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ABSTRACT
Linear transport infrastructures, whatever their types, fragment the territory and cut off the ecological continuities essential to the fulfillment of species life cycle. At a time when the biodiversity erosion is worsening, the wildlife passages construction is an effective solution as long as they are adapted to the issues of the species present on the site, correctly set, sized, built and managed. Suitable for new constructions as well as for the requalification of infrastructures, wildlife passages must be monitored to assess their effectiveness and, if necessary, adjust their layout. These follow-ups have to feedback on experiences and clarify constantly evolving norms (state of art).
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Read the articleAUTHORS
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Virginie BILLON: Assistant to the Environment Group Manager - Cerema Centre Est, L'Isle d'Abeau, France
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Jean-François BRETAUD: Biodiversity project manager – TVB and wildlife referent - Cerema Ouest, Nantes, France
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Eric GUINARD: Project manager, researcher, ecologist/Ecologist (PhD) - Cerema Sud-Ouest, Saint-Médard-en-Jalles, France
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Eric LE MITOUARD: Environmental consultant - Cerema Ouest, Nantes, France
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François NOWICKI: Biodiversity project manager - Cerema Est, Metz, France
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Laurence THUILLIER: Head of Environmental Studies (PhD) - Cerema Centre Est, L'Isle d'Abeau, France
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Olivier PICHARD: Head of biodiversity and development studies - Cerema Hauts-de-France, Lille, France
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Christophe PINEAU: Ecological engineering group leader - Cerema Ouest, Nantes, France
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Virginie BILLON: Assistant to the Environment Group Manager - Cerema Centre Est, L'Isle d'Abeau, France
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Jean-François BRETAUD: Biodiversity project manager - TVB and wildlife referent - Cerema Ouest, Nantes, France
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Eric GUINARD: Project manager, researcher, ecologist/Ecologist (PhD) - Cerema Sud-Ouest, Saint-Médard-en-Jalles, France
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Eric LE MITOUARD: Environmental consultant - Cerema Ouest, Nantes, France
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François NOWICKI: Biodiversity project manager - Cerema Est, Metz, France
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Laurence THUILLIER: Head of Environmental Studies (PhD) - Cerema Centre Est, L'Isle d'Abeau, France
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Olivier PICHARD: Head of biodiversity and development studies - Cerema Hauts-de-France, Lille, France
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Christophe PINEAU: Ecological engineering group leader - Cerema Ouest, Nantes, France
INTRODUCTION
In 2019, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem (IPBES), also known as the "IPCC of biodiversity", estimated the rate of species extinction to be 100 to 1,000 times higher than the natural extinction rate. This accelerated erosion of biodiversity is almost exclusively linked to human activities. The five major causes of this erosion have now been identified: the disappearance and fragmentation of ecosystems, the overexploitation of wild species, the introduction of invasive alien species, pollution and climate change.
The disappearance and fragmentation of ecosystems in France are partly due to the development of linear land transport infrastructures since the 1960s, particularly when the permeability of these infrastructures for wildlife was not guaranteed. Today, even though there are far fewer new infrastructure projects and ever greater consideration is being given to natural environments, the impact of new cuts often reinforces the existing level of fragmentation.
Land-use planning now involves not only maintaining existing ecological continuity when designing new projects, but also restoring terrestrial, aquatic and semi-aquatic ecological functions that have been interrupted in the past. Solutions adapted to each type of fauna, respecting the behavior of the species and the challenges of the territory, can thus be put in place, in particular wildlife crossings. The requirements (in terms of technical solutions and dimensions) will differ for new infrastructure and for infrastructure to be upgraded.
Whatever the case may be, all the techniques presented in this article require detailed studies, in compliance with regulatory procedures, particularly environmental (Natura 2000, water law, protected species...). The involvement of an ecologist in the project management team, even during the construction phase, is essential to ensure the functionality of the project.
The upkeep and/or management of these assets ensures that the development remains in good condition over time, which also guarantees its effectiveness.
Even if knowledge of wildlife behavior is increasing, and despite the experience feedback available to Cerema, the fact remains that the functionality of the facilities installed must be monitored according to a shared protocol tailored to local issues and the question posed (does the wildlife crossing serve as a habitat...? does it link two populations located on either side of the road...?). The results of this monitoring, which may be envisaged over the longer or shorter term, will enable the system to be adapted if necessary, and will contribute to enhancing knowledge and formulating improved recommendations.
The Ultimate Scientific and Technical Reference
KEYWORDS
ecology | Wildlife passage | Linear transport infrastructures | Wildlife mortality | Traffic
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