Environmental Engineering Reference
In-Depth Information
Periodic
clear-cutting
Primary-type
mixed-oak forest
Thinning of pine
and encouragement
of oak regeneration
Natural
regeneration
Managed
shrublands,
coppices
Pine-dominated
forest
Selective
logging and
cutting
clearing,
ploughing
Olive orchards,
vineyards and
pastures
Agroforestry
development
Open woodlands
abandonment
Clear-cutting
Logging
Improved
management
Destroyed
forest
Multipurpose
forest
degration
restoration
rehabilitation
reallocation
transitional or
metastable state
process
Plantations
Tree farms
Agroforestry
development
Fig. 17.2
State and transition model for a
Pinus halepensis
woodland in Mediterranean France showing
degradation pathways and various possible responses. Modified from Gondard
et al.
(2003).
Note that no values are given, and no species axes or
dimensions are indicated on this figure, as is typical
of state and transition models. However, choices
taken about which pathways to foster or favour must
depend on a combination of ecological and socio-
economic deliberations and negotiations, ideally with
a natural-capital approach getting the attention it
deserves, along with various social, ecological and
cultural concerns. It is to be noted that the Society
for Ecological Restoration International Primer (SER
2002; www.ser.org) states clearly that ecological
restoration is intentional, but that the succession
pathways labelled as restoration can either be entirely
passive - that is, spontaneous regeneration - or
else carefully monitored and adjusted by on-going
management.
An alternative - or complement - to the idea of real,
existing reference areas is provided in the SER Primer,
under the rubric 'Attributes of restored ecosystems'.
When no historical reference is available or adequate,
as is very often the case in Europe, this approach
can help orient the ecological restoration programme.
It would also apply to emerging ecosystems when
present conditions do not allow the recovery of a
degraded ecosystem to a known historic condition. To
express this idea, and to continue the ideas given on
this subject in Figs 16.1 and 16.2, Fig. 17.3 provides
a schematic description of the new approach to eco-
logical restoration we espouse, which aims to reconcile
the reality of emerging ecosystems, and the growing
prevalence of socio-economic systems, with the funda-
mental notions of ecological restoration, including the
potential value of historical reference systems.
On the left-hand
y
-axis of Fig. 17.3, note that all
three 'whys' for ecological restoration (see section 16.1)
are combined in order to go beyond previous
