Nutrient enrichment and pollution related
pressures on agricultural, grassland, heathland
and forest ecosystems
Task 1.8.4.3 Ecosystem pressures
Type of Document:
“Draft Internal Report”
Prepared by:
Christoph Schröder (UMA)
Date:
25. July 2014
Project Manager:
Markus Erhard
Universidad de Malaga
ETCSIA
PTA - Technological Park of Andalusia
c/ Marie Curie, 22 (Edificio Habitec)
Campanillas
29590 - Malaga
Spain
Telephone: +34 952 02 05 48
Fax: +34 952 02 05 59
Contact: etc-sia@uma.es
TABLE OF CONTENTS
1
Introduction ............................................................................................3
2
Goals .......................................................................................................3
3
Input datasets .........................................................................................4
4
Indicator development and results ..........................................................5
4.1
Agro-ecosystems ..............................................................................................5
4.2
Forest ecosystems ............................................................................................9
4.3
Grassland ....................................................................................................... 10
4.4
Heathland and Scrub ecosystems ................................................................... 11
5
Conclusion and outlook ......................................................................... 13
6
Bibliography .......................................................................................... 14
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1 INTRODUCTION
Pollution and nutrient enrichment are one of five drivers of change exerting pressures on
European ecosystems. Nutrient enrichment is a type of diffuse pollution, mainly caused
by nitrogen, but also by phosphorous which has altered nutrient cycling in habitats,
damaging soils and reducing water quality. Signs of nutrient enrichment include
replacement of flowering herbs by competitive grasses and growth of algae in
freshwaters. These changes are often the tip of the iceberg affecting many other species
and reducing biodiversity
Environmental problems related to nitrogen concern all economic sectors and impact all
media: atmosphere, pedosphere, hydrosphere and anthroposphere (Sutton et al. 2011).
Losses of reactive nitrogen to the environment have increased greatly, including nitrate
pollution of water courses and emissions of both ammonia and nitrous oxide to the
atmosphere, with impacts on biodiversity and climate change. A wide range of
assessments have been made regarding nitrogen budgets and its impact on different
media (e.g. the European Nitrogen Assessment). Nevertheless, there has not been so far
a European wide assessment of the pressure exerted by nutrient enrichment to European
ecosystems. With the publication of the European Map of ecosystem type (Banko et al.
2014), the pressure of the different drivers can be related to each ecosystem type and
mapped spatially explicit.
2 GOALS
This report aims to define datasets and indicators most adequate to map the major
pressures on the ecosystems by nutrient enrichment and pollution as well as propose an
approach and workflows to assess and map these pressures. This assessment focusses
on grassland, heathland and scrub, forest and agro-ecosystems.
The work builds on the major drivers and pressures identified in ETC-SIA´s 2013 report
Towards a Pan-European Ecosystem Assessment Methodology (task 222_5_2) 1,
particularly the nutrient accounts developed within this task.
The steps followed to define the indicators are:
•
Check the availability and evaluate the coverage and suitability of data
reported in 2013 report,
•
Analyse their relevance to assess pressures,
•
Select the input datasets, according to their relevance and importance in
contributing to the pressures assessment,
•
Provide a workflow on assessing pressures on affected ecosystems with
selected input data.
After presenting the input data used, the used input data and indicators for nutrient
enrichment are presented for each affected ecosystem. Finally, conclusions from the
methodological approaches are drawn and an outlook is given regarding open and
remaining issues.
