Soil erosion

UNL – Faculdade de Cięncias Sociais e Humanas
Departamento de Geografia e Planeamento Regional
Mestrado em Gestăo do Território – Detecçăo
Remota e Sistemas de Informaçăo Geográfica

Degradação de Ecossistemas Mediterrâneos

ANO LECTIVO 2010-2011
2° SEMESTRE

Soil erosion as a great example of environmental problem
in Portugal

Work Written by:

Filipe Oliveira Santos, nº 32124
Anna Złakowska, nº 32492, ERASMUS

Lisbon, May 29 - 2011

Soil erosion as a great example of environmental problem in Portugal

Introduction ................................................................................................................................ 3
To define Soils ........................................................................................................................... 4
Factors of soils formation by Dokuchajev .............................................................................. 4
Soils of Portugal ......................................................................................................................... 6
Figure. 1. Lithology of Portugal ................................................................................................. 7
Figure 3. Soil use of Portugal ................................................................................................... 10
Soil erosion processes .............................................................................................................. 11
Types of erosion ................................................................................................................... 11
Mação – Study Area ................................................................................................................. 13
How to avoid soil erosion......................................................................................................... 16
Conclusion ................................................................................................................................ 24
References ................................................................................................................................ 25

2


Introduction:

The threat of nuclear weapons and man's ability to destroy the environment are really
alarming. And yet there are other almost imperceptible changes - I am thinking of the
exhaustion of our natural resources, and especially of soil erosion - and these are
perhaps more dangerous still, because once we begin to feel their repercussions it will be too
late." (p144 of The Dalai Lama's Little Book of Inner Peace: 2002, Element Books, London)
(http://soilerosion.net/, accessed on 03.06.2011)

The objective of this project is soil erosion which is a big environmental problem of
the world, of Europe and of Mediterranean area. In spite of this major ecological problem,
there is no receive adequate media coverage like this in case with climate change and air
pollution. But people need to understand that much the same as air and water, soils constitutes
an element of system which keeps human alive. What is more, the greatest explanation of this
issue is written in quotation which is mentioned above.
Soil erosion is an unfavourable process that contributes to land degradation. Two
factors which are rainfalls and specific climate cause mostly soil erosion in Portugal. This is
a natural process but human activities increase this environmental problem. Therefore, there is
a need for finding new solutions and methods how to avoid soil erosion in the future.
This project include also tabular and cartographical form. The maps was made in
ArcGIS 10. It was made by cooperation two students from UNL in Lisbon and from UMK in
Toruń.

3


To define Soils:

The world “soil”, like many common words, has several definitions. Soil is a natural
component of environment which allow to grow the land plants. This meaning is still the
common understanding of the world. However, soil for pedologist means also something
different. They do not only consider soil as a part of visibly Earth surface but also this part
which human eye cannot see. Soil Taxonomy (an american soil classification) define it as
a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs
on the land surface, occupies space, and is characterized by one or both of the following:
horizons, or layers, that are distinguishable from the initial material as a result of additions,
losses, transfers, and transformations of energy and matter or the ability to support rooted
plants in a environment. (ftp://ftp-fc.sc.egov.usda.gov/NSSC/Soil_Taxonomy/tax.pdf
(10.05.2011)). Why soil is so important? The answer is simply. People consider soil important
because it supports plants that supply food, fibers, drugs, and other wants of human and
because it filters water and recycles wastes. Soil covers the earth’s surface as a continuum,
exception bare rock, or on the bare ice of glaciers.
(http://soils.usda.gov/education/facts/soil.html (10.05.2011))

Factors of soils formation by Dokuchajev:
About 1870, a new concept of soil was introduces by the Russian school led by
Dokuchajev who is known as a father of soils science. He introduced the idea that soil is not
something inert and stable, but it develops and evolves under the influence of factors of soils
formation: climate,living matter, earthy parent materials, relief and age of landforms. (ftp://ftp
fc.sc.egov.usda.gov/NSSC/Soil_Taxonomy/tax.pdf (10.05.2011)). Dokuchaev invented the
first equation of soil formation:
s = f(p, cl, o)t </dd>
where:
s = soil,
p = parent material,
cl = climate,
r = topography,
o = organisms.

