Agro-silvo-pastoral systems are widespread in the Mediterranean and can also be found in other areas of the world showing similar climatic conditions. In the southern and western part of the Iberian Peninsula these landuse systems, existing since many centuries, are commonly formed by open evergreen oak woodland, covering approximately 3 million hectars. These are the MONTADOS and DEHESAS of Portugal and Spain, which traditionally are exploited by multiple landuse including livestock breeding, forestry and cultivation. The importance of these areas rests on both environmental as well as socio-economic values.
However, these areas have undergone rapid change during the second half of the 20th century, from traditional farming systems with very low energy inputs from outside, to more simplified systems giving rise to decreasing diversity of land use and management techniques. Land degradation is recognized to constitute a problem in many of the dehesas and montados, including a lack of regeneration of the trees which threaten the future of the woodlands, soil erosion and degradation and increased runoff production.
A common feature is the coexistence of extensification and intensification, causing different problems of degradation. For example, headage payments produced a growth in animal numbers increasing the risk of soil and pasture degradation. On the other hand abandonment of livestock breeding produces vegetation change and leads to shrub encroachment and increased risk of wildfires.