For further details, see http://forum.eionet.europa.eu/etc-siaconsortium/library/2013_subvention/222_5_2_ecosystem_assessment/finalreport_pressures-biodiversity/final-report_subtasks_pressures
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3
INPUT DATASETS1
Reference year
(for the
assessment)
2010
(datasets
available for
2000 -2010)
Drivers
Use
Pressure
Indicator
Datasets available
Pollution
Pressure
Nutrient enrichment
Macro-nutrients input
N, P accounts (ETC-SIA) : change in N/P
input in ecosystems in time (kg/h/year)
Pollution
Pressure
Heavy metal
contamination
Accumulation of heavy metals in agricultural
soils
Estimation of heavy metal input and
accumulation (Alterra, ETC-SIA)
2000/2050
Pollution
Pressure
Atmospheric
deposition
Nitrogen atmospheric deposition on natural
ecosystems
N, P accounts (ETC-SIA)
2010 (datasets
available for
2000-2010)
Pollution
Trends in
pressure
Change in nutrient
enrichment
N,P flows (2000 – 2010)
N, P accounts (ETC-SIA) : change in N/P
deposition in ecosystems in time
(kg/h/year)
Table 1: List of indicators used to describe nutrient enrichment and pollution
1
More information of single datasets used in the assessment is available in Annex 1.
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2000 -2010
Note
Only available at NUTS2
level. Elaboration of
disaggregation to NCUs in
progress.
4 INDICATOR DEVELOPMENT AND RESULTS
4.1
Agro-ecosystems
Agro-ecosystems are the ecosystems that are most exposed to nutrient enrichment
due to the direct application of organic and inorganic fertilizers. This is linked with
the essential need for nitrogen to increase food production.
Inputs of macro nutrients (nitrogen), micro-nutrients (e.g. Cu, Zn) and metals (Cd,
Pb) by manure and fertilizer application have led to an increase in crop growth and
soil fertility. Nevertheless, the increased fertilizer application, increased
atmospheric deposition and other pollutant inputs, also have augmented the
accumulation of these nutrients, leading to eutrophication and increased metal
levels, elevating the risk for ecosystems, soil biodiversity and human health.
4.1.1 Nitrogen input
Nitrogen input data were derived from the nutrient accounts developed at ETC-SIA.
The total N r input to agricultural soils includes intentionally applied (organic or
mineral) fertilizer and manure from grazing livestock as well as biological nitrogenfixation and atmospheric deposition:
These data are calculated at a resolution of 1km, using crop and livestock data from
the EEA carbon accounts and statistics and conversion factors from different
sources, mainly based on the OECD & EUROSTAT 20073.
The resulting map (Figure 1) shows areas of intense nutrient pressure in Denmark,
West Germany, Netherlands, Belgium, North-western France, Catalonia and the
Italian Po Valley. The overall share of N input to agricultural soils illustrates the
high importance of manure and mineral fertiliser as pressures to agro-ecosystems.
3
See methodological report from 2013 for further details:
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Figure 1: Nitrogen input to agro-ecosystems for the year 2010.
4.1.2 Trend indicator for nutrient input
Based on the available time series of the nutrient accounts, a trend indicator can be
calculated, assessing and mapping the trend of nutrient inputs during the period
2000-2010. Figure 3 provides an illustration of the difference between the trend
value of the period 2000-2005 and the year 2000. Negative values indicate that the
nitrogen input for the period 2000-2005 is lower than in year 2000, while positive
values indicate an increase of nutrient input after the year 2000. The following
chart (Figure 2) summarizes the workflow of processing of the trend indicator.
Figure 2: Workflow to calculate nutrient input trend indicator.
This trend indicator can be easily be calculated for different time slots if data are
available. It is expected that with the publication of the Corine Land Cover 2012,
new trends can be assessed.
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Figure 3: Nitrogen input of overall trend value of the period 2000-2005
compared to the year 2000
4.1.3 Heavy Metal input
In soils across the EU, inputs of contaminants including metals like copper (Cu),
cadmium (Cd), lead (Pb) and zinc (Zn) are of concern in view of the accumulation
in the terrestrial and aquatic environment. Accumulation in soils and sediments and
consequently increased levels in the aquatic environment can lead to increased
exposure of soil and aquatic organisms conducting to a potential decreased
functioning of the soil or aquatic ecosystem. In order to assess to what extend
current and future levels of metals in soil pose a risk for ecosystem functioning an
integrated assessment at the EU level is essential. This assessment has been done
at NUTS level by Römkens et al. as part of the 2013 methodological report (see
footnote 3). Currently the same assessment is done at the resolution of NitroEurope
Classification Units (NCUs)4 (see Figure 4 for a map example). The results of the
disaggregated data sets are not yet available, hence they have not been integrated
into the present analysis.
