Our goal in this paper is to illustrate the importance and utility of references and indica tors in restoration ecology, and in particular those linked to plant biodiversity. References and measurable indicators are essential for determining the orientation of a project, and for the Iong-term evaluation of a restoration project or any other type of environmental operation. The experimental work carried out at Cazarils (southern Languedoc region, southern France), as part of the Ministry of the Environment programme "Recréer la nature", provides the main framework for our remarks, but additional perspective is derived from studies in the artificial Chestnut forests in the nearby Cévennes mountains, and in the semi-natural Pine forests of the Var administrative region, further east, in south-eastern France.In ail three situations, the main driving force to be considered is agricultural and rural abandon ment leading to anarchie, and more or Jess rapid, transformation of formerly cultural Iandscapes into semi-natural ones. This common context allows the evocation of historical changes and the evolution of Iandscapes, and a grea ter appreciation of the difficulties encoun tered when trying to defi ne a viable and pertinent "ecosystem of reference". In the Mediterra nean region, landscapes -both cultural and semi-natural -have evolved rapidly, in recent decades, under the pressure of complex regional and global socio-economic drivers, and envi ronmental management must, therefore, be approached with a weil elaborated and realistic, nested hierarchical approach.This paper also offers the opportunity to briefly discuss the relationships between resto ration, rehabilitation, rejuvenation and ecological engineering, as weil as a vision of environ mental management wherein different interventions of ali sorts, and the conservation of "nat ural capital" would ali be coherent and coordinated at ecosystem, landscape and regional levels.
R É SUM ÉNotre propos est d'illustrer l'importance et l'utilité des références et des indicateurs, et plus particulièrement ceux liés à la biodiversité végétale, pour l'orientation et le suivi et l'évaluation de projets de restauration écologique, ou toute autre intervention de gestion envi-