出版社：Arbeitsgemeinschaft Forstliche Standorts- und Vegetationskunde (AFSV)
摘要：For the last ten years impacts from nitrogen deposition within appropriate assessments has been a controversial issue discussed by many experts in Germany. More recently results from a R&D project funded by the Federal Highway Research Institute (BASt) have been published to establish a method on the assessment for road projects. Adverse effects are assessed in a staged approach based on the concept of critical loads: if total environmental deposition is lower than critical loads of the most sensitive feature of the site, no likely significant effects have to be expected. Project contributions up to a de-minimis value of 0.3 kg N ha-1 y-1 are considered as being too small to be measurable. Neither could nitrogen deposition of up to this value be detected in the field nor could damages be attributed to projects contributing such small amounts. Project contributions lower than the proposed threshold thus exert only hypothetical risks that do not justify or even demand refusals of project under Article 6.3. Only project contributions above the cut off criterion have to be considered within an appropriate assessment in combination with other projects. With view on the protected site another threshold of 3 % of the critical load is applied that can be exceeded not only by single projects but also in combination. Its application does not depend on background deposition. It depends on the specific sensitivity of the habitat precautionarily described by critical loads. Examination of scientific results on the effects,particularly along roads has shown that a value of 3 % of a particular critical load clearly lies below detectable adverse effects on the conservation status of natura 2000 habitats. Both thresholds are very low and thus in line with the precautionary approach prescribed by the Habitats Directive. The assessment approach encompasses legal as well as scientific confidence. It also adheres to the principle of proportionality and has proven to be functional in practice. As nitrogen inputs up to 0.3 kg N ha-1 y-1 cannot be realistically attributed to a particular project, they should rather be described as diffuse part of the background deposition. High background deposition in turn should be lowered by the most efficient measures to stay in accordance with the requirement under the Habitats Directive to avoid deterioration. Very small project contributions as accepted by the proposed process will not constitute an obstacle for this.
关键词：nitrogen imp acts; eutrophicat ion; appropria te ; assessment under Art. 6 Habitat directive; Annex I-habitats ; approval procedure