NCUs are unique combinations of soil type, administrative region, slope class and
altitude class composed of polygons that are a cluster of 1 km x 1 km pixel.
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Figure 4: Cd input to agricultural soils 2000 (g/ha/yr)
4.1.4 Methodology proposal for indicator integration
The aim of the elaboration of an indicator of cumulated pressures on terrestrial
ecosystems is to estimate the combined effect of nutrient applications and heavy
metal input. This combined image is crucial to identify hotspots of related pressures
and be able to mitigate them.
The indicator creation and related assessment is complex if we take into account
the following questions: What effect should be considered crucial for ecosystem
functioning? How to account for transfer along the food chain where lower ranked
organisms are not affected but accumulation along the food chain will result in
effects in predators or other higher-tier organisms? Which organisms are crucial in
view of ecosystem functioning? How to account for interactions between
contaminants rather than considering single elements? Nevertheless, the proposed
workflow and the proposed indicator (see Figure 5) may provide a first indication of
where critical levels for which ecosystems may be expected.
For the purpose of mapping the degree of nutrient enrichment from both sources
the level of pressure of micro- and macro-nutrients was tried to be estimated, using
different input data. Following-up on the results of the nutrient accounts at 1km
resolution and metals analysis NUTS level, values of each component will be
standardised and classified in three classes (low, medium, high) using thresholds
from expert consultation. Based on this classification, a qualitative indicator can be
proposed as a combination of low to high values of both analyses. The classification
of low, medium and high values could be done on a statistical basis and takes into
account the overall distribution of the data.
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This approach is highly experimental because for pressure assessments, few field
based experimental threshold levels for metals in soil are available and most tests
focus on single species and the use of these thresholds is usually not recommended
for a pressure assessment at the ecosystem level.5 Nevertheless, a first proposal is
made with the following methodology to be enhanced in the future. Particularly the
definition of thresholds is attached with high uncertainties and needs to undergo
critical scientific and technical discussion.
Figure 5: Workflow and proposed indicators for cumulated pressure assessment of
nutrient input
A first map representation of this approach is not presented as its visual results
may be misinterpreted as a given level of pressures. There is a need for better data
and thresholds, particular regarding micro nutrients, in order to be able to present
a consistent map of cumulative pressure of nutrient enrichment in agricultural soils.
4.2
Forest ecosystems
Forest ecosystems are exposed to pollution and nitrogen enrichment mainly
through atmospheric deposition of oxidized and reduced nitrogen. Fertilization takes
place in limited areas of forest plantations, but no general data are available to
estimate the level of pressure of such activities (Smethurst 2009).
Nitrogen atmospheric deposition may affect the health and productivity of European
forests. While increased nitrogen may increase productivity in many terrestrial
ecosystems (which are typically N limited) this is not necessarily desirable in
protected ecosystems, where natural ecosystem function is desired as excess
nitrogen can lead to nutrient imbalances in trees, understory species, nonvascular
plants (lichens), or mycorrhizal fungi; changes in composition of these species; and
ultimately to declines in forest health. Hence, an estimation of the amount of
At least, for the Netherlands a nationwide assessment is available (de Vries et al.,
2008).
5
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nitrogen atmospheric deposition on a European scale is of high interest for further
analysis of impacts on forest productivity and biodiversity. The results from the
nutrient accounts suggest the situation presented in Figure 6.
Figure 6: Nitrogen atmospheric deposition on forest ecosystems.
Taken into account that the critical load for forest ecosystems is defined between
10-20 kg/ha/yr (Bobbink & Hettelingh 2010), depending on the specific forest
habitat a map of high to low pressures was elaborated, reclassifying the absolute
values nitrogen atmospheric deposition, that is depicted in Figure 4 of the report on
Indicators to assess major pressures on woodland and forest ecosystems in Europe.
