Environmental Engineering Reference
In-Depth Information
Table 4.1 Continued
Indicator type
Indicator name/
description
Process assessed
Vegetation
structure
Vegetation density and
size
Estimates the potential role of vegetation to provide positive
feedbacks (1, 4a and 4b)
Vegetation composition
Evaluates the role of different life-forms and species on positive
feedbacks (4a and 4b)
Vegetation vertical profi le
The potential for vegetation to ameliorate water and wind erosion at
ground level (2b)
Habitat complexity
Estimates the potential for the restored landscape to provide
habitats for fauna (4b).
* A gradsect is a transect oriented along a gradient such as down a slope.
** The eleven indicators in this group are combined into three synthetic indices: stability (surface resistance to
erosion), infi ltration (capacity of surfaces to infi ltrate water), and nutrient cycling (potential for soils to cycle nutrients).
*** The eight indicators in this group are used to calculate an overall index of ephemeral drainage line stability or
'health' in sections or zones down the drainage line.
useful for tabulating and summarizing indicator data.
These explanations give specifi c advice about the scale
(site, patch) at which each indicator is assessed.
To further evaluate landscape-scale restoration
progress (Figure 4.1, step 5b), data refl ecting the initial
dysfunctional state, as well as from appropriately
selected reference sites, provide a useful framework for
assessing the restoration trend. Reference sites do not
have to be exact physical and biological replicas for the
restoration sites, but ideally should have similar char-
acteristics, such as slope and surface materials, so that
surface processes are comparable (see Chapter 22).
When the monitoring system is correctly deployed,
data can be compared between restoration and refer-
ence sites almost immediately, so that differences
between them can be compared.
To evaluate progress, restorationists can graph their
monitoring data using an indicator (or a synthetic
index combining indicators) selected to refl ect biophys-
ical processes of interest, for example, the potential
of the developing soils on a restored site to cycle nutri-
ents (Figure 4.7a). The nutrient cycling index combines
a number of indicators observed in the fi eld, but it
largely refl ects assessments on the amount and state of
decomposition of plant litter. However, the nutrient
cycling index also has broader biological implications
because it implies the establishment of an effective
suite of soil biota (Oades 1984, 1993; Lavelle 1997).
Note that in this example (hypothetical, but based
on data known to be typical of restored sites; Tongway
& Ludwig 2011), the progressive trend (curve) meas-
Figure 4.7 Examples of two ways to represent the
ecological development of a restored site: (a) by graphing
values for the nutrient cycling index over six time periods
(starting at time zero) relative to the value measured on a
reference site, and (b) by plotting the six values along a line
representing a continuum of landscape functionality.
ured over six time periods is S-shaped and this trend
line is clearly towards the value expected from a refer-
ence site.
An alternative form of graph to emphasize restora-
tion progress along a gradient of landscape functional-
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