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Walllingford 2017

33rd TF M&M meeting, Wallingford (UK), 4-6 April 2017

The 33rd Task Force meeting of the ICP Modelling and Mapping of Critical Loads and Levels and Air Pollution Effects, Risks and Trends (ICP M&M) was hosted by the Centre for Ecology & Hydrology (CEH) in the United Kingdom (Wallingford, 4-6 April 2017)

The objectives of the meeting were:

1. CCE and NFC presentations and discussions regarding the work and results of the Call for Data 2015-2017
2. Update on experimental and modelling results of abiotic and biotic changes due to air pollution and climate change
3. Review of the Mapping Manual
4. Progress under the LRTAP Convention in relation to the workplan and 3rd joint meeting of the EMEP Steering Body and Working Group on Effects

57 delegates from the following 23 countries participated to the meeting: Austria, Canada, Croatia, Czech Republic, Denmark, France, Germany, Italy, Iceland, Latvia, Lithuania, Norway, P.R. China, Poland, Russia, Serbia, Spain, Sweden, Switzerland, The Netherlands, United Kingdom, USA.

The ICP Vegetation, the ICP Waters, the ICP Forests, the Joint Expert Group on Dynamic Modelling and the Coordination Centre for Effects (CCE) were also represented.

The meeting consisted of 5 topical sessions of which the presentations can be downloaded for your information (see agenda and links below). Draft minutes of the meeting will be made available in due course on this site.

Further information can be obtained from the Task Force chair (Dr. A-C Le Gall) and from the head of the Coordination Centre for Effects (Dr. J-P Hettelingh).


Tuesday 4th April 2017

Opening of the 33rd TF and Key Note Session



Chair: Jane Hall

9:00 -9:15

Registration and mounting of posters


Welcome to CEH

Prof. Rosemary Hails,

Director of Biodiversity and Ecosystem Science at CEH.


Welcome from Defra

Prof. Ian Boyd, Defra Chief Scientific Advisor


Objectives of the meeting,

On the status of the CCE

Anne-Christine Le Gall/

Jean-Paul Hettelingh

10:00 - 10:30


Taking stock – long term trends and trajectory to recovery

Prof David Fowler, CEH

10:30 -11:00

Coffee break and Poster session in the presence of poster authors




Topic 1: Result of the Call for Data 2015-2017

Chair: Jean-Paul Hettelingh


CCE compilation and analysis of NFC submissions following the call for data 2015-2017

Jaap Slootweg and Max Posch




Upscaling calculations of biodiversity-based Critical Load functions for UK habitats.

Ed Rowe, Susan Jarvis, Jane Hall


Critical Loads for Biodiversity at the French territory scale using ForSafe-Veg-Ecoplant and PROPS modelling: converging issues?

Rizzetto S., Kuhn E., Gégout J.C., Belyazid S., Haunold S., Probst A.


Exploring critical loads for biodiversity for Norwegian birch forest sites

Kari Austnes


New Results of Critical Load Calculation including Biodiversity in Germany

Hans Dieter Nagel



Tuesday 4th April 2017…Contd

Topic 2: National contributions to effect-based work (under the LRTAP Convention, including the call for data)

Chair:  Anne Christine Le Gall

14:15 - 14:35

Current status of UK ecosystems[i]

Jane Hall

14:35 - 14:55

Update of Swiss critical loads including biodiversity as criterion

Dani Kurz and Beat Rihm

14:55 - 15:15

Coupling climate change and air pollution impacts on forests: un update

Alessandra De Marco


Historical trends in nitrogen and sulphur deposition in the UK: 1800 to present

Ulli Dragosits

15:35 - 15:55

Discussions on Topics 1 and 2

15:55 - 16:10

Coffee break and Poster session

16:10 - 16:30

Validating space-for-time substitution for N deposition[ii]

Lukas Kohli

16:30 - 16:50

Pressure, midpoint and endpoint metrics of N pollution: current and proposed metrics

