Can ecological engineering restore Mediterranean rangeland after intensive cultivation? A large-scale experiment in southern France

•Four ecological engineering techniques were used to restore a Mediterranean steppe and were monitored after 3 years.•Covering species seeding decreased grass cover, too dense on the rehabilitated area.•Topsoil removal decreased vegetation cover and increased species-richness.•Hay transfer increased target species richness but with a few grasses dominating.•Soil transfer showed the best results with plant community close to the reference but still with some differences.•Despite positive results, no techniques fully restored the steppe in the short term. Ecological restoration has been identified as one of the possible ways to replace biodiversity loss. While ecological engineering methods can successfully restore some ecosystem attributes, restoration is generally incomplete, mainly due to lack of target species propagule dispersal, unsuitable abiotic conditions and negative biotic interactions, especially after intensive cultivation. How best to restore reference ecosystems is therefore a vital research objective, not only on a small experimental scale but also on a large scale. This study aimed to determine which ecological engineering techniques are the most suitable for large-scale restoration of a low-productive species-rich ecosystem after intensive cultivation. Experiments were carried out at La Crau in southern France, within a 357ha land rehabilitation project whose aim was to recreate a herbaceous sheep-grazed habitat. We investigated: (i) covering species seeding, (ii) topsoil removal, (iii) hay transfer, and (iv) soil transfer as methods to restore a steppe plant community in this rehabilitated area, using the last remaining French Mediterranean steppe as a reference ecosystem. Species-richness, diversity and composition of vascular plant communities were monitored over three years. The rehabilitation made it possible to recover a large area dominated by grasses but with vegetation different from that of the steppe. Hay transfer was successful in transferring some target species, but the number of target species did not significantly increase by the end of the third year. Covering species seeding seemed to provide a suitable area for target species colonization, but probable competition with grasses needs to be monitored. The greatest similarity in richness, diversity, and composition with the reference ecosystem was obtained with topsoil removal and soil transfer, which made it possible to recover the species-richness and, to some extent, the