The requirement for an appropriate assessment applies for each SCI within the meaning of Article 4 HD. In addition, appropriate assessments under Article 7 HD are also required for each SPA within the meaning of Article 4(1) and (2) BD. Both types of sites combine to form the Natura 2000 network and are also referred to overall as Natura 2000 sites (Article 3(1) HD). The requirement for an appropriate assessment is not limited to projects and plans that envisage proposed developments and measures within Natura 2000 sites, but also applies when proposed developments and measures will impact on a Natura 2000 site from outside its boundaries (e.g. because of emissions, barrier or other effects).²⁷ Which projects are obliged to undergo an assessment does not depend on the specific size of the radius, but on the habitat types and species that are protected, the kind of project and impact and on the attribution of effects over distance. Indirect and collateral effects of a proposed development are also relevant to the assessment, insofar as they can be attributed.²⁸ Because no evidence for causality is required in the appropriate assessment, the probability of significant adverse effects due to the proposed development is sufficient.²⁹

An appropriate assessment is to be undertaken in SCIs as required by Article 4(5) HD from the point onwards when the site concerned has been included in one of the European Commission biogeographical lists of sites in accordance with Article 4(2) third paragraph HD.³⁰ Protection at the national level under Article 4(4) HD is not required for applicability, such that any deficiencies in protection at the national level do not affect validity. No impact assessments are necessary in the case of sites that have just been reported by Member States or should have been reported (called potential SCIs), rather more, measures to safeguard the site must simply be taken.³¹ However, the voluntary application of Article 6(3) HD is not prohibited and may be recommendable in individual cases.³² A similar approach applies to sites under consultation within the meaning of Article 5 HD.

SPAs are selected and established solely by the Member States according to Article 4(1) and (2) BD. In accordance with Article 7 HD, the provisions in Article 6(2)-(4) HD only replace the demand for protection laid down in Article 4(4) BD as of the date on which the SPA in question is established in a legally binding manner as a special protection area.³³ The minimum requirement for this process is the precise specification of the boundaries of the site and the aims for conservation and protection.³⁴ In spite of the requirement for a formalised impact assessment, placement under protection constitutes an advantage for projects or plans that will have an adverse impact as, in contrast to Article 6(4) HD, Article 4(4) BD makes no exceptions in relation to the protective system.³⁵ However, protection as an SPA has no retrospective effect, as this contravenes both Article 7 HD and the enforcing nature granted by the ECJ³⁶ to Article 4(4) first sentence BD, whereby Member States are not permitted to gain any advantages from violation of their obligations in relation to designations under Article 4(1) and (2) BD.³⁷ Projects or plans that were approved or decided on prior to designation as an SPA can therefore not retrospectively invoke the later designation during court proceedings.

On principle, no subsequent appropriate assessment is to be carried out for projects and plans that had already been authorised prior to the listing of SCIs or prior to the designation of SPAs, even if the proposed development has not yet been realised.³⁸ However, the execution and operation of these proposed developments are subject to the protective effect of the prohibition of changes and disturbance in Article 6(2) HD.³⁹ Pursuant to the ECJ, this is designed to guarantee a similar level of protection to Article 6(3) HD,⁴⁰ which is why in cases where an appropriate assessment constitutes the sole suitable measure for the prevention of deterioration or disturbance caused by the execution of a proposed development, it must also be carried out within the scope of Article 6(2) HD.⁴¹ This is the case, in particular, if a proposed development can only be realised or continue to exist based on the reasons for derogation stated in Article 6(4) HD,⁴² as a full appropriate assessment is a compulsory condition for a derogation decision pursuant to settled ECJ case law.⁴³

A subsequent appropriate assessment is also necessary if national law already requires a renewed authorisation assessment for an existing project or plan because, for example, significant changes are to be made or the earlier approval was issued for a limited period.⁴⁴ This also applies to replacement constructions, e.g. the construction of a new wind power plant or a bridge, if an authorisation procedure is required for this pursuant to national legislation. Even recurrent measures are to be subjected to an appropriate assessment on principle, unless they can be classified as a cohesive project.⁴⁵