Ed Rowe, Jones L, Dise NB, Evans CD, Mills G, Hall J, Stevens CJ, Mitchell RJ, Field C, Caporn SJ, Helliwell RC, Britton AJ, Sutton M, Payne RJ, Vieno M, Dore AJ & Emmett BA

16:50 – 17:20

biodiversity critical loads for Irish habitats

Julian Aherne




Wednesday 5th April 2017

Topic 3: Experimental and modelling results of abiotic and biotic impacts of air pollution and climate change

Chair: Ed Rowe

9:00 - 9:20

N-induced changes in root litter decomposition: links to soil parameters and plant species composition[iii]

Seraina Bassin, Ulrike Zell, Matthias Volk, Jürg Fuhrer

9:20 – 9:40

Arbuscular Mycorrhizal Fungus interactions under climate change in mountain regions: preliminary results[iv]

Anna-Lena Wahl

9:40 – 10:00

An application of dynamic modelling to produce site-specific critical loads[v]

Chris Fields, Ed Rowe, Rob Kinnersley and Sarah Watkins

10:00 - 10:20

Modelling the concentration of NH3 and exceedance of the critical level in the UK

Anthony Dore

10:20 - 10:40


10:40 - 11:00

Coffee break and Poster session in the presence of poster authors

11:00 - 11:20

Latest developments on VSD+ - PROPS modelling

Gert Jan Reinds

11:20 - 11:40

Effect of nitrogen deposition and climate change on plant species occurrence: the PROPS model.

Wieger Wamelink

11:40 - 12:00

Recent advances in the application of VSD chain of models on 5 Italian forest sites

Maria Francesca Fornasier

12:00 - 12:20

Analysing the distribution over abiotic parameters, of plant species occurrence

Jaap Slootweg


Critical loads for biodiversity and exceedances using the CCE background data base

Maximilian Posch and Jean-Paul Hettelingh

12:40 - 13:00

Discussion and Task Force conclusions and recommendations on Topics 2 and 3

Anne-Christine Le Gall

13:00 - 14:00



Topic 4: Mapping Manual issues, WGE - and ICP progress

Chair: Anne Christine Le Gall


Update on WGE and Convention issues

Jesper Bak (vice-chair of the WGE)


Review of (and discussion on) the ICP M&M mandate[vi]

Anne Christine Le Gall


Update on ICP Vegetation activities, including Chapter 3 of the Modelling and Mapping Manual - ozone critical levels for vegetation

Harry Harmens


Outcomes of the N-immobilisation workshop in Olten[vii]

Reto Meier


Discussion on Topic 4


Coffee break and Poster session in the presence of poster authors


Effects of Climate Change and air pollution (EMEP) on forest defoliation (ICP) - data base for indicator(s) development

Slavissa Popovic


Update on ICP Waters activities

Kari Austnes


Discussion & Task Force conclusions and recommendations on Topic 4

Anne-Christine Le Gall


Thursday 6th April 2017

Topic 5: Progress under the LRTAP Convention and ICP M&M work plan

Chair: Anne-Christine Le Gall

9:00 - 9:20

Status of ICP Forests

Andreas Schmitz

9:20 - 9:40


Critical Loads, Deposition, and Exceedances in the United States – Critical Load Mapper Tool

Jennifer Phelan

9:40 - 10:00

Highlights on Recent Advances in Critical Loads Research in the U.S.: New Critical Loads, Methods, Models, and Online Tools

Christopher Clark


Global Mapping of Total Atmospheric Deposition in Support of Critical Loads: Results of a World Meteorological Organization Workshop[viii]

Silvina Carou

10:20 - 10:45

Tour de Table on national progress in the field of

effects-based policy support in general and ICP M&M workplan issues in particular

All NFCs or country representatives

10:45 - 11:00

Coffee break and poster session


11:00 - 11:30

Status of the ICP M&M and its Programme Centre and Proposed contributions to 3rd joint session of EMEP and WGE (Geneva, Sept. 2017)

