Principle 4 The goal of ecological restoration is full recovery, insofar as possible, even if outcomes take long timeframes or involve high inputs.

Qualification of a project as an ecological restoration activity is not determined by the duration of the project but by the intent to achieve the highest and best level of recovery possible. It is important to bear in mind that the desired outcome may take long timeframes. This can be because sufficient time has not yet elapsed for recovery processes to run their course; sufficient restoration resources or knowledge are not yet available to overcome recovery barriers; or mitigating impacts originating from outside the site require lengthy negotiation. While success can be achieved ultimately by continuous improvement over time in many cases (e.g. non-mandatory cases), the achievement of full recovery would require more substantial human and financial investment including in- depth research where only relatively short timeframes are available (e.g. many mandatory restoration cases).

To help managers track progress towards project goals over time, the Standards offer a tool (five-levels or ‘stars’) for progressively assessing and ranking degree of recovery over time. This tool is summarised in Table 1 and more fully described, relative to the six attributes of ecological restoration, in Table 2.

Five-star recovery—that is, where the ecosystem is on a self-organising trajectory to full recovery based on an appropriate local indigenous reference ecosystem—is the standard to which ecological restoration projects ideally aim. However, in some cases, constraints may limit potential to less than full level of recovery. Such cases can still be referred to as ecological restoration projects as long as the aim is for substantial recovery relative to the appropriate local indigenous reference ecosystem. However, projects that aim for low levels of recovery—or solely recovery of ecosystem functions without including the appropriate local biota—are better referred to as rehabilitation (Appendix 1).

Table 1 Summary of generic standards for one to five star recovery levels. Note 1: Each level is cumulative. Note 2: The different attributes will progress at different rates—see Table 2 that shows more detailed generic standards for each of the six attributes.

Number of stars Recovery outcome, modeled on an appropriate local indigenous ecological reference
1 Ongoing deterioration prevented. Substrates remediated (physically and chemically). Some level of indigenous biota present; future recruitment niches not negated by biotic or abiotic characteristics. Future improvements for all attributes planned and future site management secured.
2 Threats from adjacent areas starting to be managed or mitigated. Site has a small subset of characteristic indigenous species and there is low threat from undesirable species on site. Improved connectivity arranged with adjacent property holders.
3 Adjacent threats being managed or mitigated and very low threat from undesirable species on site. A moderate subset of characteristic indigenous species are established and evidence of ecosystem functionality commencing. Improved connectivity in evidence.
4 A substantial subset of characteristic biota present (representing all species groupings), providing evidence of a developing community structure and commencement of ecosystem processes. Improved connectivity established and surrounding threats being managed or mitigated.
5 Establishment of a characteristic assemblage of biota to a point where structural and trophic complexity is likely to develop without further intervention other than maintenance. Appropriate ecosystem exchanges are enabled and commencing and high levels of resilience is likely with return of appropriate disturbance regimes. Long term management arrangements in place.

Notes for interpreting the five-star evaluation system

  1. The five-star system has been designed to evaluate the progression of an ecosystem along its recovery trajectory. It is not a tool for evaluating the practitioner.

  2. The five-star system represents a conceptual gradient, providing a framework that can be interpreted by managers, practitioners and regulators in more quantitative terms to suit a specific ecosystem. The indicators described here are generic and provided as a guide only. This means that the indicators or metrics used to specifically describe and interpret recovery at each ranking level for a specific ecosystem need to be interpreted for each project.

  3. Evaluation can only be as rigorous (and therefore as reliable) as the monitoring that informs it. As some projects can only provide informal monitoring, evaluation needs to transparently specify the level of detail and degree of formality of the monitoring from which the conclusions have been drawn. This means that Figure 2 or an evaluation table cannot be used as evidence of restoration success without the monitoring report on which it is based.

  4. Each restoration project does not necessarily start at a one-star ranking. Sites that involve remnant biota and unaltered substrates will start at a higher ranking—while sites where substrates are impaired and/or biota are absent will start at a lower ranking. Whatever the entry point of a project, the aim will be to progress the ecosystem along the trajectory of recovery towards a five-star rated recovery.

