The added value of the Habitats Directive: is biodiversity better protected since the Directive entered into force?

Assessing the status of biodiversity is a big challenge, since biodiversity is not comparable to a chemical substance that (like ozone concentrations in a city) can be easily measured in real time. The defi nition adopted by the Convention on Biological Diversity shows how complex biodiversity is:Biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.1