Article 6(3) HD refers to plans and projects without the Habitats Directive defining these terms in greater detail. According to Article 6(3) HD, only projects and plans that are directly connected with or necessary to the management of the site require no appropriate assessment. As a derogation provision, the scope for such associated management developments is to be narrowly defined and is only applicable if such developments are intended to promote the relevant conservation objectives in the site within the meaning of Article 6(1) HD.⁴⁶ All other projects and plans are inherently obliged to undergo an assessment, irrespective of whether they are being instigated by a governmental authority, a company or a citizen. Even projects and plans put forward by the legislature are not exempt from the protective system and are also to be assessed.⁴⁷

2.2.1. Projects⁴⁸

The ECJ refers to the term project in Article 1(2) a) of the EIA Directive for its interpretation of the term and takes a broad view on what projects are. The term includes not only building installations, but also all human interventions in nature and the landscape, in accordance with the second amendment to the EIA Directive.⁴⁹ It is therefore not the kind of proposed development that is decisive, but simply the potential effects on Natura 2000 sites, which is why an appropriate assessment is also necessary for activities that are not intrinsically associated with physical change.⁵⁰ Furthermore, an appropriate assessment is not limited to proposed developments for which an obligation for approval or of disclosure is planned by national rules of procedure.⁵¹ The ECJ has taken clear action against⁵² any attempts by Member States⁵³ to extend the scope of the term project and to thereby limit the applicability of the appropriate assessment through a statutory exemption for specific interventions and types of proposed development. An exemption is only permissible in exceptional cases where the criteria for exemption can guarantee that the possibility of a significant adverse impact on the protected areas due to the projects in question is ruled out.⁵⁴

This is why still an assessment may be required for agricultural, forestry and fishery measures that are generally not subject to approval, if they take place in the vicinity of Natura 2000 sites.⁵⁵ Significant adverse impacts may be present, especially in cases of agricultural, forestry or fishery measures that are not commonplace, such as clearing woodland, the use of plant protection agents in forests, creation of an aquaculture, ploughing of a permanent green area, resumption of extensive exploitation that had been given up or its intensification.⁵⁶ At minimum, a specific obligation of disclosure is required in relation to Natura 2000 to ensure that the responsible authorities have the power to assess the compatibility of all relevant projects in cases of proposed developments that do not inherently require approval or disclosure.⁵⁷

2.2.2. Plans

In contrast to the term project, the ECJ has not yet clarified whether recourse can and should be taken to the definitions of terms used in the European directives on environmental impact assessments, as is the case for the term project. Article 2 a) SEA Directive covers plans that are devised or accepted by national, regional or local authorities (including statutory master plans) and must be compiled due to statutory or administrative provisions. Similar requirements are also to be assumed for Article 6(3) HD as only governmental plans with externally binding or official internal legal effects can predetermine an adverse impact on a Natura 2000 site by a project in a legally relevant manner. The ECJ has made clear that plans and projects devised by legislative bodies are also subject to the obligations given in Article 6(3) HD, as was already mentioned at the start.

An appropriate assessment is only to be carried out if there is the likelihood or threat that a plan or project, either alone or in combination with other projects and plans, will have a significant adverse impact on the integrity of the site concerned, as the conduct of an appropriate assessment involves a substantial amount of work and expense and is associated with delays to projects.⁵⁸ No appropriate assessment is required if this can clearly be ruled out, i.e. without reasonable doubt and relevant uncertainties, by a screening process.⁵⁹ The summary appraisal of a potential threat is to be undertaken based on objective circumstances and under consideration of the specific characteristics and environmental conditions of the Natura 2000 site concerned.⁶⁰ However, there is no obligation to carry out an assessment based on purely theoretical concerns.⁶¹ Conversely, potential thresholds related to bagatelles and irrelevance or mitigation measures⁶² are not permitted to already be included in the screening in support of the proposed development.⁶³ The recognition of such thresholds or measures requires precisely determined adverse impacts, that are only to be ascertained and evaluated in the main assessment as, on principle, any exceeding of the thresholds for reaction and load is significant.

