Aggregated Counts and Lists of Native Species in Terrestrial Bioregions 1900-2023

Species occurrence data from the Atlas of Living Australia (ALA), between 1900 and 2023, were used to create data summaries of native species in terrestrial bioregions (IBRA7). This data collection comprises two datasets: counts of native species in each terrestrial bioregion, and lists of native species with taxonomic information and EPBC status in each terrestrial bioregion.

The counts of native species by bioregion informed an analysis of change in the proportion of species likely to persist over the very long term (S), using the species-area relationship (SAR) with a z-value of 0.25 (S = A^z), and average condition (A) within each bioregion over a time series from the Habitat Condition Assessment System (HCAS) version 3.0. A national-level indicator can then be derived as a species richness weighted average of the bioregional analysis. The counts of EPBC Act threatened species by bioregions is used to inform an interpretation of the condition status of each bioregion. The lists of native species by bioregion provide a basis for an updated analysis that takes into account the fact that species are shared between bioregions and this has an impact on the proportion of species likely to persist over the very long term, when summarised at a national level. These outputs support interpretation of the HCAS and National Connectivity Index (NCI) for the Australian Government’s environment corporate performance measure EN01 (2023-24 Annual Report of the Department of Climate Change, Energy, the Environment and Water). This data collection may also be relevant for other types of analysis at the bioregional level or with different data inputs for the SAR analysis.

The ALA aggregates data from hundreds of different data providers, using different methods, into a single database. Consequently, observations in the ALA display spatial, temporal, and taxonomic bias that ensure care must be taken in their interpretation in downstream analysis. When summarising to the bioregional scale, survey effort is broadly correlated with accessibility, meaning that bioregions near major cities may appear disproportionately biodiverse relative to more remote regions.