SECTION 2 - Six Key Principles of Ecological Restoration Practice
Six key principles are used here to provide
a framework for conceptualising, defining and measuring ecological restoration,
particularly at a time of rapid environmental change. (See also Appendix
2 Values and principles underpinning ecological restoration.)
Principle 1. Ecological restoration practice
is based on an appropriate local indigenous reference ecosystem
A fundamental principle of ecological restoration
is the identification of an appropriate reference ecosystem to
guide project targets and provide a basis for monitoring and assessing
outcomes. The reference ecosystem
can be an actual site (reference site) or a conceptual model synthesised
from numerous reference sites, field indicators and historical and predictive
records. It includes local indigenous plants, animals and other biota characteristic of the pre-degradation ecosystem. (For exceptions see Box 1). The reference ecosystem may also include species from neighbouring
localities that have recently naturally migrated e.g. due to a changing
climate (see definition of ‘local indigenous ecosystem’ in
glossary). Where local evidence is lacking, regional information can help
inform identification of likely local indigenous ecosystems. Identifying
a reference ecosystem involves analysis of the composition (species),
structure (complexity and configuration) and function (processes
and dynamics) of the ecosystem to be restored on the site. The model should
also include descriptions of successional states that may be characteristic
of the ecosystem’s decline or recovery.
A reference ecosystem is a model adopted to identify the particular ecosystem that is the target of the restoration project. This involves describing the specific compositional, structural and functional ecosystem attributes requiring reinstatement before the desired outcome (the restored state) can be said to have been achieved.
Australia’s landmass, waterways and marine
areas contain many intact or remnant indigenous ecosystems. The site's
pre-degradation ecosystems are used as starting points for identifying
restoration targets - taking into account natural variation and acknowledging
the fact that ecosystems are dynamic and adapt and evolve over time, including
in response to changing environmental conditions. That is, we use existing
and recent assemblages, coupled with sound scientific and practical knowledge
of current and future environmental conditions, to help identify suitable
reference ecosystems. Where irreversible altered topography, hydrology,
or climatic conditions have occurred or are predicted; a local indigenous
ecosystem more ecologically appropriate to the changed conditions may
be used as a guide (see caveats below in Box 1).
Adopting a reference ecosystem is therefore not an attempt to immobilize
an ecosystem at some point in time but to optimise potential for local
species to recover and continue to evolve and reassemble over subsequent
Identifying functional components of a reference ecosystem is important
to goal setting; but returning functions also facilitates restoration.
That is, recovery is achieved by the processes of growth, reproduction
and recruitment of the organisms themselves over time, facilitated by
the return of appropriate cycles, flows, productivity levels and specific
habitat structures or niches. Monitoring of the recovery process is required
to identify whether acceptable trajectories of recovery are likely to
result in a self-organising and functional ecosystem or whether further
(or different) interventions are needed to remove barriers to recovery.
See Genetics, fragmentation and climate change - implications.
Box 1. Reference ecosystems in cases of irreversible human-mediated
Many local sites, intact or degraded, are becoming increasingly threatened by human activities and some of these result in effectively irreversible impacts. Reinstating local indigenous ecosystems in cases where irreversible environmental change has occurred requires anticipation and, if necessary, mimicry of natural adaptive processes.
1. Irreversible physical (soil and water) and biological changes.
In cases where insurmountable environmental
change has occurred to the site and the pre-degradation ecosystem
cannot be reinstated, an appropriate solution would be to establish
an alternative, locally occurring ecosystem better suited to the
changed conditions. (Examples include sites where hydrology has
changed irreversibly from saline to freshwater or vice versa, traditional
fire regimes cannot be reinstated, or where erosion has produced
a rocky platform). This approach has in the past been called 'creation'
or 'fabrication' but is more usefully labelled 'conversion'. Whether
a conversion would be considered ecological restoration or rehabilitation
depends on there being a reasonable likelihood of achieving a viable
local indigenous ecosystem; the magnitude of the change; and, social
perceptions of compensation for loss or damage. That is, shifting
to an alternative ecosystem would not be considered restoration
or rehabilitation if it were used to sidestep addressing the physical
conditions of a site - and is likely to be considered rehabilitation
rather than restoration where irreversible change to an ecosystem
is contemporary and deliberate (e.g. associated with a current industrial
or urban development).
Where biological degradation cannot be reversed, the next best alternative
would be rehabilitation to the highest practicable ecological functionality,
with as high as possible similarity to the reference ecosystem.
Examples of conversion.
2. Accelerated and irreversible climate change.
A changing climate means that all local ecosystems
are likely to be changing at faster rates than in the past; in ways
that are difficult to anticipate. Some entire ecosystems will be
destroyed (e.g. many marine, coastal, alpine and cool temperate
communities) where no suitable migration habitats exist; while in
other ecosystems, species may have a capacity to adapt by genetic
selection or migration, options that are less likely under conditions
of fragmentation (Appendix
3: Genetics, fragmentation and climate change - implications).
Climate change is recognised as an anthropogenic degradation pressure
that requires urgent and unfaltering mitigation of its causes, mitigation
that needs to be embraced by the whole of society. Even with optimal
mitigation, however, much of this change is irreversible and therefore
becomes part of the environmental background conditions to which
species need to adapt or be lost. To assist potential adaptation,
target-setting needs to be informed by research into the anticipated
effects of climate change on species and ecosystems so that reference
ecosystems and restoration targets can be modified as required (Appendix
Where fine scale changes in temperature or moisture levels are expected
to affect only some species at an individual site, adaptability
can be improved by ensuring the restoration includes a high diversity
of the site's other pre-existing species, some of which may be suited
to the changed conditions. In cases where the climate envelope of
the species is expected to shift as a result of climate forecasts,
introducing more diverse genetic material of the same species from
other parts of a species' range is often recommended; at least in
fragmented landscapes or aquatic environments where migration potential
is lower than intact areas (Refer to Appendix
3). As a rule of thumb, managers need to optimise potential
for adaptation by retaining and enhancing genetically diverse representatives
of the current local species in configurations that increase linkages
and optimise gene flow. Such adaptation is maximised where all threats
affecting ecosystems (particularly fragmentation) are minimised.
In the final analysis, however, the role of restoration is to 'assist recovery' not
impose a human-design upon it - that is, to reinstate ecosystems
on their trajectory of recovery so that their constituent species
may continue to adapt and evolve. The Standards recommend practitioners
continue with restoration aspirations based on local reference ecosystems,
but be ready to adapt these in the light of observable or likely
changes occurring within these local ecosystems, as informed by
sound science and practice.
renewing linkages in landscapes.
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