Soil erosion


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Soil erosion

  1. 1. 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° SEMESTRESoil 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
  2. 2. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalIntroduction ................................................................................................................................ 3To define Soils ........................................................................................................................... 4 Factors of soils formation by Dokuchajev .............................................................................. 4Soils of Portugal ......................................................................................................................... 6Figure. 1. Lithology of Portugal ................................................................................................. 7Figure 3. Soil use of Portugal ................................................................................................... 10Soil erosion processes .............................................................................................................. 11 Types of erosion ................................................................................................................... 11Mação – Study Area ................................................................................................................. 13How to avoid soil erosion......................................................................................................... 16Conclusion ................................................................................................................................ 24References ................................................................................................................................ 25 2
  3. 3. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalIntroduction:The threat of nuclear weapons and mans ability to destroy the environment are reallyalarming. And yet there are other almost imperceptible changes - I am thinking of theexhaustion of our natural resources, and especially of soil erosion - and these areperhaps more dangerous still, because once we begin to feel their repercussions it will be toolate." (p144 of The Dalai Lamas Little Book of Inner Peace: 2002, Element Books, London) (, accessed on 03.06.2011) The objective of this project is soil erosion which is a big environmental problem ofthe 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 airpollution. But people need to understand that much the same as air and water, soils constitutesan element of system which keeps human alive. What is more, the greatest explanation of thisissue is written in quotation which is mentioned above. Soil erosion is an unfavourable process that contributes to land degradation. Twofactors which are rainfalls and specific climate cause mostly soil erosion in Portugal. This isa natural process but human activities increase this environmental problem. Therefore, there isa 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 inArcGIS 10. It was made by cooperation two students from UNL in Lisbon and from UMK inToruń. 3
  4. 4. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalTo define Soils: The world “soil”, like many common words, has several definitions. Soil is a naturalcomponent of environment which allow to grow the land plants. This meaning is still thecommon understanding of the world. However, soil for pedologist means also somethingdifferent. They do not only consider soil as a part of visibly Earth surface but also this partwhich human eye cannot see. Soil Taxonomy (an american soil classification) define it asa natural body comprised of solids (minerals and organic matter), liquid, and gases that occurson 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 rootedplants in a environment. ( Why soil is so important? The answer is simply. People consider soil importantbecause it supports plants that supply food, fibers, drugs, and other wants of human andbecause 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.( (10.05.2011))Factors of soils formation by Dokuchajev: About 1870, a new concept of soil was introduces by the Russian school led byDokuchajev who is known as a father of soils science. He introduced the idea that soil is notsomething inert and stable, but it develops and evolves under the influence of factors of soilsformation: climate,living matter, earthy parent materials, relief and age of landforms. ( (10.05.2011)). Dokuchaev invented thefirst equation of soil formation: s = f(p, cl, o)t </dd>where:s = soil,p = parent material,cl = climate,r = topography,o = organisms. 4
  5. 5. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalIn 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 ofp = 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. ( (10.05.2011)) 5
  6. 6. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalSoils of Portugal: Portugal is a country in the south Europe which has an access to MediterraneanSea. The territory of Portugal includes an area in the Iberian Peninsula and severalarchipelagos 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 isrocky. Except for parts of northern Portugal that receive significant precipitation and alongthe country’s primary rivers, which deposit fertile alluvium, the soils are not sustainablefor agricultural production. In the central and southern parts of the country, the soils aregenerally poor and incapable of significant agricultural production without extensiveirrigation schemes. (, 10.05.2011) Currently there is no actual portuguese classification of Portugal. The last one waswritten in 1974 by Cardoso. Since this time there is no actualization. Therefore, in thetable there is comparison old Cardoso’s classification and two international one: WorldReference Base for Soil Resources and Soil Taxonomy. To make a legend to map of soilsthere was used European classification.Tab.1. Soils of Portugal by Cardoso, WRB, USDA( (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
