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

2. Recovery objective and criteria

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 taxon in the wild.

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.

3. Recovery actions

Existing recovery actions

BGPA have successfully propagated Rulingia sp. Trigwell Bridge using tissue culture, cuttings, and grafting techniques.

The owner of land containing Population 1 has been formally notified of the presence of Rulingia sp. Trigwell Bridge and associated legal responsibilities.

With the permission of the landowner, a ringlock fence was erected around Population 1 in 1992. This excluded sheep from the area which contains the single known population and its lateritic ridge habitat. In 1994 netting cages were erected over all plants of in Rulingia sp. Trigwell Bridge. These cages completely covered plants and protected them from rabbits and 'twenty eight' parrots. The latter had been a major threat to the plants due to their habit of breaking the ends off branches while foraging on the fruit of the species.

In April 1995 staff from the BGPA conducted smoke and smoke water germination trials under and near adult plants at Population with Site 1 (0.9 m x 4.5 m) treated with smoked water (two litres per square metre) and Site 2 (1 m x 5 m) with smoke. Both sites were inspected in October 1995 but no evidence of germination was observed.

The presence of dieback (Phytophthora spp.) was suspected on the northwest slopes of Population 1 in April 1995. However, two samples were sent for analysis and the results were negative and research by staff from the Department's Science Division indicates that Rulingia sp. Trigwell Bridge is not susceptible to this plant pathogen. Disease hygiene is maintained to protect the surrounding habitat.

Soil samples were collected from the wild population in 1995 and sent to the WA Chemistry Centre. Subsequent analysis indicated that the soil is very high in organic content with levels of nitrogen and phosphorus higher than those generally expected in the locality. The higher levels are due to the fact that Rulingia sp. Trigwell Bridge has its roots in deep fissures in which there is an accumulation of leaf litter. Soil samples were collected from the proposed ex situ sites in 1996, for comparison with samples taken from the site of the wild population. The results were consistent with average nutrient levels for most southwestern soils.

During 1997, BGPA undertook research into micropropagation, in vitro physiology, slow growth, germplasm maintenance and cryostorage and had had success in propagation of the species through tissue culture, cuttings and grafting. Propagated plants were transferred into areas of natural habitat successfully.

A total of 608 seeds collected in November 1994 from 4 plants in Population 1 are being stored in the Department's TFSC at -18°C. Seed from this collection had an initial germination rate of 95%. Another 20,000 seeds collected in November 1998 from the wild population and several translocation sites had an initial germination rate ranging from 56 to 85% and, after 12 months storage, a rate of over 90% (unpublished data A. Cochrane ¹). The TFSC now has over 7,000 seeds in long-term storage at -18°C, and over 13,000 seeds stored at 4°C available for direct seeding trials at translocation sites.

The nursery at the BGPA currently have 75 plants of Rulingia sp. Trigwell Bridge from five clones. The species is easy to propagate from cuttings, with a strike rate of 75% and higher (personal communication A. Shade ²).

A translocation proposal that was approved by the Director of Nature Conservation in September 1997 has the aim of establishing self-sustaining populations of Rulingia sp. Trigwell Bridge at up to six locations. In the first year of implementation plants propagated by BGPA were planted into four plots. Plot 1 is adjacent to the only known wild population (Population 1) and Plots 2 and 3 are on a Nature Reserve. A further two translocations were subsequently undertaken - Population 4T in a Nature Reserve and Population 5T in a Conservation Park. Monitoring of translocated plants is ongoing.

In addition to planting nursery grown plants back into the wild, the establishment of additional Rulingia sp. Trigwell Bridge plants has also been attempted by burning areas containing hand sown seed of the species. Experimental burns took place in April 2000. Germination was first recorded in June 2000. Results from this initial trial support the hypothesis that fire stimulates germination of this species and show that a burn with temperatures higher than 50°C and duration of more than ten minutes is required for optimum germination. It is possible that a lack of high intensity fire is a contributing factor to the species' rarity as such fires are quickly put out in agricultural areas. The area of the wild population (Population 1) has not had an intense fire for more than 40 years.