4


In 1941, Hans Jenny redefined the equation and added a factor which is time.

s = f(p, cl, r, o, t, …) </dd>
where:
s = any soil property is a function of
p = parent material,
cl = external climate,
r = topography,
o = biotic potential,
t = time,

1. Parent material: the material from which the soil is formed. The parent material is the soil
that was present at the beginning of the new state factor assemblage. The influence of
parent material on soil properties is preponderant in young or relatively immature soils,
but it is progressively reduced by the influence of the other factors.
2. Climate: the meteorological conditions which surround the soil system (temperature,
rainfall, humidity, etc.), and is consistent with the concept of regional climate. The real
soil climate (pedoclimate) depends on both regional climate and unique features of the
soil, such as depth, color, texture, and its position on the landscape.
3. Topography: The topography of a site incorporates its relief (relative differences in
elevation), its aspect (position with respect to cardinal coordinates), and the general shape
of the land surface.
4. The biotic potential: It was defined by Jenny as the independent factor represented by
the biota of the system, namely the microbial, plant, and animal gene flux that enters the
system from the surroundings.
5. Time: All of the above factors assert themselves over time, often hundreds or thousands of
years. Soil profiles continually change from weakly developed to well developed over
time. (http://www.eoearth.org/article/Soil_forming_factors (10.05.2011))

5


Soils of Portugal:

Portugal is a country in the south Europe which has an access to Mediterranean
Sea. The territory of Portugal includes an area in the Iberian Peninsula and several
archipelagos in the Atlantic Ocean: the archipelagos of Madeira and the Azores.
Most of Portugal’s soils are arid, and sandy, though in the north the soil often is
rocky. Except for parts of northern Portugal that receive significant precipitation and along
the country’s primary rivers, which deposit fertile alluvium, the soils are not sustainable
for agricultural production. In the central and southern parts of the country, the soils are
generally poor and incapable of significant agricultural production without extensive
irrigation schemes. (www.britannica.com, 10.05.2011)
Currently there is no actual portuguese classification of Portugal. The last one was
written in 1974 by Cardoso. Since this time there is no actualization. Therefore, in the
table there is comparison old Cardoso’s classification and two international one: World
Reference Base for Soil Resources and Soil Taxonomy. To make a legend to map of soils
there was used European classification.
Tab.1. Soils of Portugal by Cardoso, WRB, USDA
(www.dha60anos.lnec.pt/pdf/workshop_11DEZ/Sessao%201/Casimiro%20Martins.pdf (11.05.2011)
Cardoso (1974) WRB (2006) USDA (2003)
Ordem Refrence Soil Group Ordem
Solos Incipientes Leptosols, Arenosols, Entisols, Inceptisols
(Litossolos, Regossolos, Fluvisols,
Aluviossolos, Coluviossolos) Cambisols
Solos Litólicos Cambisols Inceptisols
Solos Calcários Cambisols Inceptisols
Calcisols
Barros Vertisols Vertisols
Solos Mólicos Kastanozems Mollisols
Solos Argiluviados Luvisols, Lixisols Alfisols
pouco insaturados
Solos Argiluviados Alisols Ultisols
muito insaturados
Solos Podzolizados Podzols Entisols e Spodosols
Solos Halomórficos Fluvisols, Solonchaks Entisols (Aquents)
(Solonetz) Aridisols
Solos Gleysols e Planosols Entisols e Alfisols
Hidromórficos
Solos Histosols Histosols
Hidromórficos

6


Figure 1 . Lithology of Portugal. There are three major units of geomorphology, the Old Massif, which
occupies 70% of the country, Edgings the Sedimentary and Sedimentary Basins of the Tagus and
Sado(Adapted from Atlas digital do Ambiente, 2002).

