IENE 2016

When development projects generate impacts on biodiversity that could not be sufficiently avoided or reduced, offsets must be designed and implemented to effectively and fully compensate for residual losses of biodiversity. International best practice indicates that biodiversity offsets must achieve no net loss of biodiversity, or preferably a net gain. In France, recent guidance on the mitigation hierarchy is also pushing for such an ambitious goal. How to design and implement such offsets remains a considerable technical and organizational challenge. Losses and gains must be assessed and compared to demonstrate that no net loss can be achieved, in-kind, and on the basis of targeted loss-gain metrics for for impacted species, habitats, etc. Offset feasibility must be assessed, to ensure they can be put in place, especially with regards to access to land and long-term management.

To address this challenge, a dedicated methodology was developed and applied to a new, 80 km, high-speed railway line in Southern France, between the cities of Nîmes and Montpellier. Losses and gains were measured in “offset units”, calculated as quality-hectares per species, and then integrated into a common framework to determine the amounts of each multi-species habitat that had to be restored (and how) to achieve no net loss.

The method was approved by permitting authorities and used to obtain required permits under French and EU law protecting certain species of plants and animals. It wasn’t limited to focusing on these species, however, and generated an offsetting strategy, covering 1800 ha, that integrated other biodiversity components, as well as the concerns of a wide range of stakeholders, and particularly the agricultural sector.

The method was successfully applied thanks to early and continuous engagement with stakeholders, and was shown to enable a rigorous, transparent and participatory treatment of biodiversity impacts from development.