Limits to impact restoration

4. Limits to impact restoration

Where it is not possible to avoid and minimise all impacts, the feasibility of ecological restoration is determined, with particular consideration given to the biodiversity elements for which the site is identified as a KBA (as documented in the World Database of Key Biodiversity AreasTM), and restoration is conducted where it is ecologically feasible. A precautionary approach to ecological restoration should be applied, particularly when predicting restoration success as part of residual impact estimates. Empirical expert advice and best available scientific evidence is essential to determine the feasibility and effectiveness of restoration plans. Furthermore, it is recommended that the limits to offsets established by the IUCN Policy on Biodiversity Offsets should also apply to the restoration of the project’s impact, and that the restorationpotential, including in the light of climate change, is demonstrated before project activities commence.


How can the World Database of Key Biodiversity AreasTM help? The World Database of Key Biodiversity AreasTM can be used to identify which habitat types occur in the KBA, to help focus additional research on restoration success for those habitat types in other KBAs and sites.


More about this guideline

Notwithstanding the fact that, for on-going projects affecting KBA trigger element(s), restoration of a project’s or operation’s impacts is certainly a desirable type of intervention and outcome, the KBA Partners have recognised that new projects should carefully assess the potential outcomes of impact restoration measures when estimating the potential residual impact of the project and operations.

According to the Society for Ecological Restoration, ecological restoration is the process of assisting the recovery of an ecosystem that has been damaged, degraded, or destroyed. In this context, it means trying to repair unavoidable or accidental damage done to a Key Biodiversity Area (KBA) during operations. In addressing impacts in a KBA, it is critical that restoration efforts specifically target KBA trigger elements (e.g. species, ecosystems, biological processes, along with other important biodiversity features) and that the restoration measures are designed to restore the features to baseline levels or higher.

Restoring a natural ecosystem is an uncertain, complex, and costly process, and does not always succeed. To maximise the chances of success, restoration programmes must follow a number of steps (see Figure 1).

Figure 1. The stages and elements of leading practice restoration planning and implementation. (Adapted from Anstee, 2016)

Ecosystems vary in the ease with which they can be restored and how much is known about restoration techniques. Limits to restoration may include the following:

  • Restoration of a site with unique biodiversity is not possible where the site is the sole or one of few remaining sites and restoration of the unique biodiversity feature once lost is not feasible.
  • Time required to restore a biodiversity feature, e.g. restoration of 1,000-year-old trees is unlikely to be feasible.
  • Limitation of resources, for example in arid or semi-arid landscapes where the physical or nutrient quality of soils or rainfall availability may prevent adequate restoration.
  • Restoring unique ecological characteristics resulting from interactions of biodiversity features at a specific site may not be feasible.

The scale and type of project impacts (for example, mining versus agriculture versus forestry), together with local environmental factors coupled with policy or regulatory requirements, affect a project’s ability to achieve restoration success (as defined by the restoration targets and objectives). This is particularly pronounced where physical resources are limited (for example, the physical or nutritional quality of soil, rainfall availability and predictability), such as in many arid and semi-arid landscapes across the globe. Combined with the scale of the disturbance from the project’s impacts on the environment, such local environmental factors greatly influence the likelihood that restoration efforts will be successful (see Figure 2).

Figure 2. The relationship between the level of disturbance and the level of possible intervention, and the relationship between the degree of ecosystem change and the financial cost of restoration. (Adapted from Anstee et al. 2016)

There is still a lot to learn about restoration and how successful outcomes can be achieved as part of the mitigation hierarchy. Fortunately, restoration ecology is a growing and active scientific field, and there are considerable resources and expertise available to businesses working in KBAs. Companies need to consider the feasibility of restoring specific biodiversity features within a reasonable time frame before assuming that restoration is a good option.

A restoration plan in a KBA can usefully be guided by the objectives, desk-based research, and baseline information related to the trigger biodiversity element that has been affected by the business operations. The restoration process can also:

  • engage technical restoration specialists in research institutes and consultancies who have a detailed knowledge of the habitats that will be restored;
  • involve stakeholders (both community and government) in the development and assessment of restoration success criteria; 
  • make use of a range of software that is available to help companies optimise the costs of landform design and construction; and
  • remain aware that restoring a natural ecosystem after industrial disturbance is a complex and costly process, and opportunities to redo unsuccessful rehabilitation works are often limited.

In general, preventive measures (such as avoidance and minimisation of impacts) are considered the most effective options, both in terms of conservation outcomes and financial considerations. On the contrary, restoration is much more challenging, as there are a number of situations where the restoration of impacts has proven extremely difficult or practically impossible, due to the specific ecological, biological, and socio-cultural conditions.

For this reason, the KBA Partners have recommended that the limits to offsets identified in the IUCN Policy on Biodiversity Offsets also apply to restoration efforts.

Case study: Habitat restoration in limestone quarries

References and Resources

Anstee, S., Bennun, L., Temple, H., and Dutson, G. (2016). Biodiversity Management: Leading practice sustainable development programme for the mining industry. Department of Industry, Canberra, Australia.