7


Figure 2 - Soils of Portugal. Young soils, whose characteristics reflect poorly developed in some cases
predominantly bedrock, other relief or climate. (Adapted from Atlas digital do Ambiente, 2002)

8


Figure 3 – Land Use Capabilitty on Portugal. (Adapted from Atlas digital do Ambiente, 2002)

9


.

Figure 4 – Location of Study Area. – Mação is located on the district of Santarém, Central Sub-Region an
the Pinhal Interior Sul. The municipality is bordered to the northeast by the municipality of Proença-a-
Nova, east of Vila Velha de Ródão and Nisa, south by Hawk, on the southwest by Abrantes, at the western
Sardinia and Vila de Rei and northwest by Serta

10


Soil erosion processes:

If people would like to “fight” against soil erosion, they need to know an enemy. Then, it is
easier to find a solution and solve a problem.

Soil erosion is a natural process, occurring over geological time, and indeed it is a process
that is essential for soil formation in the first place. With respect to soil degradation, most
concerns about erosion are related to accelerated erosion, where the natural rate has been
significantly increased mostly by human activity.
(http://eusoils.jrc.ec.europa.eu/library/themes/erosion/, acessed on 10.05.2011)

Types of erosion:
Soils erosion is caused by natural environment as well as human activities. But a human
impact on soil erosion can be described as a form of accelerated erosion. Two components of natural
environment affect soil erosion and the names of them are wind and water.
a. Wind erosion
Soil erosion by wind may occur dry, sandy or dusty surfaces where there is poor
vegetation, are exposed to strong winds. Erosion involves the picking up and blowing away of
loose fine grained material within the soil. Damage from wind erosion is of numerous types.
The dust storms resulting there from are very disagreeable and the land is robbed of its long-
term productivity. Crop damage, particularly in the seedling stage, by blowing soil is often a
major concern. Serious stand and subsequent yield and quality losses are incurred and, in the
extreme, tender seedlings may be completely killed. Often, sufficient soil is removed to
expose the plant roots or ungerminated seed, and this results in complete crop failure.
Covering of established crops or pasturage by drifting soil is another common result. These
are but a few of the more evident results of wind erosion. The most serious and significant by
far, however, is the change in soil texture caused by wind erosion. Finer soil fractions (silt,
clay, and organic matter) are removed and carried away by the wind, leaving the coarser
fractions behind. This sorting action not only removes the most important material from the
standpoint of productivity and water retention, but leaves a more sandy, and thus a more
erodible, soil than the original.

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b. Water erosion
Both rainfall and runoff factors must be considered in assessing a
water erosion problem. The impact of raindrops on the soil surface can break down soil
aggregates and disperse the aggregate material. Lighter aggregate materials such as very
fine sand, silt, clay and organic matter can be easily removed by the raindrop splash and
runoff water; greater raindrop energy or runoff amounts might be required to move the
larger sand and gravel particles.
There are four types of water erosion: sheet erosion, rill erosion, gull erosion, tunnel
erosion.
(http://www.ideaconnection.com/solutions/5944-Soil-erosion-by-wind.html, 11.05.2011)

Tab. 2. Types of water erosion
(http://geografia.fcsh.unl.pt/lucinda/Leaflets/Leaflet%20B1%20EN.pdf, 03.06.2011)
Type of water erosion Definition
Splash erosion A movement of particle of soils which is caused by drops of rain.
Sheet erosion It happens when a thin layer of soil is removed by rainfall and
surface runoff ( the surface has to be sloping).
Rill erosion It occurs on sloping fields, mostly on recently cultivated soils
or roadside embankments. Water forms small channels of
only several decimetres in depth.
Gully erosion It is the removal of soil along drainage lines by surface water
runoff. In a short space of time, the soil may be lost to a
considerable depth and farmers are unable to work the land e
with ordinary farm equipment. Typically gulleys ranging
from 0.5m to as much as 25 to 30m.
Tunnel erosion occurs in soils that are prone to piping. These are often soils
that contain clay-rich layers that shrink and swell when
moistened or layers that have soils that disperse
spontaneously in water during rainfall.

