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The degradation of permanent semi-natural vegetation and the resulting acceleration of soil degradation and erosion processes constitute major elements of land degradation in the Mediterranean basin. These elements are triggered by human activities rather than climatic conditions. The Greek island of Crete represents a characteristic case of land degradation resulting from hundreds of years of intensive grazing and fires. Since Greece joined the European Communities in 1981, grazing in mountainous regions has greatly increased due to subsidies that became available through the Common Agricultural Policy. Within a European Research Project on the use of satellite remote sensing for monitoring environmental change in Mediterranean ecosystems (DeMon-2: An Integrated Approach to Assess and Monitor Desertification Processes in the Mediterranean Basin), we have initiated a study to monitor the impact of increased grazing pressure on two mountainous ecosystems in Crete. The approach is based on describing surface conditions and vegetation cover over time with a long-term series of earth observation satellites. (C)1998 Academic Press Limited.