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Methodology to calculate CL for Natura 2000 sites at the country scale

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

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Methodology to calculate CL for Natura 2000 sites at the country scale

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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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