Environmental Engineering Reference
In-Depth Information
Table 1.1
Information available for
different types of reference system.
Availability of information
Type of system
Present status
Memory
Records
Forensic
Current
+
+
+
+
Recent
−
+
+
+
Past
-
-
+
+
Prehistoric
-
-
-
+
+
, Available;
−
, not available.
pean countries, many red-list species, etc.) are in
fact short-lived degradation phases of peat-forming
communities. Another problem with modern reference
ecosystems is that the reference ecosystem may itself
be under threat due to the changes in the Earth sys-
tem wrought by anthropogenic pressure, as outlined
in the first section of this chapter; for example,
global climate change might make lowland wet
grasslands unsustainable due to changes in rainfall and
hydrological regime.
Restoration?
Restoration?
DEGRADED
ECOSYSTEM
Perturbation
Undisturbed trajectory
ORIGINAL
ECOSYSTEM
CURRENT
ECOSYSTEM
Time
Functional targets
Fig. 1.5
Time changes an undisturbed ecosystem,
making targets from the past hard to determine.
When using functional targets we have some idea
of the gross parameters we have to measure (primary
productivity, energy flows, hydrological regime),
and success in restoring these functions indicates a
certain level of integration. Unfortunately for the
restorationist they are nearly all emergent properties,
and not directly capable of manipulation. As we have
indicated above superficial success may be garnered
by a massive species re-introduction, only to be fol-
lowed by a catastrophic failure. But they do give us
a coherent and cogent set of targets, and we should
adopt their use because the success of these functions
is self-consistent. The outcome does not rely on the
judgement of human agency.
Modern reference ecosystems
Of more immediate practical use is the deployment of
a reference system based on modern likely equivalents:
what would be here in this defined topographic unit
if degradation had not taken place? This immediately
addresses the problem of moving-target syndrome,
described above, as by definition all biotic components
will at least be available to some degree, and we may
take measurements aimed at capturing the key attrib-
utes of the modern reference system which we aim
to achieve in the restored system. A problem with
modern reference ecosystems is that we do not know
whether they occur around their optimum or are in
fact also found under sub-optimal conditions. For
example, Grootjans and van Diggelen (1995) suggested
that many sites with
Caricion davallianae
vegetation
(EU priority habitat, heavily protected in most Euro-
Ecosystem service to society targets
Setting our targets from the various categories above
in an ecosystem-service context is the only way in
which we are going to produce truly self-sustaining
restored ecosystems. As Cairns (2000) reminds us:
'Major ecological restoration will not be undertaken
