Environmental Engineering Reference
In-Depth Information
number of times (e.g. Tongway & Ludwig 2002, 2009,
2011), and have coupled it with the use of Landscape
Function Analysis monitoring data collection methods
(see section 4.2.5). Because the means to the overall
goal in the restoration of disturbed landscapes is to
repair damaged processes to achieved long-term
sta-
bility
and
sustainability
of the restored system, we
view our framework as more than just a depiction of
landscape system components and connections. We see
it as a framework that identifi es triggering events,
including natural and human-induced disturbances,
and sequences of processes where each process is con-
tingent on the effi cacy of prior processes. Learning how
disturbances affect processes can help us understand
why some landscape systems become unbalanced in
terms of gains and losses in resources over the long
term, and how these systems can be repaired.
• Was the disturbance intentionally planned, such as
in mining, or was it an unintended consequence, such
as dense woody regrowth after clearing woodland to
create pasture?
After addressing such questions, especially in terms
of an analysis of how disturbances affect landscape
processes (Figure 4.2), restorationists will have the
knowledge needed to design restoration technologies
(Figure 4.1, step 3). Step 3 is still at the 'ecological
science' level rather than at the 'engineering' level or
implementation stage (step 4). Ecological science
involves communicating how to enhance biological
and physical feedback processes, for example, by select-
ing plant species in
revegetation
projects known to be
effective for providing litter to enhance nutrient cycles
in the developing soils (Box 4.1 ).
Designing technologies to restore landscapes by
repairing processes can be relatively straightforward
(see Box 4.1). However, designing technologies can
be very challenging, such as where coal mining
operations have greatly disturbed landscapes and
major land-forming is required to reshape massive
spoil heaps. Such projects require teams of restora-
tionists with modelling and engineering skills, and
also people with the geotechnical and geochemical
knowledge about the properties and quantities of
the mine spoil materials available, such as the poten-
tial for exposure of saline, sodic or pyritic soil mater-
ials. Ecologists are needed for designing ways to
establish self-sustaining vegetation on the reformed
landscape, and for dealing with unplanned problems.
For example, if monitoring shows that
exotic weed
species
are providing most of the ground cover on a
landscape being restored, then strategies for progres-
sive replacing these weeds with more desirable and
permanent
native plant species
, while maintaining
some protective ground cover, requires careful design.
4.2.3
Designing restoration technologies
Using the above-described conceptual framework as a
tool to analyse how disturbances affect ecological proc-
esses at the level of whole systems, restorationists can
now use the information and understanding gained
from this analysis to address the problems arising from
dysfunctional processes by designing restoration tech-
nologies (Figure 4.1, step 3). To design effective restora-
tion technologies, we need to consider the following
questions:
• Was the disturbance caused by a hurricane, for
example, or was it caused by human activity, such as
mining?
• Did the disturbance factor(s) have a large impact,
such as is the case with strip mining, which requires
building new landforms, or did it entail a relatively low
impact needing only minor surface adjustments, such
as building ' brush - packs ' to reduce runoff ?
• Was the disturbance a one - off event, such as due to
woodland clearing, or is it current and ongoing, such
as due to cropping in marginal lands?
• Did the causes of disturbance extend over a long
period of time, such as livestock grazing, or was it a
brief impact, such as a wildfi re?
• Was the disturbance a rare and unpredictable event,
such as caused by a one in a hundred year fl ood, or is
it frequent and common, such as due to browsing and
grazing?
• Did the disturbance extend over large land areas or
was it restricted to small areas?
4.2.4 Implementing restoration
technologies
Once the designing step is complete, appropriate
physical or engineering works can be selected and
implemented (Figure 4.1, step 4). These technical
interventions
may vary from being diffi cult and
expensive, such as those required when restoring land-
scapes after coal-mining enterprises, to relatively easy
and inexpensive, such as the work needed to reduce the
energy of fl ows of water along trails or tracks in a park.
