for nature conservation and people well-being in anthropogenic landscapes. Assessing connectivity by using efficient models and metrics is a sine qua non condition to preserve and improve appropriately these ecological networks. This study aims to present a novel methodological approach to assess and model connectivity for species conservation (Bufo calamita; the natterjack toad) and human recreation in the city. The study used a combination least cost and circuit models to identify priority corridors in the City of Liege, Belgium. Green areas, habitats and relevant movement parameters were derived based on existing studies around (i) the occurrence, ecology and biology of the natterjack toad and (ii) human behavioural studies on urban pedestrians. Combining the two models allowed the assessment of connectivity for both species via two different metrics visualised using priority corridors on maps. The connectivity assessments identified lack of connectivity as the potential route to extinction of natterjack toads at one of the source sites. This study provides examples of how combining least cost and circuit models can contribute to the improvement of urban ecological networks and demonstrates the usefulness of such models for nature conservation and urban planning.