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1. Definition
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Name
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ORGANIC
MATTER IN SURFACE SOIL (regional scale, RS experimental)
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Brief
definition
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Soil
organic matter is essentially derived from residual
plant and animal material, synthesised by microbes
and decomposed under the influence of temperature,
moisture and ambient soil conditions. It plays a central
role in maintaining key soil functions and is an essential
determinant of erosion resistance and soil fertility.
Decrease of organic matter (OM) is an indicator of
a lowered quality in most soils. Loss of OM means
soil degradation.
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Unit
of measure
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%
OM in top soil layer
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Spatial
scale
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From
target area level to national and Mediterranean wide
scale
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Temporal
scale
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Change
over 5 years
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2.
Position within the logical framework DPSIR
3.
Target and political pertinence
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Objective
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Identification
of areas with prevailing trends of decreasing OM contents
or critically low levels of Soil Organic Matter (SOM),
these soils being most at risk of desertification.
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Importance
with respect to desertification
|
Soil
organic matter decline is of particular concern in
Mediterranean areas. According to the European Soil
Bureau, based on the limited data available, nearly
75% of the total area analysed in Southern Europe
has a low (3.4%) or very low (1.7%) soil organic matter
content. Agronomists consider soils with less than
1.7% organic matter to be at a pre-desertification
stage.
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International
Conventions and agreements
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The
UNCCD emphasises the fact that combating desertification
must be tackled within the general framework of actions
to promote sustainable development. Decrease of OM
is a key factor in accelerating soil erosion and thus
for irreversible land degradation and desertification.
The
European Commission in their Communication "Towards
a Thematic Strategy for Soil Protection" (COM(2002)
179 final) emphasize that the decrease of SOM in European
soils is one of the major threats to European soil
resources and explicitly state that it is of particular
concern in the Mediterranean region.
The
UNCCC pays increasingly attention to the role of SOM
in the context of the global carbon balance and accounting
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|
Secondary
objectives of the indicator
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Contribution
to take into account the role of SOM in the global
carbon balance. Base information can be used to revise
European environmental legislation e.g. regarding
the use of sewage sludge or compost
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4.
Methodological description and basic definitions
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Definitions
and basic concepts
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Typically
% values of organic carbon (OC) are given. OC values
may be converted to OM values by applying a standard
ratio OC:OM of 1:1.7.
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Benchmarks
Indication of the values/ranges of value
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Ranges
of OC values given are:
- high >6.0%;
- medium 2.1-6.0%;
- low 1.1-2.0%;
- very low <1.0%
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Methods
of measurement
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Direct
chemical analyses of OC of soil samples. Only very
limited number of samples available, in most cases
not sufficient to account for the high variability
of OM, especially at regional scales.
Derivation
from available spatially distributed data sets such
as soil type, climate, topography, land cover through
the application of pedotransfer rules.
Remote
sensing contributes in 2 ways. Through provision of
up-dated land cover/land use information (main driver
of OM decline); and through direct estimation from
reflectance images by novel approaches such as chemometrics
approaches applied to image spectra. The latter is
possible in areas where large areas of soil are uncovered
or only marginally covered (<30%) by vegetation
for longer periods, i.e. mainly arable lands and pasture/degraded
garrigue after the summer.
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Limits
of the indicator
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An
insufficient number of reference plots are available
for regular field sampling and chemical analysis as
regards agricultural areas (the situation for forests
is different).
Application
of pedo-transfer rules to existing data bases for
large areas (Europe wide) has so far been limited
to a scale 1:1000000 and more frequent up-dates of
land cover/land use data will need to be derived from
remote sensing in order to increase the frequency
of the assessment in a monitoring and early warning
context.
Recent
attempts to directly assess OC contents from remote
sensing data such as Landsat-TM have been successful
and promising for wider application; however, the
novel algorithms used still have to be considered
pre-operational and still need further validation
and calibration.
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Linkages
with other indicators
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Vegetation
cover rs, Soil erosion, Land
use type
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5.
Evaluation of data needs and availability
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Data
required to calculate the indicator
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Data
required to calculate the indicator includes: soil
type (soil mapping unit), land cover/land use, climate
data, topography. Remote sensing data, such as Landsat-TM,
ASTER is used for DESERTLNKS target areas and MERIS,
MODIS for national and regional scales (NOAA AVHRR
is only for land cover information).
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Data
sources
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For
some countries nation wide sampling campaigns for
analytical work have been performed e.g. Italy.
Data
bases such as the 1: 1000000 European Soil Database,
Corine Land Cover, MARS climate data, etc are available
at the JRC as well as the 1:1000000 Europe wide assessment
of soil organic carbon.
The
required remote sensing data are available at relatively
low cost from existing archives of commercial providers
and public agencies such as ESA, NASA etc.
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Availability
of data from national and international sources
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The
above-mentioned data are accessible at reasonable
costs.
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6.
Institutions that have participated in developing the indicator
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Main
institutions responsible
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Institute
for Environment and Sustainability, DG JRC, European
Commission, Ispra, Italy
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Other
contributing organizations
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7.
Additional information
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Bibliography
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E.
Rusco, R. Jones & G. Bidoglio, 2001: Organic Matter
in the soild of Europe: Present status and future
trends. European Soil Bureau, Soil and Waste Unit,
Institute for Environment and Sustainability; Report
EUR 20556 EN, 14p.
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Other
references
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European
Commission 2002: Towards a Thematic Strategy for Soil
Protection - COMMUNICATION FROM THE COMMISSION TO
THE COUNCIL, THE EUROPEAN PARLIAMENT, THE ECONOMIC
AND SOCIAL COMMITTEE AND THE COMMITTEE OF THE REGIONS
(COM(2002) 179 final)
Joachim
Hill and Brigitta Schuett, 2000: Mapping Complex Patterns
of Erosion and Stability in Dry Mediterranean Ecosystems.
REMOTE SENS. ENVIRON. 74:557-569 (2000) , Elsevier
Science Inc., 2000
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Contacts
Name and address
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EC,
DG Joint Research Centre
Institute for Environment and Sustainability
Stefan Sommer
< stefan.sommer@jrc.it>
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