International audienceThe impacts of urban growth on biodiversity vary according to the form and the intensity of urbanisation.However, there is a lack of knowledge about the consequences of the type of urban structure (e.g. mono-centric vs polycentric), the shape of urban boundaries, the local density of residential development, on the habitats of wildlife species. In this context, this paper focuses on the relationship between forms ofurbanisation and functional connectivity of ecological habitats. In the urban region of Besanc¸ on (easternFrance), three emblematic protected species were selected to represent forest mammals. From the initialstate describing current land cover, five prospective residential development scenarios were simulated,corresponding to the form currently most commonly found (e.g. compact development, transit-orienteddevelopment, polycentric development). For each scenario, we also simulate the volume of traffic on theroad network to allow for the barrier effect of roads on habitat connectivity. Then, for each developmentscenario, we model the functional connectivity of habitats of the various target species using landscapegraphs. Results show that compact city maintains more functional connectivity for all the species con-sidered whereas urban sprawl leads to much more marked impacts. Moderately compact and regulatedperiurban scenarios have intermediate levels of impact. The transit-oriented development scenario pro-duces specific impact values according to the species. An interesting point is that the decline in functionalconnectivity of forest habitats is more due to increased traffic than residential development proper. Thisoutlines the relevance of integrated models for simulating both land use and transport at a fine scale

International audienceHabitat restoration is one way of reducing landscape fragmentation, which is seen as a threat to biodiversity. It consists in renovating disused or degraded habitat patches or in creating new habitat patches in suitable areas. Currently, most restoration measures draw on the local knowledge of experts for selecting the best locations. For amphibian metapopulations like the European tree frog (Hyla arborea), the search for such locations must include regional-scale connectivity in order to maintain their viability. We set up a systematic and cumulative protocol for adding new habitat patches to a pond network. Graph modelling is used to include regional-scale connectivity as a criterion to be maximized. Successive locations are tested systematically and connectivity is compared before and after the virtual addition of each new pond. The location that increases connectivity most is identified. The results show that the priority areas identified by the model are similar to those suggested by local experts from a wildlife conservation association. The two approaches are complementary because they are applied on two different scales. The patch addition method can identify strategic areas for improving global connectivity by taking into account the regional scale. Experts' knowledge can target the precise location within the identified area for creating new habitats based on local factors of the surrounding context. In addition, our method can be also used to prioritize locations already decided on by landscape managers. Consequently, this protocol appears to be a useful tool for guiding habitat restoration in the field

Le développement des grandes infrastructures de transport contribue à la fragmentation du paysage et impacte directement la connectivité à l’échelle régionale. En conséquence, la recherche de nouvelles méthodes destinées à atténuer l’impact des infrastructures existantes ou en projet est devenue une préoccupation majeure pour la préservation de la biodiversité. Parmi les méthodes existantes, celles fondées sur la théorie des graphes offrent des perspectives intéressantes pour l’aménagement et la gestion paysagère. Le protocole proposé, basé sur la modélisation du réseau écologique d’une espèce, ou d’un groupe d’espèce, fournit un cadre méthodologique d’aide à la décision pour atténuer l’effet barrière des infrastructures linéaires de transport. Les résultats obtenus permettent de guider les aménageurs dans la recherche d’un meilleur compromis entre contraintes écologiques (atteindre un gain maximal de connectivité) et contraintes économiques (limiter le nombre de passages).

No abstract