Land use changes - Mediterranean Mountain Environments - page 163

crops decreased by 43.5% from 1979 to 2002 due to the loss of economic competi-
tiveness and the decline and ageing of the rural population (Pocas et al., 2011a).
Land abandonment and human-driven changes such as pine plantations have in-
creased the fire risk and the incidence of large and devastating wildfires. After
studying these wildfires in central and northern Portugal over a period of 13-15
years from 1990, Silva et al. (2011) concluded that fire has a determinant role in
land use changes of the studied area, as it favoured shrubland persistency and the
conversion of other land use types to shrublands and forests.
8.4.3 Spain
Spanish Mediterranean mountains have become a marginal territory since the 1950s
when the rural population started to emigrate to the big cities in the lowlands result-
ing in farmland abandonment and loss of livestock farmers. In the Camero Viejo of
northwestern Spain, Lasanta et al. (2011) have found that the cultivated area was
reduced by 99% between 1956 and 1995, with the abandoned fields representing
99.4% of the cultivated area and 40.4% of the entire study area. The terrace walls
collapsed in 1995 leading to severe soil erosion. Also, the number of sheep fell
dramatically by 1995, and they were largely replaced by free-grazing cattle of im-
ported breeds that tend to overgraze the abandoned fields resulting in significant
soil erosion. Finally, the human population declined by 86.2%.
In the Spanish Central Pyrenees, the most significant land use changes since the
1950s have been the decline of sheep and the expansion of cattle breeding; the re-
duction of the cultivated area; the decline of cereal production in favour of pasture;
and the reforestation of many abandoned hill slopes (Garcia-Ruiz et al., 1996). In
addition to reforestation, the abandoned lands were also invaded by spontaneous
forest vegetation. Reduction of the farming area occurred simultaneously with pop-
ulation decline (Lasanta-Martinez et al., 2005). Also in the Central Pre-Pyrenees,
an expansion of the forested area was recorded between 1957 and 1996. This was
caused by spontaneous afforestation of abandoned fields and an increase of the
canopy density of the existing forests (Poyatos et al., 2003). The same processes,
namely the expansion of the forest area and the increasing canopy density of forests
already present in 1957, occurred also in the National Park of the Pyrenees (Gracia
et al., 2011). Ameztegni et al. (2010) found that land use change played a more
important role than climate in the increase of forest cover.
A new land use in the central Spanish Pyrenees is tourism, and especially skiing.
However, the area influenced by the ski resorts is restricted to nearby municipali-
ties, which show positive demographic changes and a continuation of the primary
activities (Lasanta et al., 2007).
In southeast Spain, with its drier climate, cropland abandonment resulted in an
increase of alfa ( Stipa tenacissima, or 'esparto') grasslands while shrublands de-
creased because of the extensive pine afforestation programme that was initiated in
1996 (Bonet et al., 2004). A reduction of the area covered by dehesa woodlands