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Methodology for CL Calculation at Natura 2000 Sites in France

Development of a methodology to assess Critical Loads (CL) for French Natura 2000 sites, evaluating ecosystem sensitivity to nitrogen deposition and comparing CL between Ecosystem Units and N2k sites. Presentation covers data review, method development, results, risk assessment, and conclusions.

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Methodology for CL Calculation at Natura 2000 Sites in France

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  1. Methodology to calculate CL for Natura 2000 sites at the country scale Arnaud Mansat1,2, Sophie Leguédois1,2,3, Anne-Christine Le Gall4, Anne Probst*1,2 *anne.probst@ensat.fr 1Université de Toulouse; 2CNRS, EcoLab, Toulouse; 3Now at Inra, LSE, Nancy; 4Ineris

  2. Scientific and political context • Nitrogen “cascade” (Galloway et al., 2003) • Eutrophication of terrestrial ecosystems • Threat for biodiversity • Critical Loads (CLs): • a relevant tool to assess ecosystem sensitivity to eutrophying N • Political context • CLRTAP focus: • Biodiversity, N cascade • European Union focus: • Biodiversity protection: Natura 2000 (N2k) network • Assessment of the threats on N2k sites

  3. Scientific and political context • Interest to assess CL(Neut) on N2k sites • EU Habitat Directive : “maintain or restore to favourable conservation status, habitats and species of wild flora and fauna, listed in the Annexes” • assessing the potential threats from acidification and eutrophication to Natura 2000 network • But current CL methods can not be applied directly at N2k sites • See Hall, 2007; Hall et al., 2007; Tamis et al., 2008 • Decision criterias • Avalaible data analyses, • Mapping procedure Etc…

  4. Objectives • Development of a methodology to assess CL(Neut) for the French N2k sites • First assessment of the sensitivity of French N2k sites to nitrogen atmospheric deposition (CL) • Comparison, at the national scale, of the CL(Neut) computed for the normally used Ecosystem Units (EU) and the N2k sites, respectively

  5. Overview of the presentation • Review of the available data and existing models • Developed method to assess CL(Neut) for N2k sites • Results: CL and exceedance • For N2k sites • Comparison with EU • Risk calculation • Conclusions and recommendations

  6. 1. Available data: French N2k network • French N2k network : rare species or of functionnal interest • 6.8 Mha = 12.4 % of the country • Distribution SPA Special Protection Area (Bird Directive) 32 % (2.2 M ha) SACs Special Area of conservation(Habitat Directive) 37 % (2,5 M ha) Both = 31 % (2,1 M ha) 133 habitat types in SACs (Annexe I) of which 28 forested.

  7. 1. Available data: French N2k network French Natura 2000 network 1 740 sites SACs 1 360 sites SPAs 380 sites Spatialisation Unit=SAC CL Model unit= habitat 916 sites with forest habitats CL for: 72% of SACs with at least one habitat i.e. 53% of N2K sites • Selected sites: focus on forest habitats •  CL models more relevant for these ecosystems

  8. Forest habitats • Detailed information at site level • Area 2.5 smaller than French natural and semi-natural ecosystems Sites of ecological importance But not representative of EU diversity 1 color =1ecosystem ≠ 1 9 1. Available data: French N2k network Forest Ecosystem Unit N2K forest sites habitats Number of forest habitats per N2k sites

  9. 1. Existing models • Mass balance model SMB • Requires data on soil biogeochemistry and hydrology • Empirical model • Relevant to assess the impact of N on biodiversity • Model based on expert knowledge and literature data • CL(emp) by Eunis (European Nature Information System) ecosystem • Achermann and Bobbink (2003) • Coupled biogeochemistry-vegetation model • Focused on biodiversity impact but still in development  Model choice depends on avalaible data

  10. 1. Available data • For SACs • Habitats of Annex I present within the site • No information on soil biogeochemistry nor hydrology • Ecosystem classifications • Cross-references Eunis-habitats from Annex I • Moss and Davies (2002) • But no straightforward correspondence • Computation of empirical and mass balance model for EU • Work of the French NFC since 1992 •  Empirical model