Further burns in areas that were hand sown with Rulingia sp. Trigwell Bridge seed collected for this purpose were undertaken in 2001 and 2002. In 2001 fifty two seeds germinated at one site with eight surviving semi-drought conditions through the 2001/02 summer. Eighteen seedlings germinated at a second site with five surviving the same summer. The 2002 trial burn took place in May over an area of 100m2 in a Conservation Park (Population 5T). Unfortunately weather conditions were not favorable and burning the remainder of the area has been deferred until Autumn 2003. Nevertheless, despite the small size of the area burnt, 223 seeds had germinated by September 2002.

A double-sided information sheet has been produced which includes a description of Rulingia sp. Trigwell Bridge, its habitat, threats, recovery actions and photos. The sheet will be distributed to community members, local libraries and wildflower shows, and also placed on the internet. It is hoped that it may result in the discovery of new populations.

Staff from the Department's South West Region regularly monitor the wild and translocated populations.

The South West Region Threatened Flora Recovery Team (SWRTFRT) is overseeing the implementation of this IRP and will include information on progress in its annual report to the Department's Corporate Executive and funding bodies.

¹ Anne Cochrane, Manager, the Department's Threatened Flora Seed Centre
² Amanda Shade, Horticulturalist, Botanic Garden and Parks Authority

Future recovery actions

Where populations occur on lands other than those managed by the Department, permission has been or will be sought from land owners or managers prior to recovery actions being undertaken.

1. Coordination

The South West Region Threatened Flora Recovery Team (SWRTFRT) will coordinate recovery actions for Rulingia sp. Trigwell Bridge and other Declared Rare flora in the region. The team will include information on progress in their annual report to the Department's Corporate Executive and funding bodies.

Action: Coordinate recovery actions
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $400 per year

2. Fire management strategy

Although it appears likely that the species requires an occasional high intensity fire to germinate soil-stored seed, frequent fires may be detrimental to its long-term survival if young plants have not reached maturity between events. Fire also promotes the introduction and proliferation of weed species. A fire management strategy will be developed by the Department's Wellington District in consultation with relevant land managers and the SWRTFRT.

Action: Develop and implement a fire management strategy
Responsibility: The Department (Wellington District), relevant landholders, Bush Fires Board through the SWRTFRT
Cost: $1,900 in the first year and $600 in subsequent years

3. Grazing control

The two individuals in the natural population (Pop 1) are enclosed in large cages to prevent predation of seed capsules by 'twenty eight' parrots. Translocated plants in Populations 2T and 3T have also been enclosed in cages to prevent grazing. However, rabbits are having a continuing impact on some populations through grazing or digging. It is planned that following consultation with relevant landholders rabbits will be controlled using 1080 oats. Where not already present, fences will be erected to protect Rulingia sp. Trigwell Bridge and its habitat, allowing a suitable buffer area to contain any regenerating plants.

Action: Control grazing
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $6,500 in the first year and $500 in subsequent years

4. Weed control

Some weeds are present at Population 1 but they are not likely to become a major problem due to the exposed rocky nature of the habitat. However, as a precautionary measure, weeds will be hand pulled at that site and weed control maintained at all translocation sites.

Action: Undertake weed control
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $400 per year

5. Dieback hygiene

Although research indicates Rulingia sp. Trigwell Bridge is not susceptible to Phytophthora spp. (dieback), hygiene measures will be maintained to protect the habitat of Population 1 and all translocation sites.

Action: Maintain dieback hygiene
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $300 per year

6. Monitoring

Annual monitoring of threats such as weed invasion, pathogens and predation, and population stability (expansion or decline), pollination activity, seed production, recruitment and longevity is essential.

