Abstract
Continued urban development is a major cause of the loss of biodiversity. In this context, the objective of a No Net Loss (NNL) of biodiversity has been adopted in many countries worldwide. Reaching such an objective requires the application of the mitigation hierarchy, an environmental policy that aims to minimise the impact of urban development. It consists of a hierarchy transposed in France by a sequence of avoidance, reduction and, as a last resort, offsetting of residual impacts on biodiversity that have not been avoided or reduced. Currently, a project-by-project approach with little avoidance, much investment in the reduction of impacts and piecemeal efforts to offset biodiversity losses, significantly limits the effectiveness of the application of the mitigation hierarchy. This difficulty is largely due to a lack of both anticipation and more strategic planning of the mitigation hierarchy by decision-makers at the landscape scale. The purpose of this study is to propose a method that "scales up" the implementation of the mitigation hierarchy from the project-level to a landscape-scale approach. Based on an empirical study, we propose an operational framework for implementation of the mitigation hierarchy at this landscape scale on the basis of spatial indices that are used to (1) set priorities for impact avoidance and (2) pre-identify sites as candidates for offset provision. This methodology provides a much-needed tool to anticipate for the avoidance step and integrate offsetting into the planning process in a more Strategic Environmental Assessment type approach. We show how the use of this method is relevant in a territory that is currently undergoing rapid population growth and urbanization (Montpellier Metropolitan Territory in the south of France). Finally, this paper illustrates the importance of conducting such research in close collaboration with practitioners and public decision-makers to facilitate interactions between developers and conservation stakeholders and improve implementation by land-use planners.