What is the Basis for Assessing Rehabilitation Success? Part 1

Found in: News

Is this area representative of the performance of the entire landform? 

Part 1 – What are Completion Criteria?

The theme for this series of articles comes from a recent journal paper published in Restoration Ecology titled “Should reference conditions be drawn from a single 10ha plot? Assessing representativeness in a 10,000 ha old-growth European beech forest” (Peck et al 2015). Although the context of the journal article is different to the setting of completion criteria and monitoring of rehabilitation performance for mining projects in Australia – they have the same requirement to cost-effectively collect representative data over a large area.

In this article Katina Strelein, Astron’s Principal Scientist – Rehabilitation, provides background information on setting appropriate completion criteria and the requirement for good data for this process. The following articles cover the importance of identifying and understanding a suitable analogue ecosystem (or other benchmarks against which rehabilitation success can be measured) and a method for collecting representative data over a large area.

Completion Criteria – What are they, how are they set and why are they important? 

Completion criteria provide the basis for concluding when rehabilitation has been satisfactorily achieved (DMP/EPA 2015). Sounds pretty simple – but setting effective completion criteria is a very difficult task as they need to:

  • Be appropriate - which principally entails ensuring that the criteria set a standard for achieving a post-rehabilitation outcome that is:

o relevant to the area and the key risks of the site
o acceptable to key stakeholders (who can have conflicting requirements).

Key stakeholders generally include as a minimum the mining company (and its staff), regulators, land owners/managers (such as private land holders, indigenous/traditional land owners, lease holders) and local communities or groups.

  • Be achievable - both physically (with respect to the capacity of the land and the materials available) and economically.
  • Make sense and be specific – so that when you are trying to get your stakeholders to sign off to say that you have met the completion criteria (potentially up to 20 or more years after they were agreed upon) everyone understands what it is you are meant to achieve. Once again – this sounds simple but is very hard to achieve in practice, particularly when dealing with ecosystems which are almost always complicated. For example, consider a criterion to achieve 70% of the species diversity of an analogue ecosystem in the rehabilitation area. Is this based on the mean diversity of all the transects you have in the analogue ecosystem? Or the highest value? What is diversity? Is it the number of species recorded in a transect? Is it the diversity recorded in your analogue ecosystem this year? Or the average over the time you have been recording? Does diversity include annual species or only perennial species? Do all of your rehabilitation transects have to individually meet the criterion? Or on average?
  • Have a scientific basis – having a scientific basis for completion criteria (such as results from rehabilitation trials) is the key to achieving the first two points as it provides reassurance to the key stakeholders and provides information on what can be achieved. 

In terms of revegetation, things that need to be considered in the setting of completion criteria include:

  • Identification of the key attributes (such as cover or species composition) that need to be assessed as they make the most contribution to successful rehabilitation. 
  • Whether completion criteria should be based on comparison to an analogue vegetation type of community. If so, what is an appropriate analogue to compare to? Or is there a better basis for judging rehabilitation success (for example the return of keystone species)?
  • Identification of an appropriate criterion to be reached. Is it realistic to expect rehabilitation to have the same level of vegetation cover as undisturbed vegetation? Or should 70% of the cover in the surrounding vegetation be reached? In what timeframe should this be expected to be achieved? If there are some areas with lower vegetation cover does this mean the whole rehabilitation area fails, and what scale is the criterion applied to? 

The collection of high quality data at an appropriate scale (both spatially and temporally) that is representative of the area of interest is critical to answering the questions above and forming the basis for setting completion criteria that are appropriate and achievable. Stay tuned for the next article in this series which covers in more detail why understanding your analogue or reference ecosystem is critical if completion criteria are based on comparison with them.

 
References:

Department of Mines and Petroleum (DMP) and Environmental Protection Authority (EPA) 2015, Guidelines for Preparing Mine Closure Plans.

Peck JLE, Commarmot B, Hob ML and Zenner EK 2015, ‘Should reference conditions be drawn from a single 10 ha plot? Assessing representativeness in a 10,000 ha old-growth European beech forest’, Restoration Ecology, vol 23(6), pp. 927-935

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