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Mação – Study Area:

Desertification phenomenon affecting economic activities, social and environmental
concerns has increasingly been recognized by the scientific international community.

The United Nations Conference on Desertification (UNCOD) in 1977 adopted a Plan of
Action to Combat Desertification (PACD)( http://www.unccd.int/convention/menu.php ,
acessed on 03.06.2010). United Nations Convention to Combat Desertification has four
project areas in Portugal, with the Desire Program. We talk about Mação area in this work.
The main problem with Mação are the Forest Fires and the changes that we will describe.

In the beginning of the project were made initial contacts with land owners by IDARC
(Instituto de Desenvolvimento Agrário para ao Desenvolvimento da Região Centro) —

non-governmental organisation (NGO), wich represents the farmers and forest producers, By
Mação Municipality – Regional policy-maker.

In the course of research were being reinforced wills among the various stakeholders to
reverse the socio economic and environmental

Mação is in a zone of climatic transition: between the Atlantic and Mediterranean
climate. There are rainfall of around 600-1100mm annually. The soils are quite shallow and
stony Humic Cambisols.

It is a region that has suffered from drastic changes in the last decade. It has undergone a
period of about severe and prolonged drought.
The main risks to the quality of the soil, but stem from agricultural and forestry practices such
as crop from the top to the bottom of the slopes and frequent wildfires.

The effects are felt in particular by the catastrophic fires (2003 and 2005). There were
areas that came to fire twice in a short space of five years causing a severe degradation of soil
and vegetation. In addition, the local economy is weak, due to population aging, since Mação
is one of the municipalities that have the highest rate of aging of Portugal.

That is, the depopulation is also cause and effect of land degradation. Occurs in many
situations due to the fact that the land has become incapable of producing media for the
necessities of life of populations as a result of degradation to which humans subjected over
time, or the fact that the poverty of the land has not raised the necessary and proper interests
of both economic and social. But to give up, leave these areas to the neglect, lack the
conditions that allow the mitigation, so as to promote the regeneration of vegetation and consequently
the phenomena of water infiltration into the soil and subsoil.

13


Several national and international projects have been undertaken in order to try to
reverse degradation of these situations, either in socio-economic terms or in environmental
terms.
The program works DESIRE active until 2012 as a tool to go deeper into the
investigation of problems and processes of degradation and a desired classification of the
effectiveness of measures to try to reverse the degradation processes.
(http://www.desirehis.eu/index.php?option=com_content&view=article&id=39%3Ama-portugal-study-site-
description&catid=216%3Amacao-portugal&Itemid=365&lang=en, acessed on 03.06.2011).

Was established and developed a close working relationship over the past year
between the teams involved in the Portuguese proposal DESIRE and Portuguese UNCCD
focal point. Moreover, relations between the teams involved DESIRE the regional authorities
and the regional federation of farmers for development (IDARC) has existed for over a
decade and were built and reinforced with several previous studies and development of joint
projects since 1992. All institutions involved are willing to become members of the investors
and stakeholders in the area of Mação.
Due to the gloomy environmental context and socio-economic development, the
region of Macau has been an area of study since 1992 and has been covered with several
projects:
1. under the project IBERLIM (EV5V-0041) "Land management practice and limiting
erosion, in contrast to local fire and gullied Iberia" (1992-1994), in which the impacts
of forest fires have been evaluated.
2. MEDCHANGE Project (ERB-IC18-CT97-0147), "Effects of the use and land cover
change management practices of land degradation in forest and grassland ecosystems"
(1997-2000) and Project MEDAFOR (NV4-CT97-0686 ) "Consequences for the
mitigation of desertification of EU policies affecting forestry activity: an approach to
socio-economic and environmental physics combined" (1998-2001) allowed a deeper
understanding of degradation processes. The absence of a deep integration of end
users within the projects limits the transfer of knowledge from research level to the
operational level.
(Http://www.desire project.eu / index.php? Option = com_content & task = view & id = 17 & Itemid =
35 acessed on 06/03/2010).

