An uncertain soil transfer. The surprises of ecological restoration and biodiversity offsetting

The rise of biodiversity offsetting policies presupposes that the science of ecological restoration can compensate for the destruction of one natural area by restoring another. However, during ecological restoration operations, ecologists are often surprised by their unexpected results. Drawing on the study of projects carried out in the plaine de Crau, the last remaining steppe in Western Europe, this article analyses the conditions of emergence and the consequences of surprise in restoring the soil. It describes the role played by surprise in various practices (soil transfer, topsoil removal, compaction) to underline its importance in the articulation of ecological science with nature conservation policies. The surprises show uncertainty about the knowledge useful for nature conservation which is not compatible with the need for control and predictability of these policies.