  7. 7. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 1 . Lithology of Portugal. There are three major units of geomorphology, the Old Massif, whichoccupies 70% of the country, Edgings the Sedimentary and Sedimentary Basins of the Tagus andSado(Adapted from Atlas digital do Ambiente, 2002). 7
  8. 8. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 2 - Soils of Portugal. Young soils, whose characteristics reflect poorly developed in some casespredominantly bedrock, other relief or climate. (Adapted from Atlas digital do Ambiente, 2002) 8
  9. 9. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 3 – Land Use Capabilitty on Portugal. (Adapted from Atlas digital do Ambiente, 2002) 9
  10. 10. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugal .Figure 4 – Location of Study Area. – Mação is located on the district of Santarém, Central Sub-Region anthe 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 westernSardinia and Vila de Rei and northwest by Serta 10
  11. 11. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalSoil erosion processes:If people would like to “fight” against soil erosion, they need to know an enemy. Then, it iseasier to find a solution and solve a problem.Soil erosion is a natural process, occurring over geological time, and indeed it is a processthat is essential for soil formation in the first place. With respect to soil degradation, mostconcerns about erosion are related to accelerated erosion, where the natural rate has beensignificantly increased mostly by human activity. (, acessed on 10.05.2011)Types of erosion: Soils erosion is caused by natural environment as well as human activities. But a humanimpact on soil erosion can be described as a form of accelerated erosion. Two components of naturalenvironment 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 poorvegetation, are exposed to strong winds. Erosion involves the picking up and blowing away ofloose 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 amajor concern. Serious stand and subsequent yield and quality losses are incurred and, in theextreme, tender seedlings may be completely killed. Often, sufficient soil is removed toexpose 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. Theseare but a few of the more evident results of wind erosion. The most serious and significant byfar, 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 coarserfractions behind. This sorting action not only removes the most important material from thestandpoint of productivity and water retention, but leaves a more sandy, and thus a moreerodible, soil than the original. 11
  12. 12. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugalb. Water erosion Both rainfall and runoff factors must be considered in assessing awater erosion problem. The impact of raindrops on the soil surface can break down soilaggregates and disperse the aggregate material. Lighter aggregate materials such as veryfine sand, silt, clay and organic matter can be easily removed by the raindrop splash andrunoff water; greater raindrop energy or runoff amounts might be required to move thelarger sand and gravel particles.There are four types of water erosion: sheet erosion, rill erosion, gull erosion, tunnelerosion.(, 11.05.2011)Tab. 2. Types of water erosion(, 03.06.2011)Type of water erosion DefinitionSplash 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. 12
  13. 13. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalMação – Study Area: Desertification phenomenon affecting economic activities, social and environmentalconcerns has increasingly been recognized by the scientific international community.The United Nations Conference on Desertification (UNCOD) in 1977 adopted a Plan ofAction to Combat Desertification (PACD)( ,acessed on 03.06.2010). United Nations Convention to Combat Desertification has fourproject 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, ByMação Municipality – Regional policy-maker.In the course of research were being reinforced wills among the various stakeholders toreverse the socio economic and environmental Mação is in a zone of climatic transition: between the Atlantic and Mediterraneanclimate. There are rainfall of around 600-1100mm annually. The soils are quite shallow andstony Humic Cambisols.It is a region that has suffered from drastic changes in the last decade. It has undergone aperiod of about severe and prolonged drought.The main risks to the quality of the soil, but stem from agricultural and forestry practices suchas 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 wereareas that came to fire twice in a short space of five years causing a severe degradation of soiland vegetation. In addition, the local economy is weak, due to population aging, since Maçãois 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 manysituations due to the fact that the land has become incapable of producing media for thenecessities of life of populations as a result of degradation to which humans subjected overtime, or the fact that the poverty of the land has not raised the necessary and proper interestsof both economic and social. But to give up, leave these areas to the neglect, lack theconditions that allow the mitigation, so as to promote the regeneration of vegetation and consequentlythe phenomena of water infiltration into the soil and subsoil. 13
