Federal Department of the Environment, Transport, Energy and Communications DETEC Federal Office for the Environment FOEN CCE Call for Data , Swiss activities - Exposure-response relationships - Critical Loads for Nitrogen - Dynamic Modelling Beat Achermann (Federal Office for the Environment) Daniel Kurz (EKG Geo-Science) prepared in cooperation with Lukas Kohli (Hintermann & Weber AG) Tobias Roth (Hintermann & Weber AG) Beat Rihm (Meteotest) CCE Workshop, ICP M&M Task Force Meeting, 7-10 April 2014, Rome Air Pollution Control and Chemicals Division

2 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Sites considered for exposure-response relationships and dynamic modelling Biodiversity Monitoring (BDM) Species Diversity in Habitats About 1500 plots of 10 m 2 (E2.3) and (F2.2) selected from BDM sites Sites from Intercantonal Forest Survey Network (Institute for Applied Plant Biology IAP)

3 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Mean nutrient indicator values of plants Basis: Nutrient indicator value of each plant species (Landolt et al. 2010) 1very nutrient-poor 2nutrient-poor 3moderate nutrient-poor to moderate nutrient-rich 4nutrient-rich 5very nutrient-rich to over-rich Examples: 1Vaccinium oxycoccos (swamp cranberry) 2Arnica montana (Arnica) 3Lilium martagon (Turk‘s cap lily, Martagon) 4Rubus fruticosus (Blackberry) 5Urtica dioica (Stinging nettle) } } oligotrophic species eutrophic species

4 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Modelled nitrogen deposition 2010 Considered N compounds:- wet deposition of NO 3 -, NH dry deposition of gaseous NH 3, NO 2, HNO 3 - dry deposition of particulate NO 3 - and NH 4 + (secondary aerosols)

5 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Applied method for statistical analysis Number of plots: 133 for mountain hay meadows (EUNIS E2.3) 37 for (sub)alpine scrub habitats (EUNIS F2.2) GAM (Generalized Additive Model): Response variable: species richness:- all species - oligotrophic species (N indicator values 1 and 2, according to Landolt et al. 2010) Explanatory variables: - N deposition (kg N ha -1 yr -1 ) Confounding variables considered in the model: - Altitude (m a.s.l.) - Exposition (north, south, west, east: o ) - Slope inclination (degrees) - Precipitation (mm, annual average) - Indicator value R for soil reaction (mean indicator value of recorded plants, according to Landolt et al. 2010) - Indicator value F for soil moisture (mean indicator value of recorded plants, according to Landolt et al. 2010)

6 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Exposure-response relationships for mountain hay meadows (E2.3) all speciesoligotrophic species Predicted species richness as a function of N deposition after adjusting for effects of confounding variables

7 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Exposure-response relationships for (sub)alpine scrub habitats (F2.2) all speciesoligotrophic species Predicted species richness as a function of N deposition after adjusting for effects of confounding variables. Similar exposure-response relationships for all species and for oligotrophic species, since on average 79 = 13% of all species belong to oligotrophic species.

8 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Exposure-response relationships in scenario analysis on „no net loss of biodiversity“ (1) Observation-based quantitative exposure-response relationships for mountain hay meadows (E2.3) and sub(alpine) scrub habitats (F2.2) available for use in scenario analysis on „loss of biodiversity“. Applicability: in montane and (sub)alpine areas In areas < 800 m a.s.l.: use grassland exposure-response function according to Stevens et al (Env. Poll.) Differentiation between total species richness and species richness of oligotrophic species possible. The latter deserve special protection. Recommendation: Use new exposure-response relationships, especially also those covering oligotrophic species, in the assessments for the Guidance document on health and environmental improvements using new knowledge, methods and data (ECE/EB.AIR/2013/8)

9 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Exposure-response relationships in scenario analysis on „no net loss of biodiversity (2) Caution when applying observation-based exposure- response relationships in scenario analysis Not sure whether species richness will recover along the quantitative exposure-response curve in case of N deposition reduction: Caution when using results from spatial assessments for assessing developments on the time-scale. Quantitative exposure-response curve probably not valid beyond the N deposition range with observed effects. Application in the N deposition range < 5 kg N ha -1 yr -1, mainly in the case of a very steep curve like the one for oligotrophic species in mountain hay meadows, might lead to very unrealistic „no net loss of biodiversity“ results if a very low background deposition < 1 kg N ha -1 yr -1 is taken as reference.

10 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Observation-based exposure response relationships and Critical Loads for Nitrogen for mountain hay meadows (E2.3) Current empirical Critical Load for Nitrogen for mountain hay meadows (expert workshop Noordwijkerhout 2010) 10 – 20 kg N ha -1 yr -1 (reliability: expert judgement) Proposed adjusted empirical Critical Load for Nitrogen: Indication of exceedance 10 – 15 kg N ha -1 yr -1 decrease total species richness 5 – 10 kg N ha -1 yr -1 decrease species richness of oligotrophic species

11 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Observation-based exposure response relationships and Critical Loads for Nitrogen for (sub)alpine scrub habitats (F2.2) Current empirical Critical Load for Nitrogen for (sub)alpine scrub habitats (expert workshop Noordwijkerhout 2010) 5 – 15 kg N ha -1 yr -1 (reliability: quite reliable) Proposed adjusted empirical Critical Load for Nitrogen: Indication of exceedance 5 – 10 kg N ha -1 yr -1 decrease total species richness and species richness oligotrophic species

12 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Critical Loads for Nitrogen vs Critical Levels for Ammonia – Protection considerations Species-rich meadows and pastures: CLN emp : 8-20 kg N ha -1 yr -1 CLeNH 3 : 2 µg NH 3 m -3 Raised bogs: CLN emp : 7 kg N ha -1 yr -1 CLeNH 3 : 1 µg NH 3 m -3 Fens: CLN emp : kg N ha -1 yr -1 CLeNH 3 : 2 µg NH 3 m -3 Forests: CLN: SMB CLeNH 3 : 2 µg NH 3 m -3

13 CCE Call for Data , Contribution of the Swiss National Focal Centre Beat Achermann Areas of selected ecosystems with exceedances of CLN and CLeNH 3 in 2010 Considering Levels and Loads the priority target should be non-exceedances of Critical Loads for Nitrogen Ecosystem Critical Load (CLN) % area with exceedances Critical Level (CleNH 3 ) % area with exceedances Raised bogs96 %54 % Fens80 %13 % Species-rich meadows and pastures 31 %2 % Forests94 %19 %