14


3. Under the Project Climed (ICA3-2000-30005) "Effects of climate change and climate
variability on water availability and water management practices in Western
Mediterranean" (2001 - 2004), in which the risks of flooding and drought were
evaluated, with particular emphasis on the preparation of local communities to cope
with global changes.
All studies have led to the conclusion that:
a) local populations are very poorly prepared to face the challenges that global climate
change will put the management of natural resources and lack of credible alternatives.
b) Being in a transition area between the sub-humid and semi-arid climate, is a situation
that on what the studies so far fail in global perspectives able to compare a variety of
experiments in order to propose viable alternatives sustainable solutions.

Furthermore, the participatory dimension of DESIRE is expected to produce more
profound impact than previous projects, where the effective participation of actors and
stakeholders was not achieved.
The focal point of UNCCD in Portugal was part of the Directorate General of Forest
Resources "(Actual-AFN --National Forest Authority), which has played an important role in
the development of reforestation programs in the wake of the disasters of 2003 and 2005 fires
. The Municipality of Mação is responsible for managing the territory and its resources,
taking an active role in planning (eg. through the Technical Office of Forestry) and an action
on the municipality with regard to planning policies.
The CCDRC is the advice of the regional government with responsibility for environment
and planning, and responsibilities in the management of EU funds and government investment
in Regino center. The IDARC such as farmers' association with a leading position in the
development of agriculture plays an important role in demonstrating new techniques and
promote courses for Land Owners, Farmers and Agro Forestry Producers
(http://www.desirehis.eu/index.php?option=com_content&view=article&id=39%3Ama-portugal-study-site-
description&catid=216%3Amacao-portugal&Itemid=365&lang=en, acessed on 03.06.2011 ).

Recently, several political policies were designed and implemented to promote soil
conservation and improve the agriculture and forestry, national and European level. Several
project are being implemented recently, especially in order to reforest a portion of the burned
areas. The results of previous projects show a wide range of rates of soil erosion and the

15


amount of land for different land uses, land uses with some conservatives, such as Pinus
pinaster and Eucalyptus spp. plantations in terraces. All other land uses show soil losses at
least forty times higher, on average, and terrestrial fluxes are significantly higher. Among the
land uses with higher risk are those resulting directly or indirectly from human activities such
as plowing and fallow grove, or forest fires and sprout pine.

Catastrophic fires of 2003 and 2005 led to an increasing of the pressing need to change
this scenario. So, were proposed in 2003 a number of initiatives advocating major changes in
the way of how to do and mange forests. This initiatives had as main objective the promotion
of forest planning and its effective management, where none exists.
However, the implementation of this set of measures had strong socio-cultural constraints already
described. So to lead to a Sustainable Forest Management System trying to overcome these
constraints, trying to encourage partnerships between forest owners and taking advantage of
available financial measures to this end, we incorporated AFLOMAÇÃO, the January 22,
2004. The grouping of properties in management units in a patchwork of 80000 Municipality
agricultural and forestry lands, owned by almost 15.000 owners (50% of whom do not reside
in the Municipality), was essential ( http://www.aflomacao.pt/ on 03.06.2011).

Aflomação began operating on 2004. Were made efforts to implement the proposals approved
in 2003 by the Sustainable Forest Management System, dividing the entire Municipality in
management units. This Units were subsequently Formed ZIF´s created by the Forest
Intervention Decree Law 127/2005 of August 5, amended by Decree Law 15/2009 of 14
January. The main purpose is that the tens of thousands of small forest properties doomed to
abandonment by the exodus of owners and recurrence of fires, are aggregated into forest
management units of area not less than 1000 ha. The Aflomação, through their means and
technical capacity, management intends to support these ZIF effectively and professionally,
fostering development and forest management in the Municipality of Mação, helping by this
conduct the Desertification ( http://www.aflomacao.pt/ on 03.06.2011).

