Environmental Engineering Reference
In-Depth Information
8.4 Recent land use changes
8.4.1 Morocco
The reduction of forest cover has been the most important land use change in
Moroccan mountains over the last few years. Rejdali (2004) reports that Morocco is
losing an estimated 30 000 ha/year of forest cover due to the high demand for forest
products by an increasing rural population, the expansion of ploughing to create
more arable lands and the uncontrolled and intensive grazing by livestock, which
are forced to graze in more confined areas following the intensive cultivation. In the
central High Atlas mountains, in particular, forests were reduced by 20.7% between
1976 and 1996 resulting in a significant increase of the erosion potential (Merzouk
and Dhman, 1998).
There has also been a significant change in the traditional agricultural system
in the Moroccan mountains. In the past, this system was based on sedentary com-
munities, which depended on two complementary and integrated land use types:
intensive cropping on irrigated terraces and livestock husbandry, mainly sheep and
goats. Since the 1970s this equilibrium has been broken due to the very rapid pop-
ulation growth, which has put great pressure on the land leading to degradation of
the natural vegetation (Bencherifa, 1983). In addition, the traditional pastoral no-
madic migrations have ceased and the permanently settled people are engaged in
new agricultural activities (Bencherifa and Johnson, 1991).
8.4.2 Portugal
Recent land use changes in the Portuguese mountains were initiated in the 1960s
and were largely dictated by the gradual emigration of the rural inhabitants, mainly
the active generation, to the urban centres and the subsequent reduction of agri-
cultural activity. In a diachronic study of land use changes between 1947 and
1990 carried out in the Sierra de Malcata of central east Portugal, Cohelho-Silva
et al. (2004) found that the area covered by permanent crops such as olive groves
had diminished; the area of temporary crops such as cereals reached a maximum
in 1958 but thereafter started to decrease; and shrublands and forests had in-
creased since 1958. At the same time, the resident human population decreased
by 50% and farm animals declined in numbers by 54%. Similar results were also
recorded in the Sierra de Monchique of southern Portugal, where a diachronic
study of land use changes between 1966 and 1996 showed a total abandonment
of rainfed agriculture on slopes and its replacement with matorral (Krohmer and
Deil, 2003).
In northern Portugal, forest plantations created a new land use type. In the Na-
tional Park of Alvao, for example, pine plantations were established in the 1950s
at the expense of rangelands, thereby significantly altering the landscape (Timoteo
et al., 2004). By contrast, in a mountain landscape of northeast Portugal, annual
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