Environmental Engineering Reference
In-Depth Information
recorded in northeastern Portugal between 1979 and 2002 (Pocas
et al.,
2011b). In
contrast, the landscape became coarser and unifunctional in Serra de Monchique
in southeast Portugal due to the total abandonment of rainfed agriculture and its
replacement by eucalyptus afforestation (Krohmer and Deil, 2003). In the Span-
ish Pyrenees, although land use changes expanded the plant cover and contributed
to a more natural landscape, they led towards simplification and homogenization
of the landscape with decreased fragmentation resulting in an increased fire risk
but decreased sediment transport to the lowlands (Lasanta-Martinez
et al.,
2005).
Homogenization of the landscape was also observed in the eastern Pyrenees after
1953, when mountain cropping and livestock grazing started to decrease in favour
of forests (Roura-Pasqual
et al.,
2005). A general homogenization of the landscape
was also detected in Italy between 1954 and 2000 due to forest recovery (Geri
et al.,
2010b); similar changes also took place in the White Mountains of Crete
(Papanastasis and Kazaklis, 1998) and the Pindos mountains of central Greece
(Chouvardas, 2001) due to land abandonment between 1945 and 1989. Interest-
ingly, a less diverse and simpler landscape was also found on the Psilorites moun-
tain of Crete, where land intensification (overgrazing) occurred between 1961 and
1989. This suggests that both extensification and intensification of land uses lead to
homogeneous landscapes.
Land use changes also impact on biodiversity, both species and habitat diversity.
Mediterranean mountains, whether in continental or island locations, are centres of
plant diversity and endemism. According to Medail and Quezel (1999), the rates
of plant species endemism exceed 20%. In addition, the same mountains are home
to several endangered animal species, such as the Iberian lynx (
Lynx pardina
)in
Spain and the Anatolian leopard (
Panthera pardus panthera
) in Turkey, as well as
several endemic species such as the mouflon (
Ovis orientalis
) in Sardinia, Corsica
and Cyprus, the Spanish ibex (
Capra pyrenaica
) (Regato and Salman, 2008) and the
agrimi (
Capra aegagrus cretensis
) in the mountains of Crete. All these species are
affected by land use changes. In general, land abandonment results in a decrease of
plant species richness and habitats, particularly when the woodland canopy closes
(MacDonald
et al.,
2000) while the mammals and bird species associated with
forests tend to increase (Falcucci
et al.,
2007). However, plant species richness in-
creases when livestock grazing and pastoral wildfires are extensified (Papanastasis
et al.,
2002). On the other hand, carbon sequestration is increased with abandon-
ment, especially when pastures are converted to woodlands (Padilla
et al.,
2010).
Finally, land use changes have an impact on soils and natural hazards. Expan-
sion of cultivated lands in forests and shrublands coupled with overgrazing of the
remaining rangelands results in significant soil loss and sediment yields through
erosion (Merzouk and Dhman, 1998; Puigdefabregas and Mendizabal, 1998). Land
abandonment, on the other hand, and the resulting colonization of old arable fields
by a dense shrub cover as well as afforestation can control both soil erosion and run-
off (Garcia-Ruiz
et al.,
1996; Garcia-Ruiz, 2010). However, if abandoned arable
lands, particularly those on terraces, are intensively grazed by livestock then ac-
celerated erosion may occur (Lasanta
et al.,
2011). Moreover, the expansion of
