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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

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National recovery plan for Arachnorchis macroclavia (syn. Caladenia macroclavia) (Large - club Spider - orchid)

Doug Bickerton
National Parks and Wildlife SA
In partnership with Threatened Plant Action Group, February 2003

Note: This publication has been superseded by the Recovery Plan for Twelve Threatened Orchids in the Lofty Block Region of South Australia 2010

Recovery Plan for Arachnorchis macroclavia cover page

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Part B: Planning Components

Note: This publication has been superseded by the Recovery Plan for Twelve Threatened Orchids in the Lofty Block Region of South Australia 2010

Recovery Objectives

In order to remove A. macroclavia from the nationally endangered list, the decline in number of sub-populations and total population size must be halted (IUCN criterion CR B2b) and the individual sub-populations must be increased to a more viable size (IUCN criteria CR C and CR C2a(i)). Since four of the five confirmed extant sub-populations have fewer than ten mature plants, it may not be possible to halt the decline in the number of locations within the five-year term of this plan. For this reason, recovery objectives and criteria are designed for both long-term timelines and the term of the plan.

Overall Recovery Objective

To ensure that A. macroclavia is no longer critically endangered within 20 years (two generations).

Specific Recovery Objectives

  1. Minimize the loss of genetic variability across the species range within five years.
  2. Resolve taxonomic issues relating to outlying herbarium collections within two years.
  3. Maintain or increase the abundance of all sub-populations over the next five years.
  4. Halt or reverse the decline in number of locations over the next five years.

Firstly there is a need to minimize the risk of local extinction of smaller sub-populations and the associated loss of genetic material. Secondly the taxonomic status of spider-orchids at outlying sites needs clarification. Finally the overall population, and all sub-populations, are small and must be maintained or increased to safeguard against extinction.

Performance Criteria

Actions

1. Collect and cryogenically store seed from all known sub-populations.

The Recovery Team will collect seed from all known sub-populations greater than one mature plant. It will be sent to Kings Park and Botanic Gardens WA, for cryogenic storage to maintain viability. Because four of the five sub-populations comprise fewer than 10 mature plants, it may take five years to procure seed from each site.

2. