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Status of Desertification in the Mediterranean Region


Assessment of the status of Mediterranean desertification requires a robust and agreed upon definition of desertification, which is still lacking, partly due to the widespread use of 'desertification' either interchangeably or in conjunction with 'land degradation'. By definition desertification is a subset of land degradation confined to drylands, thus adding 'land degradation' to 'desertification' implies relevance of the UNCCD to land degradation in both drylands and non-drylands, globally and in the Mediterranean. Another interpretation for pairing 'desertification' and 'land degradation' is that desertification is not a globally spatial but a dryland temporal subset of land degradation; namely 'desertification' represents culmination of the process of land degradation in the drylands. The UNCCD usage of 'desertification' (to be combated) in conjunction with drought (to be mitigated) and climatic variations (a desertification driver) also confounds understanding and assessment of desertification and its status. Qualifying desertification as a persistent reduction of biological productivity in the drylands may resolve difficulties in addressing desertification, though no agreement exists as to what degree of degradation and its reversibility properties would qualify as desertification. Desertification is habitually believed to be driven by human impact proportional to population size and growth rate, which are higher than the global average and relative to all other ecosystems, respectively. Global scale data demonstrating that desertification is highest at the intermediate section of the aridity gradient suggest that desertification is driven by an interaction of ecosystem sensitivity (expressed by natural biological productivity) and the pressure exerted on land resources (expressed by population density). Yet, though GDP and infant mortality rates are lower and higher in drylands, relatively to other ecosystems and to global averages, respectively, it is not known if the drylands' low human well-being is driven by desertification, or by the inherently low productivity of drylands impacted by growing populations, or both. Thus desertification constitutes a paradigm, one of a downward spiral of degradation leading to human misery, through self-reinforcing positive feedback loops. This paradigm is reinforced by an environmental security narrative, in which migrations and conflicts driven by the desertification-associated demand and supply-induced environmental scarcities, reduce overall environmental security in the drylands. A 'counter paradigm' based on some evidence suggests that drylands' adversities trigger 'induced innovations' in rural communities that lead to development tracks which circumvent desertification. Yet, if dryland population continues to increase the 'induced ingenuity' will eventually be exhausted, unless dryland livelihoods independent of land productivity are gradually adopted. Mediterranean climates, of wet winters but dry summers, prevail in five seaboard semiarid and dry-subhumid regions on the globe, one of which is the Mediterranean Basin, with a long history of intensive use by man resulting in biological adaptations providing high ecosystem resilience to human impact. The southern, African lands of the Mediterranean Basin are drier than the northern, European lands, the latter being mainly semiarid drylands, with high desertification extent, yet more people are affected by desertification in the southern than in the northern sections of the Basin. All over the Mediterranean Basin the most extensively used land is also the most intensively used and becoming most degraded, irrespective of type of use. Thus in the northern Mediterranean desertification is driven by irrigation developments, themselves driven by markets and regional agricultural policies, whereas in the southern Mediterranean desertification is driven by encroachment of cultivation on rangelands, which are driven by population growth and national policies. Yet, the Mediterranean ecosystems are fairly resilient to mounting external pressures, due to a balance in the interaction of soil state with soil vegetation cover, up to a point in which a threshold is crossed. A way to avoid desertification in grazed Mediterranean shrublands is to encourage the historical prevalence of a spatio-temporal mosaic of distinct patches of annual and perennial vegetation through controlling grazing and fire at moderate levels, and moving these controls adaptively and dynamically between patches. Yet, when degradation did take over, rehabilitation through afforestation have taken place on a large scale in the Mediterranean Basin. This afforestation, mainly with Aleppo Pine, reduced soil erosion and flooding but compromised water resources and poorly performed in restoring the indigenous vegetation cover, but seemed to be more successful and water-efficient in drier areas, where the objective was soil conservation rather than the vegetation restoration. Global climate change is projected to exert an additional pressure on the Mediterranean drylands, through an overall decrease in water resources, such that even a relatively small climatic change would suffice to initiate a spatio-temporal transformation of the Mediterranean semiarid to arid drylands, and also an overall transformation of non-drylands into drylands, in both their climate and their biological productivity. Given the projected combined impacts of global climate change, dryland population growth and the pressure on drylands brought about by global decline in good cultivable land, it may be effective to address Mediterranean desertification as an environmental security issue, which encompasses risking food security, health security, livelihood security, national and transboundary security. However, the direct links between desertification and migration within the Mediterranean Basin have not yet been demonstrated. Even though means to promote land productivity improve, an eventual widespread desertification leading to reduced human well-being, land desertion and migration can emerge in the Mediterranean Basin. A way out is to explore means of diversifying dryland livelihoods, such that the pressure on land resources is reduced yet dryland people opt to stay on their land. Paradoxically, with all its drawbacks, global climate change provides opportunities to people of the Mediterranean drylands, encouraging them to diversify their livelihoods, e.g. afforestation in the non-desert Mediterranean drylands for carbon trading, and solar energy development in the desert drylands for exporting electricity. These and other livelihoods of advantage in drylands yet not depending on dryland land resources can be mixed with improvements of traditional dryland livelihoods. Thus the flows between the southern and northern Mediterranean may dramatically transform - rather than development aid cash, payments for purchases of clean energy would flow from the North to the South, and the South-North flow of migrants would be replaced by North-South,flow of tourists. These changes would promote the sustainability of dryland livelihoods especially in the South, and would bring abut environmental security and subsequent political stability throughout the Mediterranean Basin.......

【作者名称】: Uriel N. Safriel
【作者单位】: The Hebrew University of Jerusalem, Jerusalem, Israel
【关 键 词】: Status of Desertification in the Mediterranean Region
【会议名称】: NATO advanced research workshop on water scarcity, land degradation and desertification in the mediterranean region : Environmental and security linkages; 20071210-11; Valencia(ES)
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 101,618,790
【摘要长度】: 7,326
【会议地点】: Valencia(ES)
【会议组织】: The Hebrew University of Jerusalem, Jerusalem, Israel;
【会议时间】: 2007
【上篇论文】: 外文会议 - Evaluation of Changes in the Tidal Regime of the Ems-Dollard and Lower Weser Estuaries by Mathematical Modelling
【下篇论文】: 外文会议 - Using Artificial Neural Network (ANN) to Explore the Influences of Number of Inventors, Average Age of Patents, and Age of Patenting Activities on Patent Performance and Corporate Performance

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