In recognition of the precautionary principle⁶⁴ required under Article 191(2) of the Treaty on the Functioning of the European Union (TFEU) and the importance of the Natura 2000 sites as common European heritage,⁶⁵ settled ECJ case law has established basic requirements for the compatibility of a project or plan under Article 6(3) HD.⁶⁶ In the judgement Sweetman and Others the ECJ had brought his requirements to a good scheme.⁶⁷ The main statements are:

40 Authorisation for a plan or project, as referred to in Article 6(3) of the Habitats Directive, may therefore be given only on condition that the competent authorities – once all aspects of the plan or project have been identified which can, by themselves or in combination with other plans or projects, affect the conservation objectives of the site concerned, and in the light of the best scientific knowledge in the field – are certain that the plan or project will not have lasting adverse effects on the integrity of that site. That is so where no reasonable scientific doubt remains as to the absence of such effects (see, to this effect, Case C-404/09 Commission v Spain, paragraph 99, and Solvay and Others, paragraph 67).

41 It is to be noted that, since the authority must refuse to authorise the plan or project being considered where uncertainty remains as to the absence of adverse effects on the integrity of the site, the authorisation criterion laid down in the second sentence of Article 6(3) of the Habitats Directive integrates the precautionary principle and makes it possible to prevent in an effective manner adverse effects on the integrity of protected sites as a result of the plans or projects being considered. A less stringent authorisation criterion than that in question could not ensure as effectively the fulfilment of the objective of site protection intended under that provision (Waddenvereniging and Vogelbeschermingsvereniging, paragraphs 57 and 58).

The required certainty must be based on objective circumstances and on the best relevant scientific knowledge in the field in relation to the exclusion of significant adverse impacts on the integrity of Natura 2000 sites⁶⁸. This means that any remaining reasonable doubt counts against the proposed development (see 3.3.2). In accordance with the ECJ, an appropriate assessment that has been carried out based on these standards shall not be fragmentary and must contain complete, precise and conclusive findings that are suited to the exclusion of any reasonable scientific doubt in relation to the effects of the planned proposed development on the site.⁶⁹ In the event that no evidence to the contrary can be provided, showing that significant adverse impacts on the site can be excluded if the project is realised, the proposed development is prohibited on principle and the responsible national authority may only approve it under the conditions laid down in Article 6(4) HD.⁷⁰ Adherence to all requirements during the examination by the authorities is to be assessed in full by the national courts in the case of a lawsuit.⁷¹ Overall, the investigation will go into substantially greater detail than environmental impact assessments made under the EIA Directive and the SEA Directive. However, project alternatives are officially to be considered in the derogation assessment,⁷² even if in practice the examination of alternative solutions by project or plan proponents may be the first phase of the process.⁷³

Within the scope of its comprehensive case law, the BVerwG⁷⁴ has amended these requirements in relation to some methodological perspectives (see 3.3) and material aspects.

On principle, the facts of the case that pertained at the time of issuing the decision for authorisation for a project or the resolution on a plan are to form the basis for the screening and the appropriate assessment.⁷⁵ However, the potential future effects of the project or plan on the conservation objectives for the affected Natura 2000 site are to be forecast based on these facts of the case. The decision on whether significant adverse impacts are to be expected or can be excluded without remaining reasonable scientific doubts is thus essentially based on a hypothetical assumption. This is associated with uncertainties, as is the case for all forecasts, the magnitudes of which increase, the higher the range of the temporal scope of the forecast, the greater the complexity of the effects of the project or plan, and the lower the available knowledge on the affected habitat types, species and on the effects that are to be expected.

Article 6(3) HD does not specify methods for data collection or analysis for the conduct of the appropriate assessment.⁷⁶ Nevertheless, the certainty demanded by the ECJ with reference to the exclusion of significant adverse impacts requires a high methodological standard of investigation.