  5. Although the ideal aim is to achieve a five-star rating for all attributes in a restored system, full recovery of some attributes will be difficult to achieve at larger scales. Complete removal of external threats in a fragmented landscape or aquatic environment, for example, is usually beyond the scope of site-specific restoration project but reduction of these threats may be possible (e.g. pollution regulation, ‘no take’ zoning, installation of nutrient filters, ongoing control of pest species etc). Assessment of ongoing threat levels should be in place at the restoration site. If removal or reduction of external threats is not fully achievable, monitoring and reporting needs to indicate whether this is the result of external constraints and to what extent these are resolvable.

  6. Evaluation using the five-star system and Figure 2 must be site- and scale-specific. An evaluation will provide more detail when applied at the scale of an individual project or site. However multiple evaluations can be aggregated to inform degree of recovery in larger programs. Where larger scale projects retain substantial areas of permanently converted industrial activity or urban development, scores will necessarily be lower. Nonetheless, in such situations additional detail in supplementary reporting can capture even low level gains at larger scales where these are important for some species or ecological processes. Similarly, in social-ecological systems, progress with important social outcomes of the project (such as increasing level of capacity and stewardship commitment by stakeholders) can be reported separately to capture social elements.

Table 2 Generic one-to-five-star recovery scale interpreted in the context of the six attributes used to measure progress towards a restored state. (Note: this five-star scale represents a gradient from very low to very high similarity to the reference ecosystem. It provides a generic framework only; requiring users to develop indicators and a metric specific to their system and ecosystem type.)

Attribute One-star Two-star Three-star Four-star Five-star
Absence of threats Further deterioration discontinued and site has tenure and management secured. Threats from adjacent areas beginning to be managed or mitigated. All adjacent threats being managed or mitigated to a low extent. All adjacent threats starting to be managed or mitigated to an intermediate extent. All threats managed or mitigated to high extent.
Physical conditions Gross physical and chemical problems remediated (e.g.contamination, erosion, compaction). Substrate chemical and physical properties (e.g. pH, salinity) on track to stabilise within natural range. Substrate stabilised within natural range and supporting growth of characteristic biota. Substrate maintaining conditions suitable for ongoing growth and recruitment of characteristic biota. Substrate exhibiting physical and chemical characteristics highly similar to that of the reference ecosystem with evidence they can indefinitely sustain species and processes.
Species composition Colonising indigenous species (e.g. ~2% of the species of reference ecosystem). No threat to regeneration niches or future successions. Genetic diversity of stock arranged and a small subset of characteristic indigenous species establishing (e.g. ~10% of reference). Low threat from exotic invasive or undesirable species. A subset of key indigenous species (e.g. up to 25% of reference) establishing over substantial proportions of the site, with nil to low threat from undesirable species Substantial diversity of characteristic biota (e.g. up to 60% of reference) present on the site and representing a wide diversity of species groups. No inhibition by undesirable species High diversity of characteristic species (e.g. >80% of reference) across the site, with high similarity to the reference ecosystem; improved potential for colonisation of more species over time
Structural diversity One or fewer strata present and no spatial patterning or trophic complexity relative to reference ecosystem. More strata present but low spatial patterning and trophic complexity, relative to reference ecosystem. Most strata present and some spatial pattering and trophic complexity relative to reference site. All strata present. Spatial pattering evident and substantial trophic complexity developing, relative to the reference ecosystem All strata present and spatial pattering and trophic complexity high. Further complexity and spatial pattering able to self-organise to highly resemble reference ecosystem.
Ecosystem function Substrates and hydrology are at a foundational stage only, capable of future development of functions similar to the reference. Substrates and hydrology show increased potential for a wider range of functions including nutrient cycling, and provision of habitats/ resources for other species. Evidence of functions commencing— e.g. nutrient cycling, water filtration and provision of habitat resources for a range of species. Substantial evidence of key functions and processes commencing including reproduction, dispersal and recruitment of a species. Considerable evidence of functions and processes on a secure trajectory towards reference and evidence of ecosystem resilience likely after reinstatement of appropriate disturbance regimes.
External exchanges Potential identified for reinstating exchanges (e.g. of species, genes, water, fire) with surrounding landscape or aquatic environment. Connectivity for enhanced positive (and minimised negative) exchanges arranged through cooperation with stakeholders and configuration of site. Connectivity increasing and exchanges between site and external environment starting to be evident (e.g. more species, flows etc) High level of connectivity with other natural areas established, observing control of pest species and undesirable disturbances. Evidence that potential for external exchanges is highly similar to reference and long term integrated management arrangements with broader landscape in place and operative.