4.3
Grassland
The mapping of nutrient pressure in grassland habitats includes nitrogen
atmospheric deposition. Depending on the specific grassland ecosystem, the
pressure of nitrogen load is evaluated differently, in terms of critical load. The
following reclassification (Table 2), based on Bobbink & Hettelingh (2010) is an
approximation to evaluate the level of pressure to grassland ecosystems in general,
illustrated in Figure 7:
Charge of nitrogen deposition kg N ha-1 yr-1
5
5 - 10
10 – 20
20 – 30
> 30
Pressure classes
Very low
Low
Moderate
High
Very high
Table 2: Definition of pressures classes for grassland ecosystems
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Figure 7: Level of pressure of nitrogen atmospheric deposition on
grassland ecosystems.
4.4
Heathland and Scrub ecosystems
Heathlands and scrubs are natural ecosystems with only low intensity human use
and management (see report “Indicators to assess major pressures on grasslands
and scrublands ecosystems in Europe” for further analysis of drivers and pressures
on these ecosystems). In terms of pollution and nutrient enrichment, nitrogen
atmospheric deposition is the main pressure at work. Figure 8 illustrates the mean
nitrogen deposition per NUTS 3 regions, indicating those regions with highest levels
N deposition.
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Figure 8: Nitrogen atmospheric deposition on heathland and scrub
ecosystems
In terms of levels of pressure, a pixel based mapping (Figure 9) shows the affected
areas and the level of pressure (the same pressure classes as for grassland
ecosystems were used, based on Bobbink & Hettelingh 2010, ver Table 2). Most
heathland and scrub ecosystems are located in the Mediterranean, but are only
exposed to very low or low deposition levels, while smaller areas in central Europe
and north Italy are highly affected.
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Figure 9: Nitrogen atmospheric deposition on heathland and scrub
ecosystems
5 CONCLUSION AND OUTLOOK
The indicators that shall describe the pressures by nutrient enrichment are based
on amounts of nutrient input, taken into account ecosystem specific thresholds. The
current input data base is sufficient to describe the pressures exerted by nutrients
and other pollutants, given that the input data have a European coverage without
major spatial gaps. The mapping of the indicators shows already some hotspots of
pressures that will require validation with existing local data. Additionally, the
thresholds still require further enhancement via expert consultation.
Apart from these first conclusions, several open and critical issues have to be
tackled in future work on the pressure of nutrient enrichment and pollution to
European ecosystems.
1) Other sources of pollution
The present work does not take into account other sources of pollution than macroand micro-nutrients. Pesticides, ozone deposition and other sources of pollution
have to be assessed regarding the availability of data and the possibility to
integrate them into the assessment methodology.
2) Data validation
Nutrient data on N and P have recently been produced, and are still undergoing
validation in close collaboration with EEA, JRC and other experts in order to produce
a high standard data set. The actual impact of N and P on the soil biodiversity of
the different agro-ecosystems on a European level is a current research topic.
Hence, a Pan-European assessment continues to be an estimation of potential
pressures and impacts.
As mentioned before, data on heavy metal input and accumulation are at the
moment only available at NUTS 2 level. Nevertheless, Alterra is preparing a dataset
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of heavy metal input downscaled to the NitroEurope Classification Units (NCUs)
which will provide a more detailed information about the input and accumulation of
heavy metals on a Pan-European scale. Additionally, the heavy metal assessment is
currently only available for the years 1900, 1950, 2000 and 2050, though some
modelling for 2010 and 2020 is foreseen.
3) Uncertainty regarding nutrient and heavy metal data
The integration of macro- and micro-nutrient budgets, including the partial results
of inputs, into one cumulative pressure index is currently attached with too much
uncertainty as mentioned before. Particularly the definition of thresholds is attached
with high uncertainties and needs to undergo critical scientific and technical
discussion, for as few field based experimental threshold levels for metals in soil are
available and most tests focus on single species and the use of these thresholds is
usually not recommended for a pressure assessment at the ecosystem level. Future
work has to focus on how this uncertainty can be reduced and, hence, a meaningful
indicator calculation can be achieved based on this first proposal.