3.3.1. Risk analysis, risk forecasting and risk assessment based on the best scientific knowledge in the field

According to the BVerwG, a specialist scientific consultation on the risk analysis, risk forecasting and risk assessment forms the formal core of the appropriate assessment.⁷⁷ The reason for this is that an individual case evaluation that is essentially dependent on specialist conservation findings and assessments is required to judge whether a project might have significant adverse impacts on the integrity of an SCI or SPA.⁷⁸ This must be based on the current state of scientific debate and the best relevant scientific knowledge in the field, including generally recognised empirical propositions and methods of investigation.⁷⁹ The specialist scientific insights that are gained are to be documented, as this is the only way whereby evidence can be provided showing that the accessible scientific knowledge resources were exploited in full and the assessments have complied with the best possible scientific standards.⁸⁰ Not only the European Commission has produced guidance⁸¹ to simplify the process of determining the most important current scientific knowledge in each individual case, but the authorities in Germany have also compiled specialist scientific conventions and produced working aids on specific questions related to the appropriate assessment⁸² that have been recognised by the BVerwG as important tools for reaching decisions in administrative and court proceedings.⁸³ Nevertheless, the standards specified there – e.g. information on non-significant losses of area or irrelevant pollutants – are only guideline values that claim no normative legitimacy and permit derogation in individual cases.⁸⁴ Furthermore, it must be noted that habitat types, species and natural environmental conditions, as well as scientific insights, generally recognised empirical propositions and methods continue to develop over time, which is why specialist conventions and working aids require constant updating.⁸⁵ Failing this, the responsible authorities are under the obligation to examine whether these actually still represent the best state of scientific knowledge in individual cases.

The required investigations in the Natura 2000 site concerned must consist of concrete observations, based on these scientific insights, empirical propositions and methods.⁸⁶ The investigations must be thorough and permit precise and conclusive findings.⁸⁷ The concrete findings are to be documented.⁸⁸ Older data may only be referred to if the natural and spatial features of the Natura 2000 site have remained largely unchanged⁸⁹ or if these are more likely to result in an overestimate of the pressures on the site than in an underestimate, due to regressive trends in the impact of these pressures.⁹⁰ The BVerwG awards to the authorities a subject-specific appraisal prerogative if multiple procedures for determination and assessment are recognised that use different methods and criteria for investigation.⁹¹ Whereas methods that are regarded as obsolete by the scientific field are prohibited, this must not simply be assumed to be the case if a different method that is recognised would yield results that are not in full agreement.⁹²

However, the state of scientific debate and knowledge in relation to the impacts of diverse proposed developments on habitat types and species is often fluid, and generally accepted specialist scientific empirical propositions are not necessarily available.⁹³ This means there is a lack of the necessary certainty if the risk analysis, risk forecasting and risk assessment do not consider the best state of scientific knowledge or if, from an objective perspective, the relevant scientific knowledge in the field are insufficient at the time to exclude, without reasonable doubt, the possibility that significant adverse impacts will not occur.⁹⁴

However, the BVerwG also sees limits in relation to the obligations for investigation:

The precautionary principle under European Community Law demands that existing scientific uncertainties shall be reduced to a minimum, if feasible (…). This requires the exploitation of all scientific means and resources (…), but does not mean that research is to be commissioned within the scope of a Habitats Directive impact assessment to address gaps in knowledge and methodological uncertainties within the scientific field. Rather more, Article 6(3) HD demands the use of the ‘best available scientific means’ (…). In this case, the recognised scientific methodology includes highlighting the gaps in scientific knowledge that cannot be addressed within a suitable timeframe and estimating their relevance to the findings (cf. Guideline on Habitats Directive Impact Assessment, p. 31). This risk assessment can fulfil the function of developing proposals for effective risk management during the course of the Habitats Directive impact assessment, namely, to determine which measures are appropriate and required to prevent the risk from becoming reality (cf. ECJ, adjudication of 11 September 2002 – T-13/99 – Summary of Decisions 2002, II-3305, margin number 163). In this process, insofar as monitoring appears to be necessary, the environmental management systems standard is to be adhered to (…). ⁹⁵

3.3.2. Handling of uncertainties related to estimates and forecasting

Uncertainties in forecasting and estimating the potential effects and their significance count against the project due to the requirement for certitude.⁹⁶ This handling of uncertainties in relation to forecasting is significantly stricter, than the requirements of the high courts in relation to other decisions on forecasting, at least in Germany, which must only be examined to ascertain whether they were processed using flawless methodology, are not based on unrealistic assumptions and justify the outcome of forecasting in a comprehensible manner,⁹⁷ whereby tenable alternative estimates are no reason for an objection.⁹⁸

