Document ID: chunk:federal_register_of_legislation:F2025L00287:reg:3:p204
Version: federal_register_of_legislation:F2025L00287
Segment Type: reg
Provision Reference: reg 3 (pt 204/276)
Character Range: 750967–755087

Australian National Parks and Wildlife Service, Norfolk Island.
TSSC (Threatened Species Scientific Committee) (2003a) Commonwealth Listing Advice for Norfolk Island Flora – 11 Critically Endangered Species.

Euphorbia obliqua—a herb
Family EUPHORBIACEAE

Conservation significance
Australian distribution restricted to Norfolk Island. Also occurs in New Caledonia and Vanuatu.
EPBC Act Listing Status: Vulnerable.

Description
A prostrate perennial herb with stems to 20cm long.

Distribution and abundance
The natural population of Euphorbia obliqua is mostly found outside of the Norfolk Island National Park; there were 530 mature individuals known in 2003 (TSSC 2003b).
The species has been reported from Emily Bay, Kingston, the rocks near the Old Salt House, and The Chord at Duncombe Bay (Orchard 1994). It is common on Nepean Island, where Mills (2009a) found 154 plants, mainly along the southern shoreline. Mills (2017c) counted 814 in Point Hunter Reserve, the major population of the species on Norfolk Island, and 49 in Kingston Recreation Reserve.
The population estimate in 2021 was 814 individuals.
The distribution is shown in Map 38.

Ecology
Little known.

Habitat
Occurs within sandy beach herbland (Invasive Species Council & TierraMar 2021). Found in calcarenite cracks and fissures in coralline and sometimes basaltic rocks by the sea, with a woody rootstock penetrating the fissures.

Threats
E. obliqua is threatened by small population size and subsequent increased risk of extinction through natural events such as cyclones and drought, specific habitat requirements, and weed invasion and competition.

Impact on other species
None known.
Map 38 Distribution of Euphorbia obliqua
Green outlines indicate reserves within which the species occurs. Green shading shows plant communities within which the species may occur (Mills 2009a). Points show recorded locations (Mills2017c).

Risk assessment
Risk assessment undertaken for Vulnerable herbs/grasses as a grouping. The risk assessment is shown in Table 93.
Table 93 Risk assessment for Vulnerable herbs/grasses as a grouping
Risk                                                                                                               Likelihood of exposure    Consequence  Threat rating
1. Loss and fragmentation of native vegetation through past land clearing                                          Almost certain (91–100%)  Extreme      Extreme
2. Loss and fragmentation of native vegetation through current or future land clearing                             Rare (0–10%)              Negligible   Negligible
3. Degradation of native vegetation through past grazing or loss of nutrients                                      Almost certain (91–100%)  Extreme      Extreme
4. Degradation of native vegetation through current or future grazing                                              Possible (26–50%)         Moderate     Medium
6. Predation by rodents                                                                                            Rare (0–10%)              Negligible   Negligible
7. Predation by cats                                                                                               Rare (0–10%)              Negligible   Negligible
8. Predation or damage by chickens                                                                                 Rare (0–10%)              Negligible   Negligible
9. Predation by swamphens                                                                                          Rare (0–10%)              Negligible   Negligible
10. Predation by Argentine ant                                                                                     Rare (0–10%)              Negligible   Negligible
11. Competition from/change of habitat because of weed invasion                                                    Unlikely (11–25%)         Minor        Low
12. Infection by pathogens already present                                                                         Rare (0–10%)              Negligible   Negligible
13. Impacts of potential new invasive species or