An index of naturalness

Summary ncept of naturalness both as a conservation value and as a descriptor of state is discussed. Previously used indexes or criteria for expressing naturalness are summarised, pointing out particular conservation activity fields where a structured index ought to be useful. Strongly focused on its practical application, a qualitative index for expressing naturalness of a given system is developed. The index ranks from a maximum of [10] to a minimum of [0] (artificial systems). Its ecological foundation (system analysis), diagnostic criteria and application procedures (mapping included) are explained. Finally, a set of three examples taken from different working scales is presented: an archipelago (Galapagos), an island (El Hierro) and a map sheet at scale 1:25 000. The latter examples originated in the Canary Islands. The index has been tested on oceanic islands, but it can be applied to any environment.