At national level the Council of Ministers Resolution No. 69/99, published in Official Gazette
No. 158, Series IB, from July 9 approved the National Programme of Action to Combat
Desertification (PANCD) by setting the procedures for its implementation.

16


The National Action Plan Against Desertification has the following objectives:
1. Conservation of soil and water;
2. Fixation of the active population in rural areas;
3. Restoration of affected areas;
4. Public awareness of the desertification problem;
5. Consideration of the fight against desertification in general and sectorial policies;

Some of the Specific Objectives:

“ Regional development, rural and local, as a determinant of population stability in the
regions most susceptible to desertification and drought, and reduction of human pressures on
the most densely populated areas;
Organization of the agents of economic and social development, about their professional
interests, economic, cultural, sports, environmental, as a way for active participation of people
in decisions that concern them and the value and classification of the territory;
Improved conditions for the exercise of agricultural activities compatible with the
characteristics of the natural support that are developed;
Extension and improvement of forest management and occupancy for strengthening the role
of forests in conserving soil and water;
Identification of the most affected areas and allocation of resources necessary for recovery of
degraded areas;
Policy management of water resources to ensure the necessary integration of territorial
management, linking appropriately the different uses of water and environmental protection
and conservation of natural resources.” (http://www.afn.min-agricultura.pt/portal/pancd on 03.06.2010)

This program was born as a result of the UN Convention, which also established the World
Day to Combat Desertification.
In 2002, the desertification affected more than one third of the the Portuguese continental
territory, particularly the Alentejo and Algarve. Since it began work, the committee focused
on four pilot areas (Arribas Douro, Pinhel interior south - Mação, described in this paper), left
bank of the Guadiana (Mértola area) and hills of the Algarve (Alcoutim and Castro Marim)
that deserved a more urgent need to combat desertification, understood as soil degradation,

17


land abandonment or lack of population.
(http://www.lpn.pt/LPNPortal/DesktopModules/SubPaginaProjectosDetalhes.aspx?ItemId=94&Mid=40&Paren
tId=8, on 03.06.2010).

Since late 2010, there are already proposals to the Centre National Desertification that
desertification through IDIC (Indicators DesertWatch) has conducted monitoring for changes
in the National Plans, with respect to to the regions of Lisbon and Tagus Valley, Alentejo and
Algarve .

18


Figure 5 - Type of Soils on Study Area (Adapted from Atlas digital do Ambiente, 2002).

19


Figure 6 – Precipitation on Study Area(Adapted from Atlas digital do Ambiente, 2002) .

20


Figure 7 - Forest Fires on 2003 and 2005 on StudyArea(Adapted from AFN , 2010).

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How to avoid soil erosion

Soil conservation is a very important issue, both in developing and developed nations
What is more, soil conservation is not only for farmers and agriculturists – it has a far-
reaching effect on the environment and so concerns all of us. There is a growing need to
prevent and control soil erosion and soil contamination, and to maintain soil fertility.
Implementing various soil conservation strategies and methods can help in stopping soil
erosion, in preserving the quality of the soil and in increasing its productive capacity. Good
soil conversation leads to enriched lands, better crop fields, good financial returns and
a balanced environment.
What are the proper erosion control methods that can be utilized and how will you
implement them?
A reply on this question is written below. There are some methods which can avoid
soil erosion in the future:
 Planting dense rows of trees as wind-breaks along the borders of the land, especially on
the sides that are exposed to stiff winds. Their roots stabilize the soil and prevent it from
being shifted away by the wind.
 Planting crops in rotation. Alternating crops helps avoid depleting the soil nutrients too
fast.
 Planting cover crops. These stabilize the soil and reduce the effects of soil erosion. They
also discourage the spread of weeds and help the soil retain its moisture in the summers.
 Ploughing along the contour of the land.
 Planting crops parallel to the slope of the land.
 Going for strip cropping. This involves planting grasses or pulses between regular crops
like maize. The maize crop is not particularly effective in preventing soil erosion, but the
grasses keep erosion in check.
 Adding mulch to the soil surface. This prevents erosion by acting as a barrier and catching
run-off water.
 Adding coir logs as barriers. These are very useful in areas where too much erosion has
taken place and act as erosion preventing barriers and a support for new developing
vegetation. Aside from coir barriers, sand bag and gravel bag barriers are also used.

