Review of Best Practice Management and Performance Assessment of Biodiversity Offset Areas

Biodiversity offsetting is based on the approach of averting loss and/or improving biodiversity values to compensate for biodiversity values lost to development to achieve a standard of 'no net loss' of biodiversity. Offsets are defined as 'Measurable conservation outcomes, resulting from actions applied to areas not impacted by the project, that compensate for significant, adverse project impacts that cannot be avoided, minimised and/or rehabilitated/restored'(CSBI, 2015). Offsets should have a specific, and preferably quantitative, goal that relates directly to residual project impacts. Offsetting is the last step in the mitigation hierarchy (avoid, minimise, restore/rectify and offset) and is a measure of last resort after all other components of the mitigation hierarchy have been applied. Biodiversity offsetting is used as strategy to mitigate unavoidable impacts on biodiversity caused by mining development.

A biodiversity offset site is typically a parcel, or parcels of land, where native vegetation condition and threatened species habitat are protected in perpetuity and are to be improved by implementation of management actions.

To sustain its social license to operate, the coal industry must be able to demonstrate that it can effectively manage its biodiversity offset sites, referred to as Biodiversity Offset Areas1 (BOAs), and to maintain and enhance their existing biodiversity values through effective biodiversity and land management.

Many NSW mining operations implement expensive BOA management measures, such as large-scale planting programs, to accelerate the development of canopy tree density and cover. In some situations, less intensive and cheaper management approaches may represent a more appropriate and sustainable management option in the long-term. Such approaches include direct seeding or those that facilitate natural regeneration and succession, such as fencing, destocking, weed and feral animal control.

Currently, there is little more than anecdotal or individual case study data available on the application of BOA management measures and it is difficult to extrapolate experience from these programs to other situations. Indeed, there is no definitive source of information available to mine environmental managers to guide decision making on.

Fit-for-purpose monitoring and evaluation programs are required to ensure that management success can be adequately gauged, and timely adaptive management triggered where performance is suboptimal. It is acknowledged that monitoring methods and performance targets may be driven by conditions of approval or regulator expectations. However, the NSW drought in 2017-2019 exposed the inadequacies of routine biometric monitoring methods and the use of standard vegetation community benchmarks for assessing BOA management performance.

In the project team's experience, if simple temporal trends are used to assess long-term performance, year to year variation in vegetation attribute data caused by variations in annual rainfall totals can mask the positive effects of management intervention and result in missteps in adaptive management.

The key objectives of the project were to:

• Develop evidence-based decision support tools to assist environmental managers to select the most appropriate BOA management practices for their site conditions and allow them to optimise resource allocation whilst maximising biodiversity outcomes.
• Provide managers with appropriate performance attributes and reference benchmarks that better reflect important changes in BOA condition or ecological function as a result of site management.
• Examine current monitoring and data assessment methods to ensure they are robust and deliver the metrics needed to detect biodiversity gains. This will include the identification of approaches to trend analysis that can better account for data variability caused by external factors (e.g. rainfall patterns).
• Develop a guide for environmental managers on BOA monitoring, data collection and data evaluation methods to support performance and compliance assessment, and adaptive management.
• Identify research priorities to address outstanding information gaps.

The project was also originally aiming to assess emerging bushfire risks associated with BOAs and identify options for management; what the researchers found was a general lack of available information in literature and from site data on this subject. This Technical Report addresses, to a limited extent, the potential for bushfire for use in management of BOAs but the subject of emerging risk warrants further attention in future research.

There are three reports/guides that form the outcomes of this project:

1. Technical Report which contains a review of current literature surrounding BOA management, monitoring and evaluation and examines documentation from eight project partner mines and their associated BOAs
2. Management Guide; and
3. Monitoring and Evaluation Guide.