Action: Monitor populations
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $1,200 per year

7. Liaison

Staff from the Department's Wellington District will continue liaising with relevant land managers and landowners to ensure that populations on private and other non departmental land are not accidentally damaged or destroyed.

Action: Liaise with land managers
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $300 per year

8. Surveys

Surveys supervised by DCLM staff, and with the assistance of community volunteers will be conducted for Rulingia sp. Trigwell Bridge during its flowering period (August).

Action: Conduct further surveys
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $2000 per year

9. Seed and cutting collection

Preservation of germplasm is essential to guard against the possible future extinction of the single known wild population. Such collections can also be used to propagate plants for translocations. Some seed of Rulingia sp. Trigwell Bridge is currently held in the Department's TFSC. However, further collections from as many plants as possible are needed and will be lodged with the TFSC and the BGPA seed store. Cuttings may also be taken and propagated to enhance the living collection at BGPA.

Action: Collect seed and cutting material
Responsibility: The Department (TFSC, Wellington District), BGPA through the SWRTFRT
Cost: $2,400 in first, third and fifth years

10. Translocations

Translocation is essential for the long-term conservation of this species as the single small wild population is threatened by poor genetic diversity (two plants), grazing, a lack of natural recruitement and degraded habitat. Information on the translocation of threatened plants and animals in the wild is provided in the Department's Policy Statement No. 29 Translocation of Threatened Flora and Fauna. This recovery action has started and will continue to be coordinated by the SWRTFRT.

A Translocation Proposal, endorsed by the Department's Director of Nature Conservation, consists of three phases.

  • Phase 1 trialed appropriate establishment techniques to supplement Population 1 and established a population on a conservation reserve with the intention of further supplementation in Phase 2.
  • Phase 2 aimed to establish 5 self-sustaining populations on secure conservation reserves over the 1998-2000 period.
  • Phase 3 includes continued monitoring of all translocated populations, the erection of fences to prevent grazing of seedlings by kangaroos and rabbits, and the establishment of additional translocations to reduce the level of threat to the species.

Phases 1 and 2 have been completed, and Phase 3 has commenced. Monitoring is ongoing for all translocated populations.

Action: Continue implementing translocations
Responsibility: The Department (Wellington District, TFSC), BGPA through SWRTFRT
Cost: $10,000 per year

11. Biology and ecology

Better knowledge of the biology and ecology of Rulingia sp. Trigwell Bridge will provide a scientific basis for management of wild populations. An understanding of the following is necessary for effective management:

  1. The response of Rulingia sp. Trigwell Bridge and its habitat to fire.
  2. The pollination biology of the species and the requirements of pollinators.
  3. The affect and level of invertebrate grazing.
  4. Factors determining level of flower and fruit abortion.
  5. The soil seed bank dynamics of the species and the role of various disturbances (including fire), competition, rainfall and grazing in germination and recruitment.
  6. The longevity of plants and the time taken to reach maturity.

Action: Obtain biological and ecological information
Responsibility: The Department (Science Division, Wellington District) through the SWRTFRT
Cost: $17,200 per year in second, third and fourth years

12. Community awareness

The importance of biodiversity conservation and the need for the long-term protection of wild populations of this species will be promoted to the community through poster displays and the local print and electronic media. Formal links with local naturalist groups and interested individuals will also be encouraged.

Action: Promote community awareness
Responsibility: The Department (Wellington District) through the SWRTFRT
Cost: $2,200 for the first year and $1000 in subsequent years

13. Review this IRP and revise it or prepare a full Recovery Plan if necessary

If the taxon is still ranked as Critically Endangered at the end of the fourth year of the five-year term of this Interim Recovery Plan the need to rewrite this IRP or to replace it with a full Recovery Plan (RP) will be determined.

Action: Review this IRP and revise it or prepare a full Recovery Plan if necessary
Responsibility: The Department (WATSCU, Wellington District) through the SWRTFRT
Cost: $20,300 in the fifth year (if a full Recovery Plan is required)