It is therefore no surprise that the BVerwG mitigates the strict demands of the ECJ in relation to certitude in cases of scientific uncertainties relating to, for example, interactions that cannot be addressed at the time. The BVerwG therefore states that it is permissible to work with forecasting probabilities and estimates which must, however, be identified and justified.⁹⁹ Conclusions by analogy, presumptions of truth and worst case scenarios are essentially also valid tools, so long as the outcomes achieved through these tools err on the “safe side” with reference to the problems under investigation, they document the crucial facts of the case in a pertinent manner and permit a differentiated conservation concept.¹⁰⁰ For the BVerwG and the Netherlands Superior Administrative Court gaps in knowledge are essentially not an obstacle to authorisation that cannot be overcome if the conservation concept includes plans for effective risk management with appropriate monitoring.¹⁰¹ But in a current adjudication the ECJ was very sceptical in respect of taking into account a following risk management with a multi-phase monitoring.¹⁰² So uncertainties that cannot be cleared up result in the inadmissibility of the proposed development so long as no derogating authorisation is possible under Article 6(4) HD.

3.3.3. Steps in the investigation

The following individual steps in the investigation are necessary for the appropriate assessment:

1. The concrete conservation objectives and relevant objects for assessment in the affected site are to be determined and located as closely as possible based on the declaration on the protected site, Standard Data Forms and management plans (see 3.4).

2. The abundance and condition of protected habitat types in the site, including its typical species, and of the protected species, are to be determined with a survey that is based on current and reliable data¹⁰³ (see 3.5).

3. All possible consequences of the project, individually or in combination with other plans or projects, that might have an adverse impact on the conservation objectives for the site concerned are to be determined and identified (see 3.6).

4. Estimates are to be provided on the extent to which these effects could impact on the protected habitat types and species and whether these could be so negative that the conservation objectives might no longer be achieved in full in the site (see 3.7). In this process, mitigation measures may also be considered in a limited fashion.¹⁰⁴

Article 6(3) HD requires the effects of a proposed development on the integrity of a Natura 2000 site to be assessed in relation to their compatibility with the concrete conservation objectives for the site concerned.¹⁰⁵ The conservation objectives defined for each Natura 2000 site therefore constitute both the item for protection and also set the standard for the assessment.¹⁰⁶ The focus of the conservation objectives are the habitat types listed in Annex I HD and the species listed in Annex II HD, as well as bird species listed in Annex I BD and migratory bird species, based on which the site has been selected. A favourable conservation status is to be safeguarded or restored for these habitat types and species (Article 2(2), 3(1) HD and Articles 2, 3(1) Birds Directive). The Member States first specify which habitat types and species this pertains to for the SCIs in the Standard Data Forms and these are then sent to the European Commission.¹⁰⁷ This is followed later on by a binding specification within the scope of the statutory designation of the protected area. These specifications made in the statutory designation of the protected area precede the Standard Data Forms, which are to be updated accordingly.¹⁰⁸ In the absence of a report, the conservation aims for SPAs are first specified in the statutory designation of the protected area. According to the BVerwG, habitat types and species that are not named in the declaration on the protected area or in the standard datasheet shall not be objects of the assessment, even if these are priority habitat types or species.¹⁰⁹ The Court holds that, in the case of SPAs, only an (appropriate) selection of European bird species from Annex I BD, corresponding to the reporting and site designation procedure, shall form the basis for the assessment.¹¹⁰ All habitat types that may develop only in the future or species that may migrate into the area are not considered at all in the appropriate assessment.¹¹¹

Based on Article 1 e) HD, the typical species in an affected habitat type are also relevant to the assessment, independent of whether they are named in the declaration on the protected area or in the standard datasheet.¹¹² However, the BVerwG has decided that not all characteristic species require inclusion in the appropriate assessment:¹¹³

Those characteristic species shall be selected that exhibit a clear high abundance in the habitat type in question or the conservation of their populations must be directly linked to the conservation of the habitat type in question. The species must be relevant to the recognition and evaluation of adverse impacts, i.e. species shall be selected that possess an indicator function for potential effects of the proposed development on the habitat type. ¹¹⁴

