Linking Restoration and Ecological Succession (Springer ... - Inecol

Chapter 4 Retrogressive Succession and Restoration on Old Landscapes 85
2. Major disturbances (whether natural or anthropogenic) frequently accelerate
the mechanisms that underpin system retrogression, with the impact depending
on (a) the state of regression in the system prior to disturbance, and (b)
the nature of the disturbance event (i.e., intensity, scale, and what features
of the biophysical environment were most affected).
As a consequence of the above, the biophysical environment in the postdisturbance
landscape may no longer be amenable to support the original vegetation
type and may be more suited to a different vegetation composition and
structure that is better adapted, more sustainable, and more stable under the
physicochemical and hydrological conditions that characterize the new system
“state.” Defining the biophysical characteristic of this new state is the key to
successful restoration, but how can we do this and what are the main steps?
Although a huge diversity of vegetation structural types and compositions
occur on old landscapes (reflecting the myriad of physical environments and of
adaptations, attributes, and assemblages of local biota), it is possible to distill an
approach to restoration based on understanding the implications of retrogressive
succession down to seven practical steps. These are:
1. Determine the extent and stage of retrogression of the system prior to disturbance.
This is observational ecology based, if possible, on intact areas
on similar nearby landscapes. It involves the use of local knowledge, fieldwork,
and published literature to establish the broad biophysical constraints,
successional trends, and links with land-use and previous disturbance.
2. Establish the extent of the abiotic changes that have been caused by the
most recent disturbance. In essence these are the abiotic constraints that will
control the new state in which the system will be sustainable. In particular,
characterize what have been the major changes in soil hydraulic, chemical,
and biological properties. This could involve soil and terrain analysis (nutrient
status, organic matter content, compaction, and infiltration) and digital
elevation modeling (potential for sediment and organic matter transport)
3. Identify, where possible, areas in the surrounding landscape where similar
abiotic constraints associated with natural erosion or past disturbances may
be present and have resulted in a stable state that could act as “landscape
analogues” for the system requiring restoration.
4. Establish what the major species were in the pre-disturbance site and in
any natural landscape analogues. As far as possible understand their life
cycles and disturbance responses (phenology, root strategies, seed banks,
regeneration characteristics, growth rates, plasticity). This information will
provide insights into the appropriate species mix, how this can feasibly be
introduced and whether specific management interventions can accelerate
the progress of the new system toward a stable state.
5. Identify any options for management interventions to fully or partially ameliorate
the retrogression that has occurred, e.g., can critical nutrients be applied
to return the site nutrient capital to the pre-disturbance state, and is this
economically and technically feasible? Can aspects of hydrological function
be restored by soil amendment or physical or engineering treatments?
6. Establish endpoint criteria (e.g., vegetation structure, composition, productivity,
and/or function) that are compatible with the intended land use (production
systems, conservation, and stabilization) for the new “state.” Where