Article 6(3) of Directive 92/43 on the conservation of natural habitats and of wild fauna and flora must be interpreted as meaning that a plan or project not directly connected with or necessary to the management of a site of Community importance, which has negative implications for a type of natural habitat present thereon and which provides for the creation of an area of equal or greater size of the same natural habitat type within the same site, has an effect on the integrity of that site. Such measures can be categorised as ‘compensatory measures’ within the meaning of Article 6(4) only if the conditions laid down therein are satisfied.

The application of the precautionary principle in the context of the implementation of Article 6(3) of Directive 92/43 requires the competent national authority to assess the implications of the project for the Natura 2000 site concerned in view of the site’s conservation objectives and taking into account the protective measures forming part of that project aimed at avoiding or reducing any direct adverse effects for the site, in order to ensure that it does not adversely affect the integrity of the site. However, protective measures provided for in a project which are aimed at compensating for the negative effects of the project on a Natura 2000 site cannot be taken into account in the assessment of the implications of the project provided for in Article 6(3).

This is the case of measures which, in a situation where the competent national authority has in fact found that a project is liable to have — potentially permanent — adverse effects on the protected habitat type on the Natura 2000 site concerned, provide for the future creation of an area of equal or greater size of that habitat type in another part of the site which will not be directly affected by the project.

Such measures are not aimed either at avoiding or reducing the significant adverse effects for that habitat type caused by the project; rather, they tend to compensate after the fact for those effects. They do not guarantee that the project will not adversely affect the integrity of the site within the meaning of Article 6(3) of Directive 92/43.

Furthermore, as a rule, any positive effects of a future creation of a new habitat which is aimed at compensating for the loss of area and quality of that same habitat type on a protected site, even where the new area will be bigger and of higher quality, are highly difficult to forecast with any degree of certainty and, in any event, will be visible only several years into the future. Consequently, they cannot be taken into account at the procedural stage provided for in Article 6(3) of Directive 92/43.

Lastly, the effectiveness of the protective measures provided for in Article 6 of Directive 92/43 is intended to avoid a situation where competent national authorities allow so-called ‘mitigating’ measures — which are in reality compensatory measures — in order to circumvent the specific procedures provided for in Article 6(3) and authorise projects which adversely affect the integrity of the site concerned. It is only if, in spite of a negative assessment carried out in accordance with the first sentence of Article 6(3) of Directive 92/43, a plan or project must nevertheless be carried out for imperative reasons of overriding public interest, including those of a social or economic nature, and there are no alternative solutions, that Article 6(4) of Directive 92/43 provides that the Member State is to take all compensatory measures necessary to ensure that the overall coherence of Natura 2000 is protected.

(see paras 28-34, 39, operative part)