Environmental Engineering Reference
In-Depth Information
Table 11.1
Framework for the restoration of Mediterranean ecosystems. Drivers for restoration are identifi ed, as well as
actions that can be undertaken to attenuate them, and available techniques to implement these actions. Each driver must be
offset to ensure successful restoration.
Driver
Action
Technique
Persistent anthropogenic
disturbances, unwanted
species
Release disturbance
Limited access to people, herbivores, etc.
Fire prevention, windbreaks
Species control (fi re, herbicides, clearing)
Low propagule availability
Artifi cial introduction
Seeding, planting
Promote dispersion
Bird-mediated restoration, frugivory-mediated restoration
(artifi cial perches, catches and habitat amelioration)
Adverse environmental
conditions
Reduce soil losses
Emergency seeding, mulching, sediment traps
Ameliorate soil
properties
Amendments, nutrient immobilization, mulching,
drainage, soil preparation
Improve microclimate
Shelters, mulching, microsite selection
in the Old World, the great and continuous density of
historical layers in the Mediterranean Basin renders
diffi cult the selection and use of a precise historical
reference system
, such as is frequently sought in New
World settings (Egan & Howell 2001). References for
ecological restoration are usually taken from pre-
disturbance ecosystem information, in the case of
recently disturbed ecosystems (e.g. due to fi res), and
from historical information or from reference ecosys-
tems supposed to be natural, remaining in well-
preserved sites. Sustainable seminatural ecosystems of
socio-economic and cultural interest may well be taken
as references for restoration projects, especially in areas
like the Mediterranean region and highly transformed
parts of the other four MCRs. In this case, as always,
goals must be clearly defi ned in relation to site-specifi c
constraints and opportunities. A good example is the
dehesa
or
montado
woodlands in Spain, Portugal and the
rest of western Mediterranean Basin, which are artifi -
cially opened and managed savanna-like landscapes
designed and maintained for silvopastoral or agrosilvo-
pastoral uses (Aronson
et al
. 2009). In other MCRs,
landscapes and disturbance regimes existing before the
European settlements in the sixteenth-nineteenth cen-
turies very often guide restoration actions.
Despite the wide range of MCR restoration objec-
tives, some features are common to all MCRs:
1.
Soil and water conservation is generally the main
priority, for reducing and preventing soil losses and for
regulating water and nutrient fl uxes (Cortina & Vallejo
1999 ).
2.
Increasing ecosystem resilience to disturbances,
and ensuring the sustainability of restored lands by
promoting the re-assemblage of plant, animal and
microbial communities resilient to current and future
disturbance regimes.
3.
Improving landscape quality, from a local, cultural
perspective, and the provision of ecosystem services
(Figure 11.1 ).
4.
Promoting biodiversity, fostering the reintroduction
of key native species, while eradicating alien invasive
species, and battling their re - establishment.
11.2.2
Early post-fi re rehabilitation
In some cases, quick action is urgently needed before a
degradation process reaches or exceeds a certain thres-
hold beyond which restoration becomes prohibitively
expensive or impossible. This may be the case in some fi re-
sensitive systems, where wildfi re removes vegetation
cover, leaving an unprotected soil. In eastern Spain, for
example, many plant communities dominated by obligate
seeders (species unable to resprout after fi re), growing
preferentially on soft bedrocks and, especially, on equator-
facing slopes, commonly show slow post-fi re
recovery
(Pausas
et al
. 1999) and thus high
erosion
and
runoff
risk. Early post-fi re restoration can either be integrated in
an ecological restoration programme, or just concentrate
in short-term non-ecological objectives (e.g. plantations
for timber production). Emergency action after wildfi res
has been practised in California for nearly a century, pri-
marily to mitigate fl ooding and erosion. Federally man-
dated and fi nanced post - fi re activities in California, and
throughout the United States, was formalized in 1974
through the Burned Area Emergency Rehabilitation
