Trigwell's Rulingia (Rulingis sp. Trigwell Bridge) 2003-2008

Interim recovery plan no. 148
Gillian Stack and Andrew Brown
Department of Conservation and Land Management, WA, 2003

Summary

Scientific Name: Rulingia sp. Trigwell Bridge Common Name: Trigwell's Rulingia
Family: Sterculiaceae Flowering Period: August
Dept Region: South West Dept District: Wellington
Shire: West Arthur Recovery Team: South West Region Threatened Flora Recovery Team (SWRTFRT)

Illustrations and/or further information: A. Brown, C. Thomson-Dans and N. Marchant (Eds) (1998) Western Australia's Threatened Flora; N.G. Marchant, J.R. Wheeler, B.L. Rye, E.M. Bennett, N.S. Lander, and T.D. Macfarlane (1987) Flora of the Perth Region; The Department (1998) FloraBase - Information on the Western Australian Flora (http://www.calm.wa.gov.au/science/).

Current status: Rulingia sp. Trigwell Bridge was declared as Rare Flora in November 1993 and ranked as Critically Endangered (CR) in 1995. It currently meets World Conservation Union (IUCN, 2000) Red List Category 'CR' under criteria A1c; B1ab(iii)+2ab(iii); C2a(i); D as there has been an estimated population size reduction of 90%; the extent of occurrence is estimated to be less than 100 km2 and the area of occupancy less than 10 km2; the species is known to exist at a single wild location with a continuing decline in the quality of habitat and the single known population contains fewer than 50 mature individuals in size.

Rulingia sp. Trigwell Bridge is known from a single very small wild population of two adult plants with a continuing decline in the quality of its habitat. There are also four translocated populations. The species appears to have very specific habitat requirements and its restricted distribution is a major threat to its survival. Other threats include the lack of natural recruitment, poor genetic diversity, inappropriate fire regimes, grazing and weeds.

Distribution and habitat: Rulingia sp. Trigwell Bridge is endemic to Western Australia where it is known from a single wild population in the West Arthur area over a range of less than 1 km. Plants are found in small fissures on a lateritic ridge supporting open low jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) woodland. It is not known whether this is the plant's preferred habitat or if these plants have survived because they were less accessible to grazing animals. Associated species include Banksia grandis, Xanthorrhoea preissii, Macrozamia riedlei, Sollya heterophylla and Acacia pulchella (Brown et al. 1998).

Critical habitat: The critical habitat for Rulingia sp. Trigwell Bridge comprises the area of occupancy of the known populations; area of occupancy of translocated populations; similar habitat within 200 metres of known and translocated populations; corridors of remnant vegetation that link populations and additional nearby occurrences of similar habitat that do not currently contain the species but may have done so and may be suitable for additional translocations.

Habitat critical to the survival of the subspecies, and important populations: Given that this species is listed as Critically Endangered it is considered that all known habitat containing wild and translocated populations is habitat critical and that all populations are important.

Benefits to other species/ecological communities: Recovery actions implemented to improve the quality or security of the habitat of Rulingia sp. Trigwell Bridge will also improve the health of the habitat in which it occurs.

International obligations: This plan is fully consistent with the aims and recommendations of the Convention on Biological Diversity, ratified by Australia in June 1993, and will assist in implementing Australia's responsibilities under that Convention. However, as Rulingia sp. Trigwell Bridge is not listed under any international agreement, the implementation of other international environmental responsibilities is not affected by this plan.

Role and interests of indigenous people: There are no known indigenous communities interested or involved in the management of areas affected by this plan.

Social and economic impacts: The implementation of this recovery plan is unlikely to cause significant adverse social and economic impacts. The single known wild population occurs on private property and has been fenced with the approval of the owners.

Evaluation of the Plan's Performance: The Department of Conservation and Land Management (DCLM), in conjunction with the Recovery Team will evaluate the performance of this IRP. The plan is to be reviewed within five years of its implementation.

Existing Recovery Actions: The following recovery actions have been or are currently being implemented -

  1. Land owners have been made aware of the location and threatened status of the species.
  2. A ringlock fence was erected in 1992 to exclude sheep from Population 1.
  3. A netting cage was erected in 1994 to exclude rabbits and 'twenty eight' parrots from Population 1.
  4. Botanic Garden and Park Authority (BGPA) staff conducted germination trials in April 1995.
  5. In 1995 samples taken to assess the presence of Phytophthora cinnamomi (dieback) in the habitat tested negative. Dieback hygiene practices are adhered to.
  6. Tests undertaken by the Department's Science Division staff indicate that the species is not susceptible to dieback.
  7. Soil sample analyses have indicated high organic matter and average nutrient levels at Population 1.
  8. Soil sample analyses have indicated very high organic content at Population 1, probably due to deep fissures in rock collecting leaf debris. The plants grow in these deep fissures.
  9. In 1997 BGPA staff conducted experimental micropropagation trials to establish long-term cryostorage of the species.
  10. The Department's Threatened Flora Seed Centre (TFSC) has over 7,000 seeds in long-term storage.
  11. The Botanic Garden and Parks Authority currently have 75 plants of Rulingia sp. Trigwell Bridge from five clones.
  12. Translocations have taken place according to an approved Translocation Proposal.
  13. All translocation areas have been fenced.
  14. Grazing by rabbits within fenced areas at Populations 1 and 2 has been controlled with use of 1080 oats.
  15. An information sheet that describes and illustrates the species has been produced.
  16. Staff from the Department's South West Region regularly monitor both natural and translocated populations of the species.
  17. 17. The South West Region Threatened Flora Recovery Team is overseeing the implementation of this IRP and will include information on progress in an annual report to the Department's Corporate Executive and funding bodies.

IRP Objective: The objective of this Interim Recovery Plan is to abate identified threats and maintain or enhance in situ populations to ensure the long-term preservation of the species in the wild.

Recovery criteria
Criteria for success: The number of individuals within populations and/or the number of populations have increased by 10% or more.
Criteria for failure: The number of individuals within populations and/or the number of populations have decreased by 10% or more.

Recovery actions
1. Coordinate recovery actions 8. Conduct further surveys
2. Develop and implement a fire management strategy 9. Collect seed and cutting material
3. Control grazing 10. Continue implementing translocations
4. Undertake weed control 11. Obtain biological and ecological information
5. Maintain dieback hygiene 12. Promote community awareness
6. Monitor populations 13. Review this IRP and revise it or prepare a full Recovery Plan if necessary
7. Liaise with land managers