Safeguarding Natura 2000 habitats from nitrogen deposition by tackling ammonia emissions from livestock facilities

Highlights

• We evaluated the Flemish policy to reduce ammonia deposition in Natura 2000 areas.

• The policy is ineffective in lowering deposition below critical loads.

• Emission abatement should extend beyond the livestock sector.

• The cost of abatement differs between livestock subsectors.

• The effectiveness in individual habitats depends on the sensitivity of the habitat.

Abstract

Nitrogen deposition is one of the main environmental threats to the conservation goals in areas protected by the European Habitats Directive, a problem that is quite pronounced in the livestock-rich region of Flanders, Belgium. Livestock farms are often located close to Natura 2000 areas. Therefore, ammonia emissions from livestock housing and manure storage have a high contribution to the deposition in these nearby protected habitats. In order to control this problem, the Flemish government imposes restrictions on livestock farms that pose a substantial threat to protected habitats nearby. In this paper, we evaluate the effectiveness of this spatially differentiated policy. Using an integrated spatially explicit modeling approach, we were able to show that the effectiveness of this policy is rather limited in terms of reducing the proportion of habitats in exceedance of the critical load for nitrogen. In order to obtain a good status for all sensitive habitats, emission abatement efforts should extend beyond the livestock sector. The effectiveness of the policy is dependent on habitat type and the livestock subsectors contributing to emissions nearby. Furthermore, by means of four different habitat classes, the effectiveness of alternative policy options can be easily assessed on the level of individual habitats.

Introduction

The emission of nitrogen oxides (NO_x) and ammonia (NH₃) to the air contributes to eutrophication, due to deposition of these reactive nitrogen compounds on soils, vegetation and surface waters (European Environment Agency, 2018a). The sensitivity of ecosystems to this process of atmospheric nitrogen deposition is reflected through the critical load, the amount of nitrogen an ecosystem can maximally absorb without negative effects (European Environment Agency, 2018a). In 2016, the critical load for eutrophication was exceeded in 73 % of the ecosystem area in the EU28 (EMEP, 2018). Nitrogen deposition is one of the major threats to the Natura 2000 network, the pan-European network of protected sites aimed at conserving or restoring threatened and endangered species and habitats, established by the European Habitats Directive (Schoukens, 2017). Article 6 of the Habitats Directive imposes member states to avoid further deterioration of habitats and additional adverse impacts, which puts a limit to permitting additional nitrogen emissions in the vicinity of Natura 2000 sites (Schoukens, 2018). In the long-term, the EU’s objective is to have non-exceedance of the critical load in all European ecosystem areas (European Environment Agency, 2018a).

Among the economic activities most affected by this legislative requirement is agriculture: it contributes 92 % of the total NH₃ emission in the EU (European Environment Agency, 2018a), while farms often have a relatively high impact on neighboring natural sites because of the fact that most of the emitted NH₃ is deposited close to the emission source (Loubet et al., 2009). The livestock sector has a share of 82 % of the total agricultural NH₃ emission (Leip et al., 2015). Emissions from animal housing and manure storage can be considered as point sources, in contrast to diffuse emissions coming from manure spreading and grazing (Carnell et al., 2017). Due to the high spatial variability of the NH₃ concentration and deposition, and different sensitivities of ecosystems (Vogt et al., 2013), spatially-targeted emission abatement is a favorable policy strategy to alleviate ammonia deposition in Natura 2000 areas (Dragosits et al., 2006; Hicks et al., 2011).

