Document ID: chunk:federal_register_of_legislation:F2025L00287:reg:3:p202
Version: federal_register_of_legislation:F2025L00287
Segment Type: reg
Provision Reference: reg 3 (pt 202/276)
Character Range: 744277–748049

growing to 1m but sometimes to 3m tall with olive green flowers.

Distribution and abundance
There were 38 mature individuals of Euphorbia norfolkiana known in 2003 (TSSC 2003a). A 2007 survey found a total of 104 plants on Norfolk Island, of which 42 plants were higher than 1m tall, including 12 plants in Bumbora Reserve and 5 plants in Ball Bay Reserve; most plants were on private land near Bumbora Reserve (Mills 2007d). In 2012 the species was decreasing in abundance, with only one small plant found in Bumbora Reserve, and 13 individuals counted on a transect in the valley east of Cook's Monument in Norfolk Island National Park (Mills 2012b).
By 2021 the population had increased to 388, including 25 in Bumbora Reserve (planted in 2017) and 29 at Ball Bay Reserve (wild population) (Mills 2017a, b). The species has also been planted on Phillip Island (Mills 2009b).

Ecology
This species can establish on bare, loose soil but may need partial shade for the most effective establishment. Most plants establish below an open cover of pine.

Habitat
Occurs in in coastal pine and white oak forest (Invasive Species Council & TierraMar 2021), in open areas in light shade amidst coastal cliff vegetation, usually below pines.

Threats
Threats to the species include small population size and restricted distribution and subsequent increased risk of extinction through natural events such as cyclones, slips and drought; weed invasion and competition from weeds such as African olive (Olea europaea cuspidata) and kikuyu (Cenchrus clandestinus); and cattle grazing. Phytophthora cinnamomi is potentially a major risk.

Impact on other species
None known.
Map 37 Distribution of Euphorbia norfolkiana
Green outlines indicate reserves within which the species occurs. Green shading shows plant communities within which the species may occur (Christian & Mills 2021). Points show recorded locations (Mills 2017a, b).

Risk assessment
Risk assessment undertaken for Critically Endangered trees/shrubs as a grouping. The risk assessment is shown in Table 91.
Table 91 Risk assessment for Critically Endangered trees/shrubs 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                                                                                            Almost certain (91–100%)  Major        Extreme
7. Predation by cats                                                                                               Rare (0–10%)              Negligible   Negligible
8. Predation or damage by chickens                                                                                 Likely (51–90%)           Moderate     Medium
9. Predation by swamphens                                                                                          Rare (0–10%)              Negligible   Negligible
10. Predation by Argentine ant                                                                                     Possible (26–50%)         Minor        Low
11.