Remnant Rarity Index (RRI)

Brief description

The Remnant Rarity Index (RRI) describes the proportion of each NVIS major vegetation group remaining in each IBRA bioregion relative to the 1750 estimates. This approach is conceptually similar to biological status of ecological vegetation communities (EVCs) in Victoria and the biodiversity status of remnant regional ecosystems in Queensland. The RRI is therefore useful as a simple proxy for conservation status for analyses that cross jurisdictional boundaries. The RRI is solely dependent upon the difference between pre-1750 and extant vegetation mapping and does not consider additional processes such as land degradation or threatening processes.
Lineage: The RRI is calculated by analysing differences in the extent of pre-1750 and extant NVIS major vegetation groups in each IBRA bioregion across Australia. All calculations were performed on the raster products to allow for the inclusion of Tasmania, where 1750 polygons are not available. The RRI was then applied to the extant NVIS major vegetation groups, provided as part of this dataset. The methodology can be generalised to any set of vegetation maps with a consistent classification and 2 or more time steps.

Refer to Stewart et al. 2020 (linked) and the attached documentation for further details.

Note that this collection has been updated in 2023 to provide the same calculations for NVIS 6.0.