Land use and land cover change after agricultural abandonment - The case of a Mediterranean Mountain Area (Catalan Pre-Pyrenees)

摘要

Land cover mapping obtained from photointerpretation of aerial photographs and orthophotographs was used to quantify land cover changes between 1957 and 1996 in a Mediterranean middle mountain area. Expansion of forested area is clearly the main land cover change caused by the abandonment of traditional agricultural activities and by the use of other materials and energy sources instead of forest resources. As a result, about 64% of the area was covered by forest by 1996, whereas in 1957 forests accounted for only 40% of the land cover. Spontaneous afforestation of abandoned fields with Scots pine (Pinus sylvestris L.) in terraced areas and areas of sparse scrub vegetation, coupled with an increase in the density of forest canopies, has been responsible for this expansion of woodland. The influence of physiographic factors in land cover change processes in the terraced areas of the catchment was also considered. The results demonstrate that within the terraced areas, north-facing and more elevated steeper slopes are more intensely afforested. However, an accurate analysis of the role played by these factors in land cover change cannot be carried out because the pattern of land abandonment is not independent of these physiographic characteristics. Furthermore, field observations at the terrace scale are evidence of the relevant influence of local topography in afforestation dynamics.