A national-scale dataset for threats impacting Australia's imperiled flora and fauna

Abstract

Australia is in the midst of an extinction crisis, having already lost 10% of terrestrial mammal fauna since European settlement and with hundreds of other species at high risk of extinction. The decline of the nation's biota is a result of an array of threatening processes; however, a comprehensive taxon-specific understanding of threats and their relative impacts remains undocumented nationally. Using expert consultation, we compile the first complete, validated, and consistent taxon-specific threat and impact dataset for all nationally listed threatened taxa in Australia. We confined our analysis to 1,795 terrestrial and aquatic taxa listed as threatened (Vulnerable, Endangered, or Critically Endangered) under Australian Commonwealth law. We engaged taxonomic experts to generate taxon-specific threat and threat impact information to consistently apply the IUCN Threat Classification Scheme and Threat Impact Scoring System, as well as eight broad-level threats and 51 subcategory threats, for all 1,795 threatened terrestrial and aquatic threatened taxa. This compilation produced 4,877 unique taxon-threat-impact combinations with the most frequently listed threats being Habitat loss, fragmentation, and degradation (n = 1,210 taxa), and Invasive species and disease (n = 966 taxa). Yet when only high-impact threats or medium-impact threats are considered, Invasive species and disease become the most prevalent threats. This dataset provides critical information for conservation action planning, national legislation and policy, and prioritizing investments in threatened species management and recovery.

Keywords: Australian threatened species; EPBC Act; IUCN Threat Classification Scheme; IUCN Threat Impact Scoring System; Threat impacts; Threatened species.

FIGURE 1

Proportion of Australian threatened taxa impacted by broad‐level threats. Each bar chart represents a different group, including plants, invertebrates, fish, frogs, reptiles, birds, and mammals. Threats including Habitat loss, fragmentation, and degradation (dark blue), Invasive species and disease (indigo), Adverse fire regimes (purple), Disrupted ecosystem and population processes (magenta), Overexploitation and other direct harm from human activities (coral), Changed surface and groundwater regimes (orange), Climate change and severe weather (gold), and Pollution (yellow)

FIGURE 2

Number of threatened Australian taxa and relative level of impact for each subcategory threat, nested within the corresponding broad‐level threat class. See Table 2 for symbols representing each broad‐level threat. Relative levels of impact are color‐coded as dark purple (high impact), maroon (medium impact), tangarine (low impact), bronze (negligible impact), and teal (insufficient data). The scale bar indicates the cumulative number of taxa impacted per threat

FIGURE 3

The most important threats to threatened Australian taxa change when impact is considered. The diagrams show the number of taxa per impact score within the broad‐level threat (a) Habitat loss, fragmentation, and degradation, (b) Invasive species and diseases, (c) Adverse fire regimes, and (d) Climate change and severe weather. Impact was determined through the evaluation of timing, severity, and scope for each threat per taxon. Where a taxon was threatened by multiple subcategories within a broad threat, we used the maximum impacting level in this analysis. For example, if a taxon was assessed as being threatened by Residential and commercial development at a low impact and Agriculture and aquaculture at a high impact under the IUCN classification scheme, which both fall under the broad‐level threat of Habitat loss, fragmentation, and degradation, the broad‐level threat was considered high impact for that taxa