Call for Data for Nitrogen and Sulphur Critical Load Functions (N & S CLFs) Coordination Centre for Effects (CCE) of the ICP Modelling & Mapping (ICP M&M) of the Working Group on Effects (WGE) J-P Hettelingh, M Posch, J Slootweg CCE WS and ICP M&M TF, 7-10 April 2014, Rome

Reasons for a Call for Data: 1. Change in EMEP deposition grid 2. Requests for update by some NFCs (e.g. due to improved national knowledge) 3. New (policy-driven) emphasis on biodiversity

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Ad 1: EMEP N and S depositions now on a longitude-latitude grid: Grid cells of size ½⁰ × ¼⁰, i.e. ~28 km (at 60⁰N) × ~28km  the “28 km grid” Ad 2: Inter alia, opportunity to provide (better) CLs for Natura2000 (and other protected) areas Size of grid cell as function of latitude:

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Reasons 1 and 2 sufficient for a Call for Data (to maintain up-to-date CL-DB for policy support) However, biodiversity aspects ever more relevant Thus, biodiv-related CLs are encouraged In the following: sketch of a possible way to derive biodiv-related N & S critical load functions

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Level 0: - CL nut N is determined from a critical [N] (or empirical CL) related to (be avoided) biodiv-change - Acidity CL function is derived for a (e.g.) critical pH related to (be avoided) biodiv-change  CLs for acidity and nutrient N combined into a CL function of N and S (dark grey area)

CCE WS and ICP M&M TF, 7-10 April 2014, Rome New Level: Derive N and S CL function from (your favourite) biodiversity model … e.g. PROPS, MultiMOVE, BERN, Veg, …, empirical, … … e.g., along the following lines (using PROPS) …

CCE WS and ICP M&M TF, 7-10 April 2014, Rome PROPS model summary: Probability y for occurrence of a plant modelled as: with a i,j = a j,i for all i,j. Number of variables x i is n = 4 (normalized/log-transformed) : soil solution pH and [N], precipitation, temperature. Probability y obtained as: The 15 coefficients for many plant species are derived from relevés with both biotic and abiotic observations and extrapolated …

CCE WS and ICP M&M TF, 7-10 April 2014, Rome PROPS DataBase: Isolines of occurrence probability for single species (in [N]-pH plane): Temp and Precip fixed.. However, single plants rarely used …

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Example for an EVM vegetation unit Scaled prob. to get all species... But we need relationship with N dep and S dep 

CCE WS and ICP M&M TF, 7-10 April 2014, Rome The same as function of N and S deposition: Computed from physico-chemical site characteristics and steady-state model (here: SMB) Chose a “critical” (“optimal”?) N dep -S dep range 

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Apply limiting/critical/acceptable value of prob/poss/index, e.g.:

N & S Critical Load Function: … or …  [can there by too little S and/or N deposition?]

N & S Critical Load Function: Entire grey area (dark+light) defines N & S CLF, i.e. area of non-exceedance … simplify … 

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Polygons need not be convex, but must be monotonous! [ N1 ≤ N2 ≤ N3 ≤ … and S1 ≤ S2 ≤ S3 …] Simplify to polygon with a few (<10) nodes, e.g.:

CCE WS and ICP M&M TF, 7-10 April 2014, Rome No! Not allowed: i.e. deposition increase may not lead to non-exceedance!

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Summary for Call4Data: 1. Cheap version: Convert existing CLs to 0.10⁰×0.05⁰ Lon-Lat-grid and CLaci+CLnut to 4-point N & S CLFunction 2. Better version: Revisit/update existing CLs, consider biodiv criteria and follow step 1 3. Ambitious version: Use (steady-state or dynamic) biodiv model to derive N & S CLF and follow step 1

CCE WS and ICP M&M TF, 7-10 April 2014, Rome Thank You! … Comments?  Questions? 

CCE WS and ICP M&M TF, 7-10 April 2014, Rome

Choice of probability/indicator: Product of probs. (geometric mean): Arithmetic mean: