Environmental Engineering Reference
In-Depth Information
human individuals and societies. Popular wisdom
around the world, and the common sense that comes
with age and maturity, both tell us that a person's
greatest and most abiding wealth is in fact his or
her
health
. From the preceding discussion however,
it should be clear that restoration ecology must be
concerned with both the integrity and the health of
ecosystems.
is that of ecological models or references, and from
where they are taken or constructed. For complex adap-
tive ecosystems there is no fundamentally right state
or community. But for both scientific and socio-
cultural-economic reasons, some states or better still
trajectories are certainly preferable to others, especially
with regard to socio-ecological systems.
16.2.7 Socio-ecological systems and their
relevance to the setting of objectives
and references
16.2.6 Emerging ecosystems
The concept of emerging ecosystems - as explained
in Milton (2003) and Lugo and Helmer (2004) - deals
primarily with land units partially or totally transformed
by people for agricultural, commercial or industrial use
that have an uncertain, and above all unprecedented,
ecological and socio-economic trajectory. Indeed,
'ecosystems that develop after changing social, econ-
omic and cultural conditions, so change the envir-
onment that new biotic assemblages colonize and
persist for decades with positive or negative social,
economic and biodiversity consequences'. For in-
formation on emerging ecosystems from the United
Nations Educational, Scientific, and Cultural Organ-
ization (UNESCO), see www.unesco.org/mab.
It is this concept of emerging ecosystems that led
us earlier to suggest that ecosystem diversity may actu-
ally be increasing worldwide, and it will be central to
our discussion in the remaining sections. However, even
if emerging ecosystems increase habitat diversity and
regional species diversity let us not forget that they
probably reduce species diversity at the global level.
As Sax and Gaines (2003) point out, we have not cre-
ated any new species, we have caused the extinction
of many, and those that remain have been generously
spread around the planet. The outcome of this mix-
ing and matching is still obscure and a major issue
for restoration science and practice.
We propose to consider ecosystems receiving
restoration efforts as belonging to the large and
growing number of 'emerging ecosystems'. Designer
ecosystems belong there too, even if they are usually
not designed to be autogenic or self-organizing.
Socio-ecological systems (see below) can be of many
sorts, depending on many factors, but in today's
changing world they should be seen as emerging too.
In all emerging ecosystems, we argue, a critical issue
We all know it is literally impossible to fully restore
'original' ecosystems of the past. If you play the tape
of life back, so to speak, it will never come out the
same. However, if in a given situation the goal is
restoration - as opposed to large-scale gardening, land-
scaping or fully engineered, designer ecosystems - for
reasons 1-3 listed above, then one useful approach
lies in carefully selecting an ecosystem or landscape
of reference to serve as a standard or yardstick for
the evaluation of restoration endeavours (Aronson
et al.
1993a, 1995, Aronson & Le Floc'h 1996a, 1996b).
But how can one select an
ecosystem of reference
?
This topic, which was discussed in Chapters 1 and 2
of this volume appears in a new light when we intro-
duce the notions of emerging ecosystems and socio-
ecological systems
.
If an historical orientation to
references is adapted - as is most often the case -
reconnecting some sort of ecological and cultural
continuity, or reconsolidation with some stage or
period of the local past, ranks high on the list of
desiderata. But how do we know to what extent the
period we are choosing, say the 16th century for the
Americas, or the 18th century for Australia, was itself
the most natural, or desirable, in terms of biodiver-
sity, economic productivity or natural-capital value, the
three reasons or motivations for ecological restoration
given above? Quite simply, we do not and, probably
in most cases, cannot. In Chapter 1 this was called
the moving-target syndrome.
The Canadian anthropologist and past chairman of
SER International, Eric Higgs has argued (Higgs 2003)
that an historical 'range of variability' approach
should be adopted in situations where reference con-
ditions are difficult to discern or historical informa-
tion is mostly absent. The goal in this case would