The responsible authority is given some discretionary power in the selection of species.¹¹⁵ Species that react particularly sensitively (e.g. acoustic or optical sensitivity to disturbance) to the effects of a project, or have high or very specific requirements of their habitat, are primarily of relevance, which is why the effects on the habitat type caused by the proposed development would not be adequately documented without their inclusion.¹¹⁶ Species that are higher up in the food chain can be used to make inferences on species that are lower down in the food chain and indirect estimates, based on bat and bird species, of the effects on, e.g., characteristic species of beetles, other insects or snails are therefore permissible according to the BVerwG.¹¹⁷ In practice, investigations in Germany are limited to a small number of species on a regular basis.¹¹⁸ The selected characteristic species are to be treated like species in Annex II HD in the further assessment.¹¹⁹

In individual cases, in addition to the conservation objectives, other elements of the site are to be included in the assessment if these are essential to a favourable conservation status due to the ecological structure and relationships (e.g. margins and buffer zones or species that are an indispensable food resource for the protected species).¹²⁰

In order to be in a position to estimate the effects of a proposed development on the conservation objectives, the abundance and condition of the protected habitat types and species must be surveyed and evaluated. This also includes determining previous pressures on the site due to existing anthropogenic exploitation or long-range pollution, as well as natural changes, e.g. in the climate or water balance.¹²¹ The survey and evaluation methods must be based on the best relevant scientific knowledge in the field (see 3.3.1). The evaluation is to be carried out based on reliable and current data.¹²² According to the BVerwG, older data may only be referred to if the natural and spatial features of the Natura 2000 site have remained largely unchanged and current data are being collected in the immediate area of intervention due to the proposed development.¹²³

With regard to the extent of the data collection and the method, the BVerwG approves a conservation-specific discretion for estimation,¹²⁴ which must, however, be limited to the choice of method and the selection of the characteristic species.¹²⁵ The data collection and evaluation must adhere to the statutory criteria, in particular those laid down in Article 1 e) and i) HD and Annex III Stage 1 HD.¹²⁶ For example, threats that are already present – e.g. due to the influx of nutrients or pesticides – do not justify the classification of a habitat type as an area for development that is worthy of lesser protection if, nevertheless, all characteristics that shape the type of habitat are present.¹²⁷ Furthermore, regular investigations on location cannot be dispensed with.¹²⁸ In addition, a mixture of different data collection methods may be necessary¹²⁹ to obtain a realistic picture of the numbers and condition of the protected species and their habitats.¹³⁰ Habitats used for reproduction and resting, as well as for feeding, including habitats only frequented at certain times of the year (e.g. overwintering quarters), and also the main paths and routes between these habitats are to be identified for mobile species of animals and their importance to the species is to be estimated.¹³¹ The investigations must not disturb the affected animals themselves in a disproportionate manner.¹³² They are to be limited to the required scope and are only to be carried out by experts, exerting the greatest possible level of care in relation to the affected specimens (especially their physical integrity) and the remaining animal and plant life.¹³³

Deficiencies in surveys or in the evaluation of abundance and condition basically render the entire appropriate assessment defective.¹³⁴ However, the BVerwG has decided that analogies, presumptions of truth and worst case scenarios can be used to bridge difficulties in the data collection, so long as the outcomes achieved through these tools err on the “safe side” with reference to the problems under investigation (see 3.3.2). The BVerwG views both a faunistic potential analysis of the landscape¹³⁵ and monitoring that has been only been scheduled for the future as inadequate.¹³⁶

All potential effects of a project or plan for which significant adverse impacts on the integrity of a Natura 2000 site cannot be excluded without remaining reasonable scientific doubts beforehand are to be determined within the scope of the appropriate assessment.¹³⁷ Not only an analysis of the relevant factors associated with the proposed development that may have an impact, but also a forecast of the negative effects on the Natura 2000 site concerned are required, as the assessment must be carried out before the project is realised (see 3.1.).¹³⁸ The data collection must also include impacts outside the boundaries of the site and indirect effects, if these can be attributed to the project (see 2.1).¹³⁹ Minor impacts are also to be determined, as a significant adverse effect on the site may result due to the specific situation pertaining in the site, previous pressures on the site, or the cumulative effects of other developments.¹⁴⁰ Comprehensive data must also be collected on effects if they will clearly have a significant adverse impact on a Natura 2000 site,¹⁴¹ as the findings of the appropriate assessment must always be complete, precise and conclusive and the full conduct of the appropriate assessment is prerequisite to a derogating decision under Article 6(4) HD (see 4).

