Environmental Engineering Reference
In-Depth Information
Fig. 17.1, above. For example, to name just a few
methods for drier parts of southern Europe, we need
to improve water-harvesting and -desalinization
techniques, evergreen and deciduous forest tree-
propagation and -establishment techniques, water-
shed revegetation, multi-purpose use of large and small
herbivores, and various post-fire soil-stabilization
measures, among others (Vallejo 1996, Vallejo &
Alloza 2003; see also Whisenant 1999). Generally
speaking, the issue of fine-tuning needs to be discussed
and negotiated among scientists, managers and other
stakeholders working together on an ecological
restoration or a CMR project, since the intervention
undertaken in this sense may alter the initial experi-
mental design!
Having identified and elaborated on some of the
problems that face ecological restoration as it pertains
to many, but not all, socio-economic and historic
situations in Europe, we shall now present a case study
that illustrates the questions and problems addressed
thus far in this chapter. In it, we wish especially to
raise the issue of the complex urban-rural interfaces,
mentioned at the outset of the chapter as being one
of the key challenges for ecological restoration in the
coming years. Far more than in the restoration of mires,
wetlands or forests far from human population nodes,
restoration actions in peri-urban and urban areas
cannot avoid a plethora of socio-economic, financial
and political issues - and conflicts - that must be con-
fronted even if they are entirely reconcilable.
ecosystems within the areas concerned. Indeed, these
peri-urban areas constitute an important nexus for eco-
logical restoration practice and science in the coming
years, and may in fact generate a large portion of the
social and political demands for ecological restoration
in developed countries. Ideally, ecological restoration
efforts should be planned in the context of the
re-integration, reconstruction or 're-weaving' of frag-
mented landscapes (Saunders
et al.
1993) and com-
munities, so as to provide a positive, constructive or
proactive socio-economic systems approach to the
actions undertaken.
In wildland areas near large urban areas that are
undergoing strong pressures for increased transport cor-
ridors and building, both conservation and restoration
are increasingly engaged and performed in the con-
text of so-called ecological compensation (van der
Meulen & Salman 1996), also sometimes called mitiga-
tion, for example in North America. In theory, this
process seeks to ensure the protection, improvement
or restoration of high-value ecosystems and landscapes,
within or in close proximity to peri-urban or protected
areas that are allocated to high-intensity, urban
utilization which is in most cases incompatible with
ecosystem or biodiversity conservation. Therefore,
where there is a strong demand on land for urban
development, a trade-off is often proposed between
land conservation and land occupation in nearby
areas. This is done in the perhaps naïve expectation
that given adequate study and planning, the two land
uses will be ecologically as well as economically
compatible. In many cases, these sorts of projects, if
successful, represent reclamation projects or habitat
enhancement rather than restoration
per se
. However,
there are exceptions, such as that described in Clewell
(1999).
17.4.2 Case study: the Llobregat river
delta, Barcelona, Spain
On the perimeters of growing towns and cities, the
worldwide phenomenon of urban expansion is gen-
erating a kind of ecological degradation, in the
urban-rural or urban-wildland interfaces where land
uses often undergo rapid transformations, including
abandonment of former agricultural uses and/or real-
location related to housing, commerce or transport.
Concurrently, of course, human population density
increases dramatically. CMR in those degraded lands
can include measures ranging from simple gardening
and landscaping criteria to be used more thoroughly
in land-use planning and, at the other extreme, rehab-
ilitation or full-scale restoration efforts for certain
The problem
The Llobregat river delta has been deeply affected by
centuries-old, intensive agricultural activity. Notably,
the coastal wetlands were almost entirely drained
during the 19th and early 20th centuries, and indus-
trial development has proceeded rapidly since the
1960s to the present day. However, by the early 20th
century it was recognized that dune stabilization
would be needed to protect nearby fields from
unwanted coastal sands. Dune fixation was thus
