Natura 2000 sites, public forests and riparian corridors: The connectivity backbone of forest green infrastructure

The connectivity of protected areas, such as the Natura 2000 network, is crucial for maintaining healthy ecosystems and for the delivery of ecosystem services into the wider landscapes in which they are embedded.We here present a novel combination of methods for connectivity analysis across heterogeneous landscapes, integrating graph-based analyses, least-cost path modelling and the Probability of Connectivity metric, and apply these methods to the network of Natura 2000 woodland sites in mainland Spain. We deliver key insights on the connectors between Natura 2000 sites: their location and width (including transboundary ones), their prioritization in conservation and restoration scenarios involving different land uses, and the bottlenecks (weak points due to land use pressures) found along them. Based on these results, we characterize the landscapes traversed by the connectors within and outside the protected sites to inform related land management decisions.We show that forests of public utility play a key role in sustaining Natura 2000 connectivity in Spain. They may qualify as an effective area-based conservation measure significantly contributing to the connectivity element of Aichi Target 11.Riparian forests were part of the identified connectors much more frequently than expected by their area. They stand out as a crucial green infrastructure safeguarding the connectivity of Natura 2000 woodland habitats, particularly when forest species need to traverse landscapes dominated by agricultural and artificial land uses.Natura 2000 sites have good connectivity conditions compared to unprotected lands. First, the identified woodland connectors preferentially traversed Natura 2000 lands. Second, the large majority of bottlenecks occurred outside Natura 2000. Natura 2000 sites cannot, however, be considered free from connectivity limitations; they still contained a significant number of bottlenecks that would need to be addressed in the site-level management plans.The priority connectors for conservation were preferentially found in the well-forested and well-protected landscapes in the main mountain ranges of Spain. On the contrary, the priority connectors for restoration traversed much more frequently landscapes dominated by agriculture. In these landscapes, connectivity improvements largely depend on the restoration of riparian forests and on measures that mitigate the intensification of agriculture by promoting landscape complexity and natural vegetation remnants. The remarkable spatial segregation found between the priority landscapes for connectivity conservation and those of priority for restoration highlights the need for an integrated perspective for land use planning and for the management of the Natura 2000 network in Europe.