Gerardo Moreno Marcos, Dpto. de Biología Vegetal, Ecología y Ciencias de la Tierra, Faculty of Sciences, University of Extremadura
Richard Dodd, Professor, Division of Ecosystem Sciences, Department of Environmental Science, Policy, and Management,University of California, Berkeley
Tree-covered rangelands are widespread in the Mediterranean but are also found in other areas of the world having similar climatic conditions. In the southern and western part of the Iberian Peninsula large areas are occupied by open oak woodlands which have evolved through centuries of multiple land use and are referred to as the montados and dehesas of Portugal and Spain. Comparable agrosilvopastoral systems exist also in Greece, Italy and the southern Mediterranean. The importance of these areas rests on both environmental as well as socio-economic values. They support outstanding diversity of wildlife, form unique landscapes, are the source of high-quality food derived from animal production, sustain rural population, and constitute an important basis for the growing demand of rural leisure and tourism. In California they are represented by the oak woodland ranches and occupy more than two million hectares and similar landscapes also exist in Chile and Australia.
In Europe these areas have undergone rapid changes during the second half of the 20th century, shifting from traditional farming systems with very low external energy inputs to more simplified systems causing decreasing diversity of land use and inadequate management techniques. Land degradation is recognized as a significant problem in many of these rangelands, including the lack of tree regeneration, which threatens the future of the woodlands as well as soil erosion, soil degradation and increased runoff production. A common feature is the coexistence of extensification and intensification, causing different problems of degradation. For example, subsidies in the form of headage payments in the EU led to an unchecked increase in animal numbers, thus increasing the risk of soil and pasture degradation. On the other hand, abandonment of livestock breeding produces vegetation changes, leading to shrub encroachment and an increased risk of wildfires.
The main focus of this session is to bring together researchers from different disciplines who have worked in these tree-covered rangelands with Mediterranean type climate. The complexity of these very diverse systems and the necessity of achieving knowledge useful for sustainable management call for integrated research. The session welcomes contributions dealing with the degradation and conservation of these ecosystems, including vegetation, soils, water and landscapes as well as economic, social and management aspects. Especially welcome are those studies applying an integrated approach. Included is research dedicated to the development of indicators for evaluating its state of conservation