Environmental Engineering Reference
In-Depth Information
present or willing to take up farming. Another reason may be the multiple activities
of the rural households, members of which are also engaged in non-farm activi-
ties such as tourism. The EU support of agriculture with subsidies in the southern
European countries, although it provided a satisfactory income to the farmers, did
not stop farm abandonment in the mountains, apparently because this did not lead
to any structural improvements of agriculture (Kasimis and Papadopoulos, 2001).
8.5.2 Natural dynamics of land use changes
Although land use changes in the Mediterranean mountains are mainly caused by
socioeconomic changes, environmental factors are also involved. They include cli-
mate, geology and relief. This is because a change in land use often produces a
change in land cover that is directly affected by these factors. For example, aban-
doned land will be colonized by natural vegetation more rapidly under favourable
rather than unfavourable climatic conditions. Also, climate conditions may reflect
the types of vegetation that become established in the abandoned lands. According
to Torta (2004), a prolonged shrubland phase occurs in the afforestation process
after land abandonment in the northern Apennines, while in the western Alps this
phase is absent or limited due to wetter conditions. He further states that climate,
particularly the quantity and distribution of annual rainfall, plays a major role on
a regional scale in determining the time and pace of afforestation after abandon-
ment, while natural factors such as topography, geopedological conditions, slope
and aspect play roles on a local scale. Such factors accounted for 13% of the to-
tal variance of the
Abies pinsapo
forest structure on the mountains of Spain and
Morocco on opposite sides of the Strait of Gibraltar, while the contrasting land use
(Spain vs Morocco) accounted for 23% of the total variance (Linares
et al.,
2011).
The question that arises is whether plant or vegetation cover following the land
use changes adheres to a standard theoretical model of change. After reviewing
several studies on land use changes in Mediterranean countries, Mazzoleni
et al.
(2004b) concluded that the gradual reduction or disappearance of the original for-
est cover in the southern and eastern Mediterranean countries follows the model of
successional regression. In the northern Mediterranean areas, on the contrary, land
abandonment that triggers the increase of forest cover follows one of two models:
(i) the auto-succession model in the areas where evergreen shrublands are colo-
nized by pines, resulting in increased frequency and magnitude of wildfires; or (ii)
the progression model in abandoned open spaces, forest plantations and sclerophyl-
lous evergreen formations that leads to the original (pre-disturbance) forest cover
composed of deciduous plant species (Figure 8.6).
Although there is a secondary succession of vegetation in the Mediterranean
mountains following intensification of agriculture and livestock grazing or aban-
donment, this succession is not always linear. In the Psiloritis mountain of Crete, for
example, where there is intensive grazing by sheep and goats, pine forests may be
directly converted to phrygana (garrigues) without going through the maquis stage,
