Restoration of Mediterranean woodlands - Restoration Ecology - page 194

Secondly, the contrast between the northern and
southern banks of the Mare Nostrum is striking
and stark: ever-growing agricultural abandonment
and rural exodus in southern Europe contrast like
night and day with north Africa and the eastern
shores of the Mediterranean, where land-use intensi-
fication and an unabated population increase in
coastal and inland areas alike create a very different
scene (Etienne et al. 1998, Blondel & Aronson 1999).

Like the other four Mediterranean-climate regions
(MCRs) in the world, the Mediterranean Basin's clim-
ate combines cool or cold and wet winters, and long,
hot and dry summers. Summer drought is of variable
duration, but frequent periods of drought can occur
at any time of the year (Vallejo et al. 1999). Water is
the key limiting factor (Noy-Meir 1973) for plant and
animal growth, and for human societies. There is also
a strong overall gradient of aridity in the Mediter-
ranean, from the north-west to the south-east. As mean
annual precipitation declines, the coefficient of vari-
ation of annual rainfall increases (Le Houérou 1984).
Furthermore, the basin is unusual among MCRs: it
is the only one of the five belonging to the Old World,
where human beings have for 10 millennia been living,
consuming resources and transforming natural land-
scapes and ecosystems to their own ends. Thus, here
alone among the MCRs, many plants and animals have
had ample time to adapt to the human presence; those
that did not adapt have, for the most part, disappeared.
Thus it is comprehensible, here perhaps more than
anywhere else, to speak of humans co-evolving with
landscapes (Naveh 1990) rather than appearing as mere
'parasites' of the biosphere (Odum 1996).
As elsewhere in the Old World, the great and con-
tinuous density of historical layers in the Mediter-
ranean region renders difficult the selection and use
of a precise historical reference system, such as is fre-
quently sought in New World settings (Egan & Howell
2001). This feature, which is shared with much of
Europe, contrasts sharply with other continents, and
has major consequences for restorationists, conserva-
tionists and ecosystem and land managers. The long-
standing alteration by humans (see section 14.1.2) has
lead to transformation and, often, irreversible degrada-
tion of natural ecosystems.
The combination of the great diversity of physical
conditions - for example topography, geology, soils
and the large number of possible pathways and
stages of succession (Fig. 14.2) occurring after vari-
ous disturbances as abandonment, fire or logging -
imparts to Mediterranean landscapes a particular
kaleidoscopic or patchwork pattern. The alternative
steady states and successional pathways found in
Mediterranean landscapes require that a choice be made
by restorationists and land managers depending on their
objectives.

14.1.1 Mediterranean particularities

The Mediterranean is one of the world's 18 biolog-
ical 'hot spots' (Myers et al. 2000), where exceptional
concentrations of biodiversity occur, and where much
of that biodiversity is in danger of depletion or
extinction. The region is home to over 25,000 species
of vascular plants, whereas only 6000 plant species
occur in Europe outside the Mediterranean Basin
despite its being an area three to four times greater
in size. Approximately 247 tree-like woody species
(capable of reaching at least 2 m in height) occur
in the canopies of the Mediterranean forests and
woodlands, whereas only 135 tree species occur in all
of non-Mediterranean Europe (Quézel et al. 1999).
Compared to northern and central Europe, unusually
high species richness is also found among Mediter-
ranean insects, mammals, birds and other groups of
animals, fully matching the botanical richness refer-
red to above. There is also an extraordinary richness
of wild relatives, ancient varieties and landraces of a
huge variety of domesticated plants and small live-
stock (Zohary & Hopf 1993).
The climate, geology and biogeography of the
region have contributed to the unusually high biodi-
versity of the Mediterranean; both it and the adjoin-
ing Near East have long been a perhaps unparalleled
nexus of exchange and interaction among contrasted
biotas and cultures - among European, south-west
Asian and African flora, fauna and human societies.
But there is an important historical element as well.
The Mediterranean Basin's very high spatial hetero-
geneity is still today amply mirrored, or reflected, by
linguistic, legislative, cultural and agricultural divers-
ity, especially in the various Mediterranean mountain
regions (McNeil 1992).