Environmental Engineering Reference
In-Depth Information
Box 17.1 Food for thought
17.3.1 Reference areas: pros and problems
Restoration should be guided by scientific knowledge
(restoration ecology principles) and accommodate
social demands. As social demands are very variable
in time and space, a precautionary principle would
suggest that restoration actions (and especially large-
scale and long-term management, conservation and
land-use plans) should maximize the diversity of
future management options or ecosystem uses, for
example by avoiding transformations leading to
pathways of no return. In other words, it is prudent
to avoid irreversible processes that would require
future huge investments of energy to restore the site
or system if needs or priorities change at a later
date. Introducing the repair cost in the business plan
before initiating profound land transformations, in
whatever significant units (e.g. energy, non-renewable
resources, community impact indices or money),
provides good perspectives; some mining companies
are already progressing in this direction. The cost of
the destruction or non-reversible transformation of
nature should also be valued and factored in. This
is the area of research and development known as
ecological economics, and large numbers of topics,
documents and websites exist for consultation, a
sample of which were cited in Chapter 16. The ap-
plication of the precautionary principle is progress-
ing nowadays in Europe; see for example the REACH
(Registration, Evaluation, Authorisation and Restriction
of Chemicals) proposal for a strategy on chemicals
policy, from its generic recognition in the Treaty on
the European Union (EC 1992c, article 130 R.2).
Aronson and Le Floc'h (1996a) and Aronson
et al.
(2002) have argued for the usefulness of establishing
references - areas, ecosystems, landscapes - or even
a collation of reference information from various
sources (see Clewell & Lea 1990, Aronson
et al.
1993a, 1995, Egan & Howell 2001, SER 2002). This
process or approach is useful, as we and others have
argued, even if it is not essential to ecological
restoration (see Pickett & Parker 1994, Janzen 1998,
2002). In many although not all situations there
exists an array of forms, phases or avatars in which
vegetation can be seen, most of which are rather
removed from a pristine, undisturbed state. Accord-
ingly, several types of
reference
and sources of
reference information (White & Walker 1997) can
be suitable for restoration projects, including the
restoration of long-standing and still-relevant socio-
economic systems, which can serve as a reference
or yardstick with which to evaluate and attempt to
repair damaged ecosystems today. But there are sev-
eral obstacles to finding a clear and straightforward
application. Firstly, in Europe, as in most parts of the
world today, we often only have vestiges, and frag-
mented landscapes or ecological systems that could
effectively serve as references for ecological restora-
tion. Secondly, in Europe, as elsewhere, the situation
is further complicated by the many layers of history
and culture which render the choice of references highly
arbitrary. Finally, as the reader will recall, in Chapter
16 we introduced the notion of emerging ecosystems,
a notion that effectively obliges us to consider the
whole issue of choice and use of reference areas in
a new light. Reconciliation is possible, but the con-
ceptual process involved is as complex as the notion
of socio-economic systems. To further complicate the
picture, truly cultural landscapes are prevalent, and
much valued by citizens in general and many eco-
logists in particular (Farina 2000, Naveh 2000).
Cultural landscapes can and often should provide the
best reference for actual restoration or rehabilitation
projects. Of course, the relative value and naturalness
of a cultural landscape depends a great deal on
present-day perception and may underestimate the
extent to which profound and perhaps irreversible
degradation processes were initiated in the past in order
to produce those cultural landscapes (see Box 17.1).
The first step for setting up a reference can be to
create some simple models, flow charts or other
graphics describing how things have become the way
they are in the study area, and delineating some of
the alternative states (or basins of attraction; see
Anand & Desrochers 2004) that have existed, or that
are possible for the systems in question (see Wyant
et al.
1995, Yates & Hobbs 1997). In Fig. 14.2 was
presented one example, showing some of the pos-
sible successional pathways (including post-fire trends)
in relation to above-ground biomass of mature woody
plant communities and plant species richness (in
100-m
2
plots) in eastern Spain. A much more detailed
example of this kind of exercise is given in Fig. 17.2.