Finally and linked to the issue of uncertainty, the links of the proposed pressures to
impacts and functional traits of biodiversity are to be analysed very carefully when
it comes to relating degrees of nutrient enrichment on a European scale.
6 BIBLIOGRAPHY
Banko et al. (2014): Map of Ecosustem types V2.0.
Bobbink, R., & Hettelingh, J. (2010). Review and revision of empirical critical loads
and dose-response relationships. Proceedings of an expert workshop. Noordwijkerhout 23-24 June 2010, Bilthoven, the Netherlands, RIVM.
Butterbach-Bahl, K., Gundersen, P et al. (2011): Nitrogen processes in terrestrial
ecosystems. In: Sutton et al. (eds): The European Nitrogen Assessment. Sources
Effects and Policy Perspectives. Cambridge.
De Vries, W., Römkens, P.F.A.M. & Bonten, L.T.C. (2008): Spatially Explicit
Integrated Risk Assessment of Present Soil Concentrations of Cadmium, Lead,
Copper and Zinc in The Netherlands. Water Air Soil Pollut 191:199–215
Grizzetti, B., Bouraoui, F. & Aloe, A. (2007): Spatialised European Nutrient Balance.
Joint Research Centre. European Commission.
Leip et al. (2011): Chapter 16: Integrating nitrogen fluxes at the European scale.
In: Sutton et al. (eds): The European Nitrogen Assessment. Sources Effects and
Policy Perspectives. Cambridge.
OECD & EUROSAT (2007): Gross [Nitrogen, Phosphorus] Balances Handbook.
Simpson, D.,Butterbach-Bahlb, K., Fagerlia, H., Kesikb, M. Skibac, U. & Tangc, S.
(2006): Deposition and emissions of reactive nitrogen over European forests: A
modelling study. Atmospheric Environment. 40 (29): 5712–5726.
Smethurst, P.J. (2010): Forest fertilization: Trends in knowledge and practice
compared to agriculture. Plant and Soil 335 (1-2): 83-100
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Annex 1 Input data: List of datasets used for the development of single
pressure indicators
Name of the data set:
CORINE Land Cover (CLC)
Description of the information content:
CLC provides information related to land use/land cover in the EU. CLC products are based on the photointerpretation
of satellite images by the national teams of the participating countries - the EEA member or cooperating countries. The
resulting national land cover inventories are further integrated into a seamless land cover map of Europe.
Source:
EEA
Link:
http://www.eea.europa.eu/data-and-maps
Policy relevance / legal framework:
European Land use policies/ European biodiversity policies
CONSENT spatial data system:
LULC and Agri-forest
Relevant database information on ecosystems assessment:
CLC data helps providing support for protecting ecosystems, halting the loss of biological diversity, tracking the impacts
of climate change, assessing developments in agriculture and implementing the EU Water Framework Directive.
Spatial coverage:
Variable: EU-27 or EU32
Temporal coverage:
1990, 2000, 2006, 2012 (upcoming)
Resolution:
100 and 250 m
Format:
Raster and vector
Data availability:
Different CLC versions are available on the EEA web site.
Shortcomings / limitations / gaps:
Spatial coverage is variable: coverage in 1990 is low compared to 2000 and 2006. No data for Island, UK, Norway,
Sweden, Finland, Switzerland and Balkans region in 1990. No data for Greece and Switzerland in 2006.
Status of the underlying methodology:
Mature.
Name of the data set:
Nutrient accounts – Methodology development for N and P accounts per ecosystem type
Description of the information content:
Pan-European nutrient accounts presents a yearly picture of the nutrient balances per ecosystem: cropland, forest and
grassland; based on data related to different inputs sources and outputs:
Crops:
- Inputs: inorganic fertilizer, amount of nitrogen and phosphorus originating from manure, atmospheric deposition,
biological fixation (only nitrogen),
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- Outputs: crop uptake, grazed biomass
Forest:
- Inputs: atmospheric deposition, biological fixation (only nitrogen)
- Output: forest fires, timber extraction
Nutrient accounts are based on:
- Data developed in the framework of the carbon account (crops, grazed biomass, etc), including area and yield, at with
1 km resolution, available for 2000-2010 and for EU27.
