Remnant Rarity Index (RRI)

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. \nLineage: 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. \n\nRefer to Stewart et al. 2020 (linked) and the attached documentation for further details. \n\nNote that this collection has been updated in 2023 to provide the same calculations for NVIS 6.0.\n残存稀有度指数（Remnant Rarity Index，RRI）描述了各IBRA生物地理区内，相较于1750年的基准估算值，现存NVIS主要植被类群的留存比例。该方法在概念上与维多利亚州的生态植被群落（Ecological Vegetation Communities，EVCs）生物状况、以及昆士兰州残存区域生态系统的生物多样性状况相仿。因此，RRI可作为跨辖区分析中衡量保护状况的简易替代指标。RRI仅基于1750年前与现存植被制图的差异计算，未考虑土地退化、威胁因子等其他生态过程。 数据谱系：RRI通过分析澳大利亚全境各IBRA生物地理区内，1750年前与现存NVIS主要植被类群的分布范围差异完成计算。所有计算均基于栅格产品开展，以纳入塔斯马尼亚州的数据——该地区无1750年植被多边形矢量数据。随后，将计算得到的RRI应用于本数据集附带的现存NVIS主要植被类群。该方法可推广至任何具备统一分类体系、且包含2个及以上时间节点的植被制图集。 如需了解更多细节，请参阅Stewart等人2020年的关联文献及随附文档。 请注意，本数据集合集已于2023年完成更新，可针对NVIS 6.0版本提供同款计算结果。