22


 Growing grass on slopes and in waterways. Grassed waterways prevent too much soil
from being washed away.
 Making use of natural as well as man-made fertilizers.
 Keeping the land fallow in order to rest it.
 Managing the levels of salinity. In areas where irrigation is in excess or where the saline
water tables are low, the salinity levels can go up and make the land unsuitable for
agriculture. This problem can be resolved by the use of humic acid.
 Managing the soil pH. The soil pH is what determines the amount of nutrients that the
plants can absorb from the soil. Soil pH levels can be raised or decreased, as needed, by
adding certain chemicals – for example, agriculture lime for raising pH level and
ammonium phosphate for reducing it.
 Encouraging beneficial soil organisms like earthworms and nitrogen fixing bacteria to
thrive in the soil. The presence of such organisms enriches the soil.
 Using man-made chemical insecticides, pesticides and herbicides in very low amounts.
Over use of chemicals can poison the soil and kill of useful organisms, and is generally
harmful to the environment.
 Regularly add minerals to the soil. Minerals provide much-need nutrients to the soil to be
absorbed by the plants. To mineralize the soil, add chemical supplements or try adding
crushed rock.

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Conclusion:

Soil erosion leads to the phenomenon of land degradation . It is is caused by natural environment
as well as human activities.

The phenomenon of desertification is usually see as an environmental problem, but towards
the Convention to Combat Desertification (UNCCD), land degradation in climates with a
certain degree of dryness, resulting from natural factors or human activities. However,
conditions for Portugal, run alongside the two concepts, as we can see by the exemple of
Mação.

The desertification is cause and effect of land degradation. Occurs in many situations due to
the fact that the land has become incapable of producing media for the necessities of life of
populations as a result of degradation to which humans subjected over long time, or the fact
that the poverty of the land has not raised the necessary and proper of soicial and economic
interests. But giiving up, leave these areas to the neglect, lack the conditions that allow the
mitigation, so as to promote the regeneration of vegetation and consequently the phenomena
of water infiltration into the soil and subsoil.

It is what is happening in large areas in the country principalmente a sul do Mondego,
Alentejo e Algarve, where land had been taken to extremes of degradation and now are
abandoned and are highly degradative phenomena scenarios such as fires and floods. The
sharp depopulation that occurred makes today in terms of human presence is reduced to a very
small population and aging.

All theses facts discourages to apply measures in these areas, accentuating the trend towards
depopulation increasingly larger and more serious. But, like at Mação, were all institutions
involved are willing to become members of the investors and stakeholders , if more work and
investigation and rural extension work and promote forest investment sustainable are carried
out, it may think of reversing the situation.

24


References

 http://soilerosion.net/
Website accessed at: 03.06.2011

 ftp://ftp-fc.sc.egov.usda.gov/NSSC/Soil_Taxonomy/tax.pdf
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 http://www.eoearth.org/article/Soil_forming_factors
 www.britannica.com
 www.dha60anos.lnec.pt/pdf/workshop_11DEZ/Sessao%201/Casimiro%20Martins.pdf
 http://eusoils.jrc.ec.europa.eu/library/themes/erosion/
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portugal-study-site-description&catid=216%3Amacao-portugal&Itemid=365&lang=en,
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94&Mid=40&ParentId=8
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http://www.aflomacao.pt/

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