1. Definition
Name
|
PERIOD OF EXISTENCE
OF LAND USE TYPE
|
Brief definition
|
The present land
use type, and the period of existence of that land
use type, is important as it is related to cumulative
long effects on land protection or on land degradation.
|
Pine
forested area in the island of Lesvos which remains
under the same type of vegetation for more than
three thousands of years as it is evidenced by
existing historical documents, well protected
from degradation and desertification (photo by
C. Kosmas) |
|
Unit of measure
|
Years
|
2. Position within the
logical framework DPSIR
3. Target and political
pertinence
Objective
|
Contribution to
the definition of the desertification risk of a certain
area.
|
Importance with
respect to desertification
|
The extensive
deforestation of hilly areas and intensive cultivation
with rainfed crops such as cereals, almonds, vines,
and olives in the Mediterranean has already led to
soil erosion and degradation to various degrees in
the last century. The stage of land degradation depends
on the type and the period of existence of land use
type. For example some hilly areas that were under
forest with deep soils were brought into cultivation
of cereals or olives. Under the prevailing management
practices the erosion rates in areas with cereals
are higher than in olive groves. Today several areas
cultivated with cereals for decades or centuries have
degraded appreciably and are now abandoned due to
low land productivity. The loss in land productivity
soon becomes apparent in areas with soils having limiting
subsurface layers, such as petrocalcic horizons or
bedrock. If high erosion rates occur over a long period
the soil depth is drastically reduced and under hot
and dry climatic conditions such areas are desertified.
However, areas cultivated with olives under similar
soil, topographic, and climatic conditions are better
protected from degradation and desertification for
longer periods than areas cultivated with cereals.
|
International
Conventions and agreements
|
The UNCCD emphasizes
that combating desertification must be tackled within
the general framework of actions to promote sustainable
development.
|
Secondary objectives
of the indicator
|
Within the ESA
model: a) investigation of the individual processes
linked to land degradation and desertification, b)
assessment of desertification risk.
|
4. Methodological description
and basic definitions
Definitions and
basic concepts
|
The importance
of a certain type and period of land use becomes apparent
in association with different annual erosion rates
occurring under Mediterranean climatic conditions.
Experimental data for different places within Mediterranean
Europe, as measured under various land uses types,
have shown significant differences in soil erosion
rates. Typical Mediterranean land uses can be graded
in order of decreasing effect on soil erosion as following:
vines, eucalyptus, winter wheat, shrubland and olives.
Specifically, for cereals in the rainfall range of
280 mm per year to 700 mm per year, sediment loss
may fluctuate generally between 15 and 90 t km-2
per year. The erosion rates measured under eucalyptus
plantations ranged from 1.4 t km-2 per
year to 65.6 t km-2 per year. For olives
grown under semi-natural conditions, i.e. with an
understory vegetation of annual plants, a sediment
loss greater than 5.3 t km-2 per year is
uncommon. Greater erosion rates are expected from
soils cultivated with vines and almond trees. The
erosion rates under such crops can range between 67
t km-2 per year and 460 t km-2
per year.
|
Benchmarks Indication
of the values/ranges of value
|
- <5 years,
- 5-10 years,
- 10-20 years,
- 30-50 years,
- >50 years
|
Methods of measurement
|
By contacting
the land user or by interpretation of a series of
aerial photographs.
|
Limits of the
indicator
|
No limits
|
Linkages with
other indicators
|
Land
use type, Vegetation
cover, Rainfall, Soil
depth, Tillage
operations.
|
5. Evaluation of data
needs and availability
Data required
to calculate the indicator
|
Period of existence
of a certain land use type.
|
Data sources
|
Necessary data
are easily available and accessible and the cost/benefit
ratio is reasonable.
|
Availability
of data from national and international sources
|
Data can be obtained
from various regional, national or international institutions
involved in collecting and elaborating such data.
|
6. Institutions that
have participated in developing the indicator
Main institutions
responsible
|
Agricultural University
of Athens, Greece
|
Other contributing
organizations
|
Universities of
Lisbon, Murcia, Basilicata, Amsterdam, Leeds
|
7. Additional information
Bibliography
|
Geeson, N., Brandt,
J., and Thornes, J., 2001. Mediterranean Desertification:
A mosaic of processes and responses. J. Wiley &
Sons, London, 439 p.
|
Other references
|
Kosmas, C., Danalatos,
N., Cammeraat, L.H., Chabart, M., Diamantopoulos,
J., Farand, R., Gutierrez, L., Jacob, A., Marques,
H., Martinez-Fernandez, J., Mizara, A., Moustakas,
N., Nicolau, J.M. Oliveros, C., Pinna, G., Puddu,
R., Puigdefabregas, J., Roxo, M., Simao, A., Stamou,
G., Tomasi, N., Usai, D., and Vacca, A., 1997. The
effect of land use on runoff and soil erosion rates
under Mediterranean conditions. Catena, 29:45-59.
|
Contacts Name
and address
|
Agricultural
University of Athens
Dr Constantinos Kosmas
email: lsos2kok@aua.gr
|
|