John Libbey Eurotext

Science et changements planétaires / Sécheresse

Tree-grass interactions in the south-western Iberian Peninsula dehesas and montados Volume 17, issue 1, Janvier-Juin 2006

Authors
Centre d’écologie fonctionnelle et évolutive (Cefe), Équipe « Dynamique réactionnelle des écosystèmes, analyse spatiale et modélisation » (DREAM), Centre national de la recherche scientifique (CNRS), 1919, route de Mende, 34293 Montpellier cedex 5 France
  • Key words: parkland, agroforestry, sylvopastoralism, Spain, Portugal
  • Page(s) : 340-2
  • Published in: 2006

The dehesas and montados of the south-western Iberian Peninsula are man-made ecosystems characterized by a savanna-like physiognomy. The open tree stratum is dominated by three Mediterranean oak species, Quercus ilex, Q. suber, and Q. pyrenaica, whose densities range from 10 to 80 trees per hectare. In this paper, the key processes involved in the functioning of the dehesas are discussed, with particular reference paid to the significant modifications of environmental conditions induced by the presence of isolated trees. We describe how, in the face of the physiological constraints imposed by climatic stress, the changes in soil properties caused by the presence of trees increase the availability and uptake of soil water and permit a more efficient use of the limited water resource by the two life forms of vegetation: grass and trees.