Paysages dynamiques et conservateurs? Couvert ve'ge'tal actuel et changements de l'occupation du sol dans la Serra de Monchique (Portugal) Dynamic and conservative landscapes? Present vegetation cover and land-use changes in the Serra de Monchique (Portug
Krohmer, Julia; Deil, Ulrich
In the Serra de Monchique, a small mountain ridge in the hinterland of the Algarve, land-use trends and vegetation changes have been studied in a diachronic analysis. The main question was whether the landscape evolution in all parts of this Mediterranean mountain area is parallel or if there are divergent trends at a finer regional scale, triggered by physical site factors and/or socio-economic patterns. For that purpose, seven perimeters throughout the Serra were selected, representing the ecoregions as well as the discrepancies in accessibility, infrastructure and social conditions. The changes during the last thirty years have been analyzed by mapping the land-use and vegetation in 1996 and by a retrospective interpretation of air photographs from 1966. The general trends are the total abandonment of rainfed agriculture and of the traditional shifting cultivation system on slopes, and their replacement by Eucalyptus afforestations respectively by Cistus-heathland or Arbutus-maquis, originating from spontaneous recolonisation. The modernisation results in a coarser landscape structure and in unifunctional and more rectangular land-use units. Beside these common tendencies, the changements are variable at a regional scale, in intensity as well as in direction. We find quite dynamic regions like the big valleys Odeluca and Seixe and a conservative area like the northern slope of the Picota mountain: There the plant cover is still very fine structured and traditional land-use patterns are persistent. The tendencies can be parallel or divergent (intensification in the valley bottom by irrigated Citrus orchards, extensification by pasturing on fallow land). More than the physical conditions, the socio-economic factors are the driving forces. The contrast between the modernized coastal plains and a marginalized hinterland goes on in the mountainous area itself.