  14. 14. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugal Several national and international projects have been undertaken in order to try toreverse degradation of these situations, either in socio-economic terms or in environmentalterms. The program works DESIRE active until 2012 as a tool to go deeper into theinvestigation of problems and processes of degradation and a desired classification of theeffectiveness of measures to try to reverse the degradation processes.(, acessed on 03.06.2011). Was established and developed a close working relationship over the past yearbetween the teams involved in the Portuguese proposal DESIRE and Portuguese UNCCDfocal point. Moreover, relations between the teams involved DESIRE the regional authoritiesand the regional federation of farmers for development (IDARC) has existed for over adecade and were built and reinforced with several previous studies and development of jointprojects since 1992. All institutions involved are willing to become members of the investorsand stakeholders in the area of Mação. Due to the gloomy environmental context and socio-economic development, theregion of Macau has been an area of study since 1992 and has been covered with severalprojects: 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 / index.php? Option = com_content & task = view & id = 17 & Itemid = 35 acessed on 06/03/2010). 14
  15. 15. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugal 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 moreprofound impact than previous projects, where the effective participation of actors andstakeholders was not achieved. The focal point of UNCCD in Portugal was part of the Directorate General of ForestResources "(Actual-AFN --National Forest Authority), which has played an important role inthe 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 actionon the municipality with regard to planning policies.The CCDRC is the advice of the regional government with responsibility for environmentand planning, and responsibilities in the management of EU funds and government investmentin Regino center. The IDARC such as farmers association with a leading position in thedevelopment of agriculture plays an important role in demonstrating new techniques andpromote courses for Land Owners, Farmers and Agro Forestry Producers(, acessed on 03.06.2011 ). Recently, several political policies were designed and implemented to promote soilconservation and improve the agriculture and forestry, national and European level. Severalproject are being implemented recently, especially in order to reforest a portion of the burnedareas. The results of previous projects show a wide range of rates of soil erosion and the 15
  16. 16. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugalamount of land for different land uses, land uses with some conservatives, such as Pinuspinaster and Eucalyptus spp. plantations in terraces. All other land uses show soil losses atleast forty times higher, on average, and terrestrial fluxes are significantly higher. Among theland uses with higher risk are those resulting directly or indirectly from human activities suchas 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 changethis scenario. So, were proposed in 2003 a number of initiatives advocating major changes inthe way of how to do and mange forests. This initiatives had as main objective the promotionof forest planning and its effective management, where none exists.However, the implementation of this set of measures had strong socio-cultural constraints alreadydescribed. So to lead to a Sustainable Forest Management System trying to overcome theseconstraints, trying to encourage partnerships between forest owners and taking advantage ofavailable financial measures to this end, we incorporated AFLOMAÇÃO, the January 22,2004. The grouping of properties in management units in a patchwork of 80000 Municipalityagricultural and forestry lands, owned by almost 15.000 owners (50% of whom do not residein the Municipality), was essential ( on 03.06.2011).Aflomação began operating on 2004. Were made efforts to implement the proposals approvedin 2003 by the Sustainable Forest Management System, dividing the entire Municipality inmanagement units. This Units were subsequently Formed ZIF´s created by the ForestIntervention Decree Law 127/2005 of August 5, amended by Decree Law 15/2009 of 14January. The main purpose is that the tens of thousands of small forest properties doomed toabandonment by the exodus of owners and recurrence of fires, are aggregated into forestmanagement units of area not less than 1000 ha. The Aflomação, through their means andtechnical capacity, management intends to support these ZIF effectively and professionally,fostering development and forest management in the Municipality of Mação, helping by thisconduct the Desertification ( on 03.06.2011).At national level the Council of Ministers Resolution No. 69/99, published in Official GazetteNo. 158, Series IB, from July 9 approved the National Programme of Action to CombatDesertification (PANCD) by setting the procedures for its implementation. 16
