Catálogo de publicaciones - libros

The paper discusses some basic concepts relative to desertification processes that support a more holistic approach to the problems faced in the country. A concept where land is seen as a territory and where land and water resources combine with human resources and opportunities for development is assumed. The identification of areas susceptible to desertification is described and the insufficiency of used indicators is discussed, mainly in relation to the climatic driving forces including droughts. Observations referring to vulnerability indicators show that the desertification processes affect large areas or territories where water resources are scarce, soil resources are often poor and non-agricultural vegetation is far from climax. Furthermore, natural resources seem do not respond anymore to the demand of the modern society particularly concerning agriculture. Thus, former equilibriums in land use and land condition are broken or tend to be disrupted while the population in these areas shows less capability to reverse the present situation. In areas susceptible to desertification, population density is very low and the respective growth rate is highly negative, aging is increasing with the dependency on aged people, illiteracy is above average, and the purchasing power of population is much lower than average. A desertification cycle and issues to reverse the situation are discussed. These include the need for the society to understand that policies to combat desertification shall focus the populations with priority over the environment in order to re-establish or create new equilibriums. The need for public participation, innovation on local political functioning, regionalization, development of public awareness, and education are also discussed.

The total arable land in Turkey is 28.054.000 ha. However, the prime soils cover only 17.5% of the total land surface and the productivity of the remaining soils is mainly limited by topography, depleted organic matter and high clay contents.

Climatic variation and human activities are major factors resulting in land degradation in arid and semiarid lands. In the Mediterranean region and over history, climatic drying was coincidental with developing agricultural technology and the rapid increase of the population and their dependence on the grain field, timber, and animal products. As a result of human population demand, it is evident that depletion of natural resources, such as water (surface or ground) and soil (e.g., soil erosion) and reduction of farm productivity, leads many farmers to move to alternative lands or to urban areas. This has a major impact on socioeconomics resulting in a decrease of per-capita food production affecting the political stability of the region and enhancing poverty.

Among factors causing soil degradation one of the most important, although less studied in Mediterranean environments, is the irreversible loss of soil due to urbanisation processes, inserted into the more general concept of soil sealing. In coastal Mediterranean regions, such as the Valencia Region, Spain, land cover transformations are mainly produced by contemporary socio-economic changes that have produced a drift from traditional agriculture to industrial and tourism economies, reinforced by population’s trends to concentrate in cities or larger urban regions. Evaluation of soil sealing is then a key element to understand soil degradation and the disappearance, in most cases, of highly productive soils.

This contribution proposes an integrated approach to detect and quantify land-use and land-cover changes as a basis for studying and predicting changes in environmental processes leading to desertification. The approach has been applied in Tabernas (Almería, Southeast Spain), a representative area of the Mediterranean region where a combination of extreme environmental conditions and modifications of the land-use pattern that occurred in the last decades have led to increase the risk of desertification.

Until the early seventies land degradation and desertification were not considered a major issue in most Mediterranean regions. Traditional agricultural systems were believed to be able to keep those processes in check. Thus low priority was assigned to research programmes and projects on soil erosion and conservation, preference being given to the impact of farm machinery on soil structure and compaction along with the role of organic matter in the soil.

Environmental changes, increasing scarcity of natural resources or rising opportunities for rent-seeking behaviour, can play a decisive role in the emergence of conflicts – namely by accelerating or triggering social problems. Environmental stress rarely leads directly to conflict, but may cause tension in already marginalized areas. Land degradation and desertification with its implication for food security is commonly recognized as one such stress factor. As an added complication migration of affected people into cities or onto even more marginal land increases poverty and has the potential of causing social unrest and ethnic tension.

Land degradation and desertification represents one of the most striking sets of processes affecting the Mediterranean Region causing persistent deterioration of the physical, chemical and biological properties of the land components, especially the soil. Land degradation, then, results in loss of overall , which in turn impairs sustainable development. This is particularly evident in the Southern Mediterranean, with entire landscapes no longer able to maintain their productive functions.

The distinctive character of Mediterranean areas arises from both physiographic conditions and the history of human development. The aridity, the frequency of drought events, the management of natural resources, especially soil, water and vegetation cover and the human pressure on fragile ecosystems, have produced land degradation, water shortage and. Finally, high risk of desertification, all issues increased by the effects of the climatic change. On the other hand, the already existing food security problems, especially in South Mediterranean countries, can be increased because of these issues.In this work we make a description of desertification processes in the Mediterranean area and we relate them to food security issues since we consider they are closely connected. Differences between North and South Mediterranean approaches to desertification and food security are marked and a special focus on causes for food insecurity is presented. Poverty, especially rural poverty, is considered the main driving force for food insecurity and possible solutions are discussed. Aspects like small farming, land tenure, local markets, trade aspects and water issues are considered relevant. Support to small farmers and local markets is considered essential to assure food security and to stop desertification processes. Finally, reforms on land and trade policies are considered necessaries.

The relationship between grazing intensity and ecosystem performance is complex and can depend on the prevailing ecological conditions. Previous studies have revealed that,in traditional grazing ecosystems, grazing can reduce ecosystem diversity in poor soils, butincrease diversity and productivity in rich ecosystems subject to moderate grazing pressure. We are interested in detecting long-term structural changes or drift in an ecosystem before itis too late to prevent irreversible degradation. We analyzed vegetation spatial patterns andcomplexities of four Mediterranean communities: Tihmadit Region (Middle Atlas, Morocco),Camiyayla (Namrum) Region (Taurus Mountain, Turkey), Sykia Region (south of theSithonia Peninsula, Greece), and Cabo de Gata Nijar Natural Park, Spain. Grazingdisturbance was most intense near shelter and water points, which lead to gradients in soilsurface disruption, compaction, and changes in the composition and cover of perennialvegetation. Dense matorral was more resistant to species loss than were moderately denseand scattered matorral, and grassland. Information fractal dimension decreased as we movedfrom a dense matorral to a discontinuous matorral, and increased as we moved to a morescattered matorral and to a grassland, which resulted in two opposing processes (interactiondeclining with ecosystem development, and immigration increasing with degradation) in acommon pattern, i.e., small patches homogeneously distributed in the landscape. Characteristic species of the natural vegetation declined in frequency and organization inresponse to higher grazing disturbance, while species of disturbed areas exhibited theopposite trend. Overall, the spatial organization of the characteristic plants of each community decreased with increasing vegetation degradation, with the intensity of the trend being related to the species' sensitivity to grazing. Developmental instability analyses of key species were used to determine the sensitivity of dominant key species to grazing pressure. Palatable species, which are better adapted to being eaten, such as Periploca laevigata, Phillyrea latifolia and Genista pseudopilosa, were able to resist moderate grazing pressure, while species of disturbed, grazed sites did not change developmental instability in response to increasing grazing pressure, such as Thymus hyemalis, Teucrium lusitanicum and Cistus monspeliensis. The usefulness of these monitoring tools in preventing land degradation is discussed.