Environmental Engineering Reference
In-Depth Information
are all more or less 'perturbation-dependent' (see Vogl
1980), and for which special treatment is required
(Naveh 1991, Farina 2000), we are concerned with
conservation, management for sustainable use and -
where necessary - restoration of damaged, degraded
or destroyed ecosystems.
Furthermore, we focus on restoration of vegetation,
and especially of large woody species, and leave the
restoration and re-introduction of animals aside in our
discussion. Large, woody plants and trees are the main
structural component in the Mediterranean Basin,
and in other MCRs, and they play an important, indeed
vital, role in the functioning of these ecosystems.
The annual occurrence of a long, dry season at the
hottest time of the year imposes a severe constraint
on all plant life (Joffre & Rambal 1993), and the pres-
ence of a tree or trees greatly modifies microclimate
and biological conditions both above and below the
ground. Further, in all areas long modified by humans,
trees and large shrubs can play an important role -
as bio-indicators - in forest and vegetation history,
and should also be used for determining the best
options, goals and procedures for ecological conser-
vation and restoration (Aronson et al. 2002). Thus,
we proceed from the notion that large, woody plants
provide a fundamental framework for natural and for
historical cultural or semi-cultural Mediterranean eco-
systems, and that therefore they must not be under-
estimated in the present context.
In line with the most recent definition of eco-
logical restoration (SER 2002; www.ser.org), the
basic objectives of restoration actions in the Med-
iterranean Basin are, or should be as follows.
120
Oak forest
100
80
Pine woodland
60
Ulex shrubland
40
Garrigue
20
Sward
0
0
5
10
15
20
25
30
Species richness (in 100 m 2 )
Fig. 14.2 Some of the possible successional pathways
(including post-fire autosuccessional trends) in relation
to above-ground biomass of mature communities
(Mg ha −1 ) and species richness (in 100 m 2 ) in eastern
Spain (very simplified). The various stages (alternative
steady states) are dominated by Quercus ilex ssp.
ballota (Oak forest), Pinus halepensis (Pine woodland),
Ulex parviflorus ( Ulex shrubland), Brachypodium
retusum (Sward) and Quercus coccifera (Garrigue).
Variability in biomass and richness within each
successional stage is not indicated, but can be large.
Grey lines represent slow or rare pathways.
14.1.2 A combined approach: restoration,
conservation and sustainability
Our general approach to restoring Mediterranean eco-
systems is based on the need to repair, rehabilitate and
restore ecosystem health and ecosystem services,
while also assuring greater attention to the inter-
related environmental and economic issues of biodiver-
sity on the one hand and sustainability science on the
other. This approach can be defended on purely eco-
nomic grounds (Balmford et al. 2002), but also finds
ample justification on social, cultural and ecological
grounds as well. Given the ancient history of human
use and transformation, the restoration of Med-
iterranean ecosystems necessarily follows a functional
and landscape-oriented approach (Hobbs 2002).
Furthermore, given that we are concerned with an array
of cultural, semi-natural and natural landscapes that
• To stop degradation, especially desertification pro-
cesses affecting the most sensitive Mediterranean
ecosystems.
• To promote improved ecosystem and landscape
function and structure, taking into consideration that
both groups of attributes do not relate in simple or
unique ways (e.g. Fig. 14.2).
• To assist secondary succession through stimulating
natural regeneration, by
1 making use of recognized succession trajectories
(Fig. 14.2), that offer a referential multi-attribute
system of potential restoration trajectories in
terms of improving structure and function;
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