As a characteristic of ecosystems, which enhances their social value, biodiversity thus appears both as a local and a global common. As the conservation of biodiversity provides benefits at different organisation levels, a welldesigned management framework should articulate local
and global public benefits [24]. More generally, Ostrom [25] argues in favour of a polycentric governance of biodiversity based on the ‘‘law of requisite variety’’, which states that any regulative system needs as much variety in the actions as there is in the system to be regulated. However, at each level, there must be a narrow enough congruence between the effective management rights and the awareness of the social values at stake.