Anne-Christine Le Gall

11:30 - 11:45



11:45 - 12:30

Task Force Conclusions on topic 5;

Draft ICP M&M minutes of the 33rd TF M&M;

Adoption of the draft minutes and closure of the 33rd ICP M&M Task Force meeting

Anne- Christine le Gall







(Poster sessions are combined with coffee breaks)

Biodiversity critical loads for Irish habitats: preliminary results

Julian Aherne

Atmospheric N deposition, O3 and climate interactive effects in Mediterranean ecosystems

Héctor García Gómez


Accounting for forestry practices in Swedish critical loads calculations

Filip Moldan




















- Non-registered last-minute Posters, e.g. addressing ecosystem effects of air pollution including interactions with other policies

- Posters to backup oral presentation





Endnotes of short summaries/abstracts of presentations, when provided by the speaker(s):

[i] Jane Hall (Topic 2): Summarising the current exceedances of critical loads of acidity and nitrogen for UK broad habitats and for UK Natura 2000 sites, and on exceedance of critical levels of ammonia. 

[ii] Lukas Kohli (Topic 2): In Switzerland possible relationships between N deposition at high spatial resolution and plant survey data from the Biodiversity Monitoring (BDM) were analysed. So far the analyses related spatial variation in N deposition with biodiversity measures at a given time. This has led to quantitative exposure-response relationships for two habitats (EUNIS E2.3 and F2.2) and the relationships were used to make predictions about the temporal loss of biodiversity due to N deposition (Roth et al. 2015). This approach is known as space-for-time substitution. The increasing temporal coverage of the BDM data now allows to compare predictions using the space-for-time substitution with real temporal changes in plant richness. We present new findings form the BDM, relate them to our approach and would like to discuss future avenues of gradient study analyses with the experts of ICP M&M.


[iii] Seraina Bassin, Ulrike Zell, Matthias Volk, Jürg Fuhrer (Topic 3) : Carbon and nitrogen cycling as well as their immobilization in soils is determined by litter decomposition rates, which in turn are influenced by litter quality and edaphic/climatic factors. Although dominant plant inputs into soil in grasslands are belowground, little is known about the effect of elevated nitrogen (N) deposition on root decomposition.

A reciprocal transplantation experiment was set up to distinguish effects of altered litter quality from N effects on edaphic conditions. This was done in a long-term experiment, in which 36 turf monoliths from a subalpine pasture were exposed for six years to elevated N (+50 kg N ha-1 yr-1, N50) or remained as control (N0). In the seventh year, litter bags containing roots either from N0 or from N50 monoliths were buried for three months in the top soil layer of both the N0 and N50 monoliths.

Root litter mass loss was significantly increased by +15% by N deposition. Moreover, consistent positive correlations were found for decomposition of the two litter types with pH (Pearsons’ correlation: 0.5 and 0.65 for N0 and N50 litter respectively) - probably due to better nutrient availability at higher pH - and with sedge abundance (Pearsons’ correlation: 0.65 and 0.68 for N0 and N50 litter), but only in N50 monoliths. This suggests that sedge abundance, being up to 300% higher in N50, was a key driver for the observed increased root mass loss in N50 monoliths.

As a result of shifts in species composition and individual plants’ physiological adaptation, chemical composition of roots was significantly altered by the N addition (C:N ratio (-6%), P concentration (-8%), K concentration (-31%), Ca concentration (-21%), ADL:lignin ratio (-12%)). These changes were of minor importance for litter decay in N0 monoliths. However, strong positive correlations between P and K concentration, respectively and mass loss in N50 plots explain why highest decay rates occurred when P/K-rich N0-litter was introduced into N amended, sedge-dominated monoliths.

These results show that elevated N deposition may increase root decomposition rates primarily by changing edaphic conditions through shifts in species composition. Under such conditions, likely due to P and K co-limitation of the decomposer community, litter chemistry gains in importance.

[iv] Anna-Lena Wahl (Topic 3): Preliminary, new, results on AMF-plant interactions in mountain ecosytems under climate change as well as extra cellular enzyme activities in the soil.