  17. 17. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalThe 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 theregions most susceptible to desertification and drought, and reduction of human pressures onthe most densely populated areas;Organization of the agents of economic and social development, about their professionalinterests, economic, cultural, sports, environmental, as a way for active participation of peoplein decisions that concern them and the value and classification of the territory;Improved conditions for the exercise of agricultural activities compatible with thecharacteristics of the natural support that are developed;Extension and improvement of forest management and occupancy for strengthening the roleof forests in conserving soil and water;Identification of the most affected areas and allocation of resources necessary for recovery ofdegraded areas;Policy management of water resources to ensure the necessary integration of territorialmanagement, linking appropriately the different uses of water and environmental protectionand conservation of natural resources.” ( on 03.06.2010)This program was born as a result of the UN Convention, which also established the WorldDay to Combat Desertification.In 2002, the desertification affected more than one third of the the Portuguese continentalterritory, particularly the Alentejo and Algarve. Since it began work, the committee focusedon four pilot areas (Arribas Douro, Pinhel interior south - Mação, described in this paper), leftbank 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
  18. 18. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugalland abandonment or lack of population.(, on 03.06.2010).Since late 2010, there are already proposals to the Centre National Desertification thatdesertification through IDIC (Indicators DesertWatch) has conducted monitoring for changesin the National Plans, with respect to to the regions of Lisbon and Tagus Valley, Alentejo andAlgarve . 18
  19. 19. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 5 - Type of Soils on Study Area (Adapted from Atlas digital do Ambiente, 2002). 19
  20. 20. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 6 – Precipitation on Study Area(Adapted from Atlas digital do Ambiente, 2002) . 20
  21. 21. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalFigure 7 - Forest Fires on 2003 and 2005 on StudyArea(Adapted from AFN , 2010). 21
  22. 22. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalHow to avoid soil erosion Soil conservation is a very important issue, both in developing and developed nationsWhat 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 toprevent and control soil erosion and soil contamination, and to maintain soil fertility.Implementing various soil conservation strategies and methods can help in stopping soilerosion, in preserving the quality of the soil and in increasing its productive capacity. Goodsoil conversation leads to enriched lands, better crop fields, good financial returns anda 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 avoidsoil 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
  23. 23. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in Portugal 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. 23
  24. 24. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalConclusion:Soil erosion leads to the phenomenon of land degradation . It is is caused by natural environmentas well as human activities.The phenomenon of desertification is usually see as an environmental problem, but towardsthe Convention to Combat Desertification (UNCCD), land degradation in climates with acertain 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 ofMação.The desertification is cause and effect of land degradation. Occurs in many situations due tothe fact that the land has become incapable of producing media for the necessities of life ofpopulations as a result of degradation to which humans subjected over long time, or the factthat the poverty of the land has not raised the necessary and proper of soicial and economicinterests. But giiving up, leave these areas to the neglect, lack the conditions that allow themitigation, so as to promote the regeneration of vegetation and consequently the phenomenaof 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 areabandoned and are highly degradative phenomena scenarios such as fires and floods. Thesharp depopulation that occurred makes today in terms of human presence is reduced to a verysmall population and aging.All theses facts discourages to apply measures in these areas, accentuating the trend towardsdepopulation increasingly larger and more serious. But, like at Mação, were all institutionsinvolved are willing to become members of the investors and stakeholders , if more work andinvestigation and rural extension work and promote forest investment sustainable are carriedout, it may think of reversing the situation. 24
  25. 25. Degradação de Ecossistemas Mediterrâneos Soil erosion as a great example of environmental problem in PortugalReferences Website accessed at: 03.06.2011 Website accessed at: 10.05.2011 Website accessed at: 10.05.2011 Website accessed at: 10.05.2011 Website accessed at: 10.05.2011 Website accessed at: 10.05.2011 Website accessed at: 11.05.2011 Website accessed at: 10.05.2011, Website accessed at: 11.05.2011, Website accessed at: 03.06.2011 portugal-study-site-description&catid=216%3Amacao-portugal&Itemid=365&lang=en, Website accessed at: 03.06.2011 Website accessed at: 03.06.2010 94&Mid=40&ParentId=8 Website accessed at: 03.06.2010 Website accessed at: 03.06.2010 25
  26. 26. Degradação de Ecossistemas MediterrâneosSoil erosion as a great example of environmental problem in Portugal 26