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1. Definition
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Name
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GRAZING
INTENSITY
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Brief
definition
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Grazing
intensity in a silvo-pastoral environment is defined
as a value included between 0 and 1, obtained as r2
relative to a direct correlation between the level
of vegetation cover (%) and the livestock load (animal
heads/ha per year) The value represents the contribution
of grazing to the level of pressure vegetation is
subjected to.
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Unit of measure
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A-dimensional, values
between 0 and 1.
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2.
Position within the logical framework DPSIR
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Type
of Indicator
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Pressure.
Provides an estimate of the degree of intensity with
which a livestock load which is not commensurate to
the productive potential of the area, triggers and
accelerates the process of degradation and desertification.
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3.
Target and political pertinence
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Objective
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The
objective of the indicator is to establish to what
extent grazing is responsible for the advanced state
of degradation occurring in various semi-natural ecosystems
of the Mediterranean region, with particular reference
to the Psilotires mountain in Crete, where it has
been tested.
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Importance
with respect to desertification
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Overgrazing
can cause degradation of soil and vegetation. Therefore,
the intensity of grazing can serve as an index of
environmental pressure. Its importance within the
framework of sustainable development is linked to
the possibility of becoming a tool to define a model
for an agro-silvo-pastoral system compatible with
the productive potential of the land.
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International
Conventions and agreements
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The
UNCCD emphasizes the fact that combating desertification
must be tackled within the general framework of actions
to promote sustainable development.
Within
Agenda 21 grazing intensity is relevant to Chapter
12 - Management of fragile ecosystems: combating desertification
and drought.
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Secondary objectives
of the indicator
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4.
Methodological description and basic definitions
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Definitions
and basic concepts
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This
is an indicator measuring how grazing influences vegetation
cover, modifies the plant community, influences diversity
of fauna and exposes soil to erosion. Grazing has
multiple effects on the agro-ecosystem. Animals defoliate
vegetation and consequently influence growth, the
strength and the reproduction of plants and the composition
of species as well as vegetation cover and biomass,
while at the same time they trample the ground, compacting
it, reducing infiltration rates and increasing surface
flows. All these effects, however, are minor and thus
reversible if the intensity of grazing is low or moderate.
Conversely, they become major and irreversible if
the intensity of grazing is very high.
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Benchmarks
Indication of the values/ranges of value
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Methods
of measurement
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To
calculate the indicator, data relative to the type
and extent of vegetation cover is required, as well
as on the effective livestock load. It is necessary
to draw-up a map of the various classes of ground
cover of the area under study. To determine the real
load the number of heads of animals of the different
species must be known, as well as the grazing management
system, and the needs in terms of feed.
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Limits
of the indicator
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One
limit derives from the fact that overgrazing in itself
can only partly explain degradation processes due
to pastoral activity and that for the remaining part
other human activities must be taken into consideration,
especially fires. A second limit is that this indicator,
since it was elaborated in the context of traditional
silvo-pastoral systems wherein external inputs are
very low, requires adaptation to be applicable to
less extensive systems.
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Linkages
with other indicators
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Overgrazing
on its own can only partly explain the process of land degradation.
This means that to define a sustainable model for an agro-silvo-pastoral
system other indicators have to be taken into consideration
pertaining to land degradation, climate, vegetation (Fire risk in this context appears to be the indicator
best able to complement grazing intensity to explain degradation
of vegetation) and socio-economic conditions.
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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
relative to the type and degree of forest vegetation
cover; data relative to the livestock components,
the livestock feeding systems, the pasture management
system.
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Data
sources
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Aerial
photographs; Corine Land Cover: scale 1:100000 available
for the entire European area.
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Availability
of data from national and international sources
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Aerial
photographs and land cover maps, if they exist, are
readily available at a relatively low cost, while
data gathered by means of investigating livestock
farmers is more costly.
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6.
Institutions that have participated in developing the indicator
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Main
institutions responsible
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This
research was conducted at the Chania Mediterranean
Agronomical Institute, Crete, for the MEDIMONT project
(coordinated by Dr. M. Dubost, ICALPE) with the financial
support of the European Commission (DG XII - EVSVC1910045)
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Other
contributing organizations
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7.
Additional information
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Bibliography
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Papanastasis
V.P., 1998. Grazing intensity as an index of degradation
in semi-natural ecosystems: the case of Psiloirtes
mountain in Crete. Proceedings of the International
Seminar held in Porto Torres, Italy 18-20 September
1998: pp. 146-158.
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Other
references
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Contacts
Name and address
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Prof.
Vasilios Papanastasis
Laboratory of range Science, Faculty of Forestry and
Natural Environment - Aristotle University, 54006
Thessalonika, Greece.
Tel:+30 31 9988933
Fax:+30 31 998886
E-mail: vpapan@for.auth.gr
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