- Country specific nitrogen and phosphorus excretion coefficients per animal category are available from OECD data.
- National mineral fertiliser application (Eurostat/FIA).
- The annual EMEP MSC-W model results of air concentrations and depositions are available as gridded data from the
EMEP webpage. The EMEP data are already at a 50 km grid resolution and need to be disaggregated to the 1 km grid.
- For forest ecosystems, results from the paper “Deposition and emissions of reactive nitrogen over European forests”
(Simpson et al. 2006) may be used.
- CORINE Land Cover (forest types), HRL forest.
- Annual forest stocks and timber extraction from the carbon accounts.
Source:
ETC-SIA
Link:
No direct link to data
Policy relevance / legal framework:
Nitrogen Directive
CONSENT spatial data system:
LULC and Agri-forest
Relevant database information on ecosystems assessment:
Pressure on agriculture, grassland, and forest ecosystems
Spatial coverage:
EU-27
Temporal coverage:
2000-2010
Resolution:
1 km Grid
Format:
Raster
Data availability:
Data can be requested to ETC-SIA
Shortcomings / limitations / gaps:
Uncertainties arise mainly from the use of country or crop specific conversion factors, coefficients or application rates
that do not reflect regional differences. N fixation for instance may vary highly within a single country between northern
and southern latitudes. The same holds true for some national statistics (i.e. on mineral fertilizer) which present data
gaps that need to be filled.
Data on atmospheric deposition are model based and hence the attached uncertainties must be taken into
considerations. Nevertheless, scientific evidences (e.g. Simpson et al. 2006) suggest that the EMEP data are valid in
reproducing deposition.
Uncertainties still are present as well regarding the input maps of the carbon accounts. Despite the fact that the results
and intermediate results of the accounting task have been reviewed in depth for the purpose of the ecosystem accounts,
they have not been applied to other domains so far. The comparison of the nutrient accounts with external data on
different components of these accounts will highlight as well the quality of the input data.
Most work on nutrient balances has been done for agricultural land (arable land and grassland). Forest ecosystems
have not been treated in such a detail. Nevertheless, atmospheric deposition of N and P on forests are of importance
and a significant input into forest ecosystems. Outputs (mainly timber extraction) are available via carbon account data
sets.
Status of the underlying methodology:
Under validation.
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Name of the data set:
Heavy Metal balances at Regional Scale in EU 27
Description of the information content:
Heavy Metal balances at NUTS 2 level for EU 27 calculated based on Fertilizer input, animal manure, sludge
application, atmospheric deposition, yields, plant metal content, soil properties, metal content in soils, net water loss.
Individual input (leaching rates, plant uptake) and outputs (fertilizers, manures) per type and per heavy metal (Cd, Cu,
Pb, Zn) are calculated, as well as total input and accumulation.
Source:
ALTERRA
Link:
No direct link to data
Policy relevance / legal framework:
Nitrogen Directive, End-of-Waste Directive
CONSENT spatial data system:
LULC and Agri-forest
Relevant database information on ecosystems assessment:
Pressure on agriculture, grassland, and forest ecosystems
Spatial coverage:
EU-27
Temporal coverage:
1900, 1950, 2000, 2050 (2010 foreseen)
Resolution:
NUTS 2 (NCUs foreseen)
Format:
Vector file, table
Data availability:
Data can be requested to Alterra
Shortcomings / limitations / gaps:
Data gaps for Romania. NUTS2 level is very coarse for detailed assessment.
Envisaged improvements: Intended target scale level: NUTS -> NCU (-> 1 km2)
Main, data-related improvements are expected:
Increased number of soil data points (including GEMAS data, n=4000)
Downscaled data on animal numbers at 1 x 1 km
Consideration of compost: national/regional application rates?
Consideration of variability in quality of fertilizer, manure (?) sludge and compost at national level
Status of the underlying methodology:
Mature.
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