Environmental Engineering Reference
In-Depth Information
tion
is simply about ' improving ' a degraded or ' useless '
site and making it useful again. The goal is to bring the
site to, or back to, a condition considered desirable and
sustainable for people, whether the use is for produc-
tion (e.g. for grazing livestock, for recreation or for
something else). In many languages, there is no clear
homologue for this word, and terms like 'environ-
mental recuperation or revitalization ' , ' enhancement '
or ' amelioration ' are more readily understandable.
'Clean-up' is often a major part of such operations, and
new terms exist for this activity as well, such as 'biore-
mediation ' and ' phytoremediation ' , as applied to oil
spills, secondarily salinized areas and other areas that
have suffered pollution or massive denaturalization.
It is important to recall that at the scale of whole
landscapes
, where
socio - ecological ecosystems
co-occur and interact with each other, all three activi-
ties can be planned and pursued simultaneously. Once
the goals for a given landscape unit - restoration, reha-
bilitation and/or reclamation - have been set, indicator
values can be used for diagnostic purposes, as early-
warning indicators of deviations, or otherwise in the
process of piloting a system along a target
trajectory
.
In this topic we will not go into monitoring and evalu-
ation of socio-economic, cultural and moral values.
Ecological evaluation values are often based on
indi-
cator species
, members of a biotic community that
have been shown (by experience or by scientifi c calibra-
tion) to be characteristic of certain environmental con-
ditions and sensitive to changes therein (e.g. Ellenberg
et al
. 1991 for plants; Carignan & Villard 2002 for mul-
tiple species; Harris 2003 for microorganisms). They
can be used to qualify the direction of changes in an
ecosystem, that is, by distinguishing between develop-
ing and degrading ecosystems. Note, however, that
quantitative indicator values of species that have been
asserted in a specifi c region may not be applicable to,
and thus have to be calibrated for their use in, the envi-
ronmental context of other regions.
planning and executing an ecological restoration - or
rehabilitation - project (SER 2004 ; Clewell & Aronson
2007). When no such site or system exists, it is neces-
sary to construct a reference from available informa-
tion and knowledge about what did exist in the past,
within the limits of a well-defi ned so - called
normal
functioning
(van Andel
et al
. 1987 ) and
historical range
of variability
(Higgs 2003 ).
Considerations of natural dynamics and environ-
mental changes imply that reference systems, which
we know or construct from past or from present undis-
turbed areas relevant to our site, can serve as models
to orient and inspire us, rather than as a strict objective
to be literally reached. The reference serves the role of
a 'guiding vision' but also provides a multidimensional
yardstick or benchmark, to be used for the comparison
of what is happening to the ecosystem undergoing res-
toration with respect to our prespecifi ed goals for it. It
is not a romantic or naive notion of trying to return
somehow to the past, something we know is not pos-
sible. Inspired by the knowledge of the process of evo-
lution of species - an ongoing process that does not
start from scratch,
de novo
, but inevitably has historical
roots - a restoration scientist should gather as much
information as possible to understand the historical
development and, where appropriate, the human
transformation of the ecosystems and landscapes to be
restored.
For purposes of nature conservation and restoration,
in many parts of the world there are often adequate,
appropriate and well-documented historical references
available, sometimes even
in situ
, dating for example
from the late nineteenth or early twentieth century.
Often, however, for example within the vast Euro-
Mediterranean region, with its intricate tapestries of
seminatural and managed ecosystems, the choice or
construction of a reference model is quite complicated,
and polemical, involving much discussion and negotia-
tion. We are of the opinion, however, that it is a worth-
while endeavour (see Clewell & Aronson 2007).
2.2.4
Reference ecosystems
2.2.5
Zooming in on ecology
Central to the goal-setting process in projects and pro-
grammes of ecological restoration is the concept of
reference ecosystems
. The choice or construction of
a reference ecosystem, or more simply 'the reference',
in restoration ecology consists of identifying one or
more natural, or seminatural, ecosystems (or descrip-
tions thereof) which can serve as models or targets for
After having emphasized the need for inter- and trans-
disciplinarity, we now zoom in on key ecological topics.
In the
SER Primer on Ecological Restoration
(SER 2004 ),
and in Clewell and Aronson (2007), nine
attributes
of restored ecosystems
are proposed for consideration.
These are (1) a characteristic assemblage of the species