[v] Chris Fields et al. (Topic 3): Critical loads for acidity and nutrient nitrogen represent the main policy tool to control air pollution impacts at protected sites, yet there is evidence from gradient surveys that many species are lost below the critical load. This may be because pollutants and their effects can accumulate over many years. Dynamic modelling may offer some solutions to this problem by enabling site-specific critical loads to be calculated, thereby, customising the pollutant response through the addition of a temporal element which considers pollutant accumulation.

As part of their operating permit conditions, operators of some UK Electricity Supply Industry (ESI) power stations and refineries were required to undertake a period of monitoring at key N2000 protected sites that were potentially vulnerable to acidification and eutrophication. This study uses monitoring data collected by CEH as part of this and focusses on Skipwith Common, a SSSI heathland site in North Yorkshire. At around 13 kg N ha-1 yr-1, site monitored deposition is at the low end of the heathland critical load range for nutrient N yet there is evidence of acidification, soil CN is low and leachate N is high suggesting N saturation. Vegetation condition also appears poor with a low occurrence of Common Standards Monitoring (CSM) positive indicator forb species and some bryophytes present have been associated with high N deposition in survey work.

Here, we apply the VSD+ model and the MADOC-MultiMOVE model chain to calculate site-specific critical loads. We also test a new critical limit for biodiversity based on the habitat suitability for 31 CSM positive indicator species and investigate the impact of pollutant reduction and climate change scenarios on habitat suitability. Results suggest that the site will fail to meet future conservation objectives even, under a pollutant reduction scenario of 20%, and highlights the need to consider more invasive management practices at many of our protected sites.

[vi] Anne-Christine Le Gall (Topic 4): During the Joint meeting of the Extended Bureaux of the EMEP Steering Body and of the Working Group on Effects (Geneva, 20-23 March 2017) a request was made for updating mandates for International Cooperative Programmes (ICPs), the Task Force on Health (TFH) and the Joint Expert Group on Dynamic Modelling (JEG). A draft of the mandate for ICP Modelling & Mapping activities (distributed) is proposed and NFC comments are welcomed.

[vii] Reto Meier (Topic 4): Following up on a proposal from Germany for revising the calculation of nitrogen immobilisation the Task Force of ICP Modelling and Mapping discussed this topic at its 2016 meeting in Dessau. The Task Force concluded that the topic required further expert discussion before making major changes to the corresponding chapter of the Mapping Manual.
A workshop for discussing long-term N immobilisation organized by Switzerland was held in Olten, Switzerland on 23rd and 24th February 2017. Interested parties were invited to contribute to this workshop by presenting their assessments of long-term N immoblisation and/or by providing soil data (to be) used for evaluating this question.

Draft Conclusions of this workshop are summarized as follows:

Based on literature review and an evaluation of German, French and Swiss soil data: Moderate to high net N immobilisation rates (3 to 100 kg N ha-1 a-1) have been described for young soils. With increasing soil development and age N immobilisation decreases exponentially and reaches rates below 1 kg N ha-1 a-1 after a few hundred to a few thousand years, depending on bedrock, vegetation and climate. N immobilisation drops down to values close to zero if soils approach a dynamic equilibrium state. It was highlighted that current observations of N immobilisation in soils (e.g. from experiments, inventories) are a present day snap shot influenced by anthropogenic processes, management or natural short term disturbances. Such short term changes cannot be taken as basis for N immobilisation, because they are transient and do not reflect critical load conditions. Taken recent scientific results into account specific changes to the wording of the Mapping Manual chapter V. are proposed (see workshop report distributed separately)


[viii] Carou Silvina (Topic 5): The presentation summarizes key presentations, conclusions and recommendations from a WMO workshop that took place on 28 Feb to 2 March, 2017. The purpose of the workshop was to assess the feasibility and path forward for using measurement-model fusion techniques to map total atmospheric deposition on a global scale for specific atmospheric chemicals including sulfur, nitrogen, base cations and ozone.