Reference Benchmarks

Benchmark data for endemic vegetation attributes (such as basal area and biomass) is not available for this region of Western Australia (WA). Instead, data was collected from “best on offer” reference sites, which are the most intact examples of native vegetation available. These included pockets of remnant vegetation on the farms and along roads and infrastructure corridors. Sites were identified through remote sensing and ground truthing, with expert opinion used to select the best available example for each sub-asset. The method allows for this approach, and it was discussed with Accounting for Nature during registration.

The Environmental Account used one reference site per sub-asset which has its limitations, including sensitivity to error and statistical robustness. It was considered a reasonable approach because adding lower-quality sites would reduce benchmark quality, and data in the region is scarce. Expert calibration also reduced the risk of site bias. Because best on offer sites are not pristine, condition scores may be skewed slightly higher. This is a recognised compromise in a wheatbelt landscape that has been heavily modified by agriculture.

Accuracy of vegetation survey and mapping

Vegetation surveys and mapping rely on sampling and on interpreting field and remote sensing data, so they do not cover the whole landscape. Experienced Western Australian ecologists carried out the work using proven methods. Survey results are therefore considered reliable, and detail is expected to improve as more data becomes available. WA pre-cleared vegetation datasets were used to divide the account area into sub-assets. These are less detailed than datasets available in some other states, but the method allows for their use.

Technical challenges in restoration

Restoring cleared cropping land to the native woodland that existed before clearing is technically challenging. Soil function, nutrients, hydrology and wildlife interactions can all limit how quickly condition improves. Weeds and sourcing suitable species add further challenges and climate change is altering conditions in the northern wheatbelt. To manage these risks, the owners have engaged a restoration practitioner with more than 30 years of local experience, a local provenance native nursery, a carbon advisor and a consulting ecologist. They are also committed to monitoring and maintenance throughout the life of the project.