Meeting the EU’s long term objective of not exceeding critical loads of eutrophying substances in all ecosystem areas (European Environment Agency, 2018a) will not only require efforts by livestock farmers in Flanders. Other nitrogen-emitting sectors will also have to contribute to deposition reduction. However, the nitrogen oxide emissions from transport, industry and energy in the EU have declined considerably more than ammonia emissions from agriculture (European Environment Agency, 2018a). In the EU28, the overall emissions of NOx have declined by 58 % between 1990 and 2016, while the emissions of NH3 declined by only 23 % (European Environment Agency, 2018b). Reduced nitrogen is already the dominant contributor to nitrogen deposition in Flanders: of the total nitrogen deposition in Flanders in 2017, 59 % consisted of reduced nitrogen (NHx), 32 % of oxidized nitrogen (NOx) and 8 % of dissolved organic nitrogen (Vlaamse Milieumaatschappij, 2018). 46 % of the nitrogen deposition is attributable to sources outside Flanders (Vlaanderen Departement Omgeving, 2018), indicating that a pan-European effort in reducing the emissions of reactive nitrogen compounds is needed. Furthermore, as Flanders exports three times as much nitrogen deposition than it imports (Vlaanderen Departement Omgeving, 2018), reductions in Flemish emissions will also contribute to ecosystem improvement in neighboring countries. Regarding the share of Flemish emission sources in the nitrogen deposition in Flanders, agriculture (74 %) and transport (17 %) are the main contributing sectors (Vlaanderen Departement Omgeving, 2018). Of the ammonia emissions due to livestock farming in Flanders, 70 % arises from animal housing and manure storage, 22 % from manure application on the land, and 8% from pasturing (Vlaamse Milieumaatschappij, 2019).

In accordance with Article 6 of the Habitats Directive and in order to improve the conservation status of Natura 2000 habitats and species, European member states have to take action to alleviate the problem of nitrogen deposition (Council of the European Union, 1992). Among the regions in Europe with the highest amount of nitrogen deposition are Denmark (Ellermann et al., 2018), the Netherlands (Kros et al., 2013), the German state of Lower Saxony (Wagner et al., 2017) and the Belgian region of Flanders (De Pue et al., 2017), each characterized by a high density of livestock. In the Netherlands, the national government developed the Programmatic Approach to Nitrogen (Bouwma et al., 2018). The goal of this integrated policy program is to ensure that the European nature objectives are achieved, while at the same time leaving room for economic development (Luesink and Michels, 2018). General emission abatement and site-specific management and restoration measures create room for deposition: part of the reduction in nitrogen deposition is balanced out to permit livestock farms (Luesink and Michels, 2018; Schoukens, 2017). However, the Dutch Council of State ruled against the Programmatic Approach to Nitrogen, rendering the permitting of nitrogen emitting activities highly insecure and sparking a nitrogen crisis in the Netherlands (Stokstad, 2019).

Flanders, the region of Belgium that neighbors the Netherlands, came up with its own Programmatic Approach to Nitrogen, which includes specific restrictions to farms that contribute a high share of the nitrogen deposition in relation to the exceedance of the critical load for a specific habitat. The policy targets agricultural point emissions from animal housing and manure storage. If the nitrogen deposition attributable to a farm amounts to more than 50 % of the habitat’s critical load, it cannot acquire a permit, while farms contributing 5–50% of the critical load can only be licensed under specific conditions, such as a guarantee that the NH₃ emission does not increase (De Pue et al., 2017). Although it is also an important source of agricultural ammonia emissions, the policy does not entail similar spatially-differentiated restrictions to manure application.

In this study, we evaluated the effectiveness and efficiency of this spatially-differentiated policy on the level of individual farms and habitats in Flanders, using a spatially explicit integrated modeling approach described by De Pue et al. (2019). Furthermore, we simulated two additional scenarios that are more effective in regard to deposition in protected habitats. Our model can be used to compare the emission abatement efforts between different livestock subsectors, and the effects on different habitat types protected within the Flemish Natura 2000 network, revealing disparities on these two levels. While the model reported by De Pue et al. (2019) enabled simulating emission abatement measures of individual stables in a spatially-explicit way, the extension of the model presented in this paper allows different policy options to be compared, in order to assess the effectiveness on the level of different Natura 2000 areas, habitat types and even individual receptors.