In particular, certain types of negative effects occur regularly in association with proposed developments. The following examples are highlighted:

• Loss of land in the site due to construction works and installations, resulting in the destruction of, or adverse impacts on, types of habitat and habitats and territories occupied by some species,¹⁴²

• Effects of fragmentations in sites or of barriers both within the site as well as in relation to habitats or populations outside the site, especially in the case of roads, railway lines and waterways, but also e.g. in the case of larger scale wind power plants or opencast mining,¹⁴³

• Risk of collisions due to, for example, the operation of roads and railways or wind energy systems,¹⁴⁴

• Changes to the water balance in the landscape through, for example, a reduction in the groundwater level or changes to/diversions of water bodies in favour of, e.g., roads or railways, mines, energy production, drinking water production or agriculture,¹⁴⁵

• Emissions of noise, vibration, light and compounds within or into the site from the outside, such as nitrogen emissions from roads, power plants or agricultural land or chloride emissions from roads due to winter salting,¹⁴⁶

• Human presence.¹⁴⁷

Furthermore, an appropriate assessment that is oriented towards conservation objectives and focuses on effects is only possible if other negative effects are also considered in addition to the impacts caused by the proposed development.¹⁴⁸ In spite of the project-specific approach of the assessment, the appropriate assessment must not only determine the current pressures due to previous land use, developments that have been realised and long-range pollution, but also the potential adverse impact of other expected, but not yet realised projects and plans under Article 6(3) HD.¹⁴⁹

Projects and plans are not permitted to have significant impacts on the integrity of Natura 2000 sites, either individually, or in combination with other plans and projects, which therefore requires an assessment of the compatibility with the conservation objectives that have been defined for the site concerned. The assessment of significant effects raises a lot of detailed questions and will therefore be examined in greater detail in a separate contribution.¹⁵⁰

A significant adverse effect does not need to have taken place, rather more, the possibility that it is “likely to have” a significant impact is sufficient under Article 6(3) HD.¹⁵¹ Any threat of a disadvantageous adverse effect on the conservation objectives is essentially significant and must be rated as having “an adverse effect on the integrity of a site”, whereby the probability that significant adverse impacts may arise from a proposed development is sufficient.¹⁵² Hence, the recognition of thresholds related to bagatelles and irrelevance by the BVerwG is to be viewed as critical in this process as these undermine protection of the sites in the medium to long term.¹⁵³ Due to the basic requirements, a proposed development is permissible if no reasonable doubt remains that significant adverse impacts will be avoided based on the best scientific knowledge in the field (see 3.1).

Significance is a conservation-specific question that must be solved based on the circumstances of each individual case, without social or economic reflections, which must only be considered within the scope of a derogating approval in accordance with Article 6(4) HD. The crucial criterion for the evaluation of significance is the favourable conservation status based on the conservation objectives for protected habitats and species under Article 1 e) and i) HD.¹⁵⁴ Therefore, the type, scope and duration of adverse impacts is decisive to the question of significance. Permanent land loss due to land use change or intensification essentially always constitutes a significant adverse impact on protected habitat types, as a prerequisite to the favourable conservation status for a habitat type is that the area it covers in the site is stable or expanding.¹⁵⁵ In the case of protected species, adverse impacts must never disturb the species-specific population dynamics to such an extent that a species can no longer form a viable component of the natural habitat that it belongs to and continue to do so in the long term.¹⁵⁶ Relevant factors are the habitat areas of the protected species, including their important areas for withdrawal, resting, nesting and feeding,¹⁵⁷ as well as their conservation status and their potential for improvement (cf. Article 1(i) HD). For this reason, even developments outside a Natura 2000 site may constitute adverse impacts that are pertinent to the assessment (see 2.1).