PART . VI Desertification Indicators and Forecasting Techniques ENVIRONMENTALLY SENSITIVE AREAS AND INDICATORS OF DESERTIFICATION

Desertification is the consequence of a series of important processes in the Mediterranean environments, especially in semi-arid and arid regions, where water is the main limiting factor of land use performance on ecosystems. Among the most important processes of desertification are soil erosion and salinization particularly affecting hilly areas and lowlands, respectively. Various methodologies have been developed in identifying and mapping environmentally sensitive areas (ESAs) to desertification. Studies have shown that the various types of ESAs have different behavior on crop production, plant growth, grazing capacity, and soil erosion rates. For example, olive oil and cereal production decreased as the type of ESA changes from non-threatened to critical areas. Soil erosion measures have shown that soil erosion rates increased as the sensitivity of land to desertification increased. Loss in land productivity greatly affects farmer’s income and measures applied for protecting the land from further degradation and desertification. The necessity of elaborating indicators is one of the priorities identified by the United Nations Convention to Combat Desertification (UNCCD). The use of indicators can generally simplify complex processes and provide appropriate tools for combating desertification. Indicators can be classified to those related a) to the physical environment (soil, vegetation, climate), b) to the land management (tillage operations, irrigation practices, animal density grazing the land, forest fire protection, erosion measures, etc), and c) to the socio-economic characteristics (farmer age, family size, farm size, subsidies, farmer income, etc). Indicators can be better used for defining land desertification risk if they are classified according to the land use type. For example important indicators for defining desertification risk for vineyards are related to land management as well as to land characteristics such as tillage operations, tillage direction, slope gradient, parent material, plant cover, etc. Studies, conducted in areas in which the main process of desertification was salinization, showed that important indicators for defining desertification risk were ground water depth, drainage, water quality, frequency of flooding, distance from the seashore, type of land use, rainfall, etc.