Editor's note 10Sep12: Source D711-8.1 To be reviewed when D20 and D213  are available. Eleni - the text of this category introduction cannot be edited from the front end. You need to copy and paste into a word document, make the corrections using track changes and email it to Jane.

Land and ecosystem degradation and desertification (LEDD) are complex socio-environmental phenomena resulting from the interactions between biophysical and socio-economic factors operating at different spatial and temporal scales. These coupled socio-ecological systems (SES) possess positive and negative feedback mechanisms that give rise to nonlinear relationships and to drastic transitions to irreversible degradation states. LEDDRA defines human responses to LEDD as any type of action taken in LEDD-affected regions with the purpose either of directly and explicitly tackling a LEDD problem or of addressing other socio-economic problems. Positive responses to LEDD aim at solving problems associated with LEDD and at preserving the socio-ecological resilience of affected regions.

Grazing lands are the result of human decisions to increase food production and they are socio-ecological systems that dominate less productive and inaccessible areas. They constitute one of the largest land uses in the world occupying about one-quarter of the world's total land area while one fifth of the world's arable land is used for growing cereals for livestock feed (FAO (1996). The vegetation of grazing land is adapted to herbivores and requires the activity of livestock to maintain the productivity of grasslands and the integrity of these socio-ecological systems. In addition, recent studies have shown that it is not only important to maintain the livestock pressure but also that the spatial distribution of grazing pressure is more important than total grazing pressure, which has only a limited influence on degradation (Okayasu et al. 2010). Therefore, systematic management of the spatial distribution of animals is essential to prevent land degradation and desertification in extensively grazed rangelands. Mobile pastoralism provides one way to respond to variations in intra- and inter-annual climatic fluctuations and prevent overgrazing.

Traditional land use has important consequences for the conservation of grazing land, where extensive grazing and transhumance practices are important and enable such landscapes to be maintained (Di Pietro 2001). These semi-natural landscapes have great cultural interest because they maintain a large pool of biodiversity. Nowadays, such landscapes are under pressure from a range of different interests: agriculture, forestry, tourism and nature protection (Fischer 1990). Balancing these sometimes competing demands with natural processes, such as succession, is not always easy. Different components of the system interact direct or indirectly. For example, changes in population size and characteristics influence energy demand, economic and socio-political changes indirectly affect grazing land, and so on. In addition, the response of a socio-ecological system is not uniform and it depends on the initial conditions and the broader socio-economic circumstances. Thus, population increase may lead to overgrazing in some areas or to land abandonment in others. Population increase in south Mediterranean countries leads to over-exploitation of rangelands and desertification, while in northern Mediterranean countries, migration to cities and intensification of agriculture have led to land abandonment. Thus, the way that land use and climate change influence grazing lands depends not only on the climatic conditions but also on the economic development of the region in question. In the last few decades, rural tourism has increased significantly, with the associated development of tourist infrastructures and reduction of farmlands. New developments, mass tourism, urbanization and over-exploitation of water resources lead to a progressive decline in traditional husbandry. Economic activity is nowadays centered around the services sector, with special emphasis on recreation and tourism.

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