Hedyscepe canterburyana

The species is threatened by alien introduced Black Rats (Rattus rattus) (Auld et al. 2010, Simmons et al. 2012) that consume fruits and young seedlings. These rats limit recruitment across many sites where the species occurs and Simmons (2012) predicted slow declines, with quasi extinction (population falls below 100) probabilities of up to 0.6–0.8 in the major high altitude sites in the presence of rats. In 2019, rats were eradicated from LHI, although declaration of success of this eradication has yet to be finalized as one incursion of rats occurred in 2021, and was subsequently removed. It will take many years for Hedyuscepe canterburyana to recover from the impacts of these rodents and re-establish juvenile banks of plants and adequate recruitment to replace those adult plants that die and re-invasion by rats remains a threat to the species.

Auld and Leishman (2015) found that a reduction in cloud cover and available moisture is a threat to the summit vegetation of LHI, which includes H. canterburyana. This can impact H. canterburyana in two ways. Firstly, drying climates and droughts (like the recent 2018/19 drought experienced on the island) increase adult mortality and canopy gaps. Secondly, increasing temperatures may reduce the available germination window of the species, limiting recruitment. Both these factors potentially lead to incursions into the habitat of H. canterburyana by species from lower elevations or more exposed areas, as such species are better competitors in warmer and/or drier conditions. Increased frequency and severity of storms can also lead to increased plant mortality.

A large number of exotic weeds occur on LHI and some co-occur with the habitat of H. canterburyana (Pickard 1994). Major threats to the habitat of H. canterburyana are shrubby and climbing species that can readily disperse into, establish and persist in both disturbed and undisturbed habitat and out compete native species. Currently, extensive control work on LHI has limited the spread and reduced infestations of major problem weeds including Cherry Guava, and Asparagus spp. (Lord Howe Island Board 2016, Baker et al. 2018). However, ongoing control of these weeds, leading to eradication, is needed.