  11. Previous work gives correspondance data between French EU and EUNIS classification Need to link N2K habitat to French Ecosystems and/or EUNIS classification. Define a strategy to determine CLemp for habitats 2. Method: determination of a CL for N2k habitat

  12. N2k habitat EU corresponding to this habitat? Eunis corresponding to this habitat? CL min of mean for corresponding Eunis ND Empirical CL 2. Method: determination of a CL for N2k habitat • Decision rules YES NO Moss & Davies (2002) Assigning CLmin from corresponding EU Party et al. (2001); Leguédois and Probst (2008) YES NO Achermann & Bobbink (2003)

  13. N2K site : possibly multiple Habitats No « intra site » localisation of each habitat Need to define a spatialisation rule to determine CLemp for each site. 2. Method: determination of a CL for a N2k site

  14. 3. Results: CL(emp) for forests Comparative results : N2K vs EU (Ecosystem Unit) for CL(emp) Evaluation of risks : Exceedance calculation Exceedance = Deposition – CL(emp) N2K vs EU : Exceedance at EMEP grid scale

  15. 3. Results: CL(emp) for forests Ecosystem Units (EU) • N2k sites Empirical critical loads for Nnut (eq.ha-1.an-1)

  16. 3. Results: CL(emp) for forests Ecosytem Units (EU) • N2k sites (eq.ha-1.an-1) • N2k forest network globally more sensitive than forest EU • At the spatial unit scale as well as the Emep grid scale • Apparent contradiction with European results Slootweg, CCE workshop 2009

  17. 3. Results: exceedance for forests (AAE) • N2k sites • Ecosystem Units (EU) 60 % exceeded 74 % exceeded Exceedance in eutrophying N by Emep grid (eq.ha-1.an-1)

  18. 3. Results: exceedance for forests (AAE) • N2k more sensitive • mean N2K : 138±171 • mean EU : 76.4 ±123 eq.ha-1.a-1 No Exceedances Exceedance in eutrophying N by Emep grid (in eq.ha-1.an-1)

  19. 3. Results: exceedance for forests (AAE) • Exceedances more important for N2K % EXe = EU exceedances – N2K exceedances EXe <0  N2K more sensitive, EXe = 0  equivalent, EXe>0  EU more sensitive

  20. 3. Results: exceedance 5th percentile or AAE Exceedances calculation : AAE / 5th percentile Same trends for both methods AAE (weighted mean) less sensitive than 5th percentile : 200-700 eq.ha-1.yr-1 N2K EU No Exceedances No Exceedances AAE : mean = 138 ± 170 eq.ha-1.a-1 5th perc. mean = 163 ± 179 AAE : mean = 76.4 ± 123.3 5th perc. mean = 120.8 ±163.2 • Exceedances N2K > EU

  21. 4. Conclusion • Methodology for N2k sites • Modelling unit ≠ spatial unit • No straightforward correspondence between Eunis and Annex I habitats • CL(emp) reference document in Natura 2000 classification would be useful • N2k sites seem more sensitive to eutrophying N than EU • N2k sites and EU not designed for the same purpose • Methodological bias or true difference? • Need to go further : “Ensemble Impact Assesment”

  22. However N2k sites globally threaten by nutrient N EIA method : comparaison the 2 modelling results to evaluate modelling robustness  qualitative evaluation of exceedance Forest habitats evaluation only (53 % of SACs) Comparing french EU and Natura 2000 : 2 risk indicators for 2 levels of protection Need of a unified methodology at European scale to assess Natura 2000 eutrophying impact. 4. Conclusion

  23. Thanks for your attention ! • Acknowledgements Didier Allard, Étienne Dambrine, Jane Hall, Jean-Paul Hettelingh, Katia Hérard, Jean-Paul Party

  24. CLRTAP Chance to Look Rapidly To Arc de Triomphe Paris CL Caroussel Louvre CL Conciergerie Lido SPA: Seine Pont Alma SAC :SAinte Chapelle EUNIS Eiffel Unesco Notre-Dame Invalides Sacré-Coeur EMEP Elysée Montmartre Elysée Panthéon AAE Avenue Montaigne Auteuil Egouts EIA Etoile Ile Cité Arche Défense NFC : Never Forget Concorde Welcome!! Acronyms Paris Tour

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