National recovery plan for Tuggeranong Lignum (Muehlenbeckia tuggeranong)
A Recovery Plan under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth), based on an Action Plan (Action Plan No. 24) prepared for the species under the Nature Conservation Act 1980 (ACT).
2. Conservation status
Muehlenbeckia tuggeranong is recognised as a threatened species in the following jurisdictions:
Endangered: Environment Protection and Biodiversity Conservation Act 1999 (Part 13, Division 1, Subdivision A).
Endangered: Section 21 of the Nature Conservation Act 1980, Determination No. 192 of 1998.
Special Protection Status Species: Schedule 6 of the Nature Conservation Act 1980, Determination No. 197 of 1998.
The main threat to survival of this population and therefore the species is likely to be deliberate or unintended actions associated with visitor and/or land management activities in the local area. It is not clear whether grazing animals such as kangaroos may also pose a threat to survival of remaining plants, or whether such grazing may benefit the species by keeping competing grass tussocks and other plant growth short and open.
The objectives of the Recovery Plan are to:
- Preserve the existing ACT population of Muehlenbeckia tuggeranong as it is the only known population of the species.
- Conserve and manage the habitat of Muehlenbeckia tuggeranong so that natural ecological processes continue to operate.
Issues and options for the genetic conservation of M. have been examined by Young (2001). Given the small population and skewed sex ratio, the main genetic conservation issue for the species is the generation of new genetic variation. Young (p. 29) considers that this will be best achieved through controlled pollination among all possible combinations of male and female plants. Such a strategy will maximise the effective population size of the next generation. Seed produced can then be used to increase the size of the current population and equilibrate its sex ratios. They can also be used as a basis for an ex-situ breeding population as well as being outplanted to make new wild populations so as to spread the risk of extinction through habitat loss.
The small number of plants known to exist does not support seed production. Only one female plant has been found, and this has not developed mature ovaries (D.Mallinson pers. comm.). Propagation work undertaken at the Australian National Botanic Gardens has shown that the species strikes extremely well from cuttings, with a success rate around 80%. This could form the basis for ex-situ conservation of the species. Using this clonal material for reintroductions is of little value to genetic conservation given the limited genetic sample, however, ex-situ clone collections can be used to spread the risk of genetic loss due to accidental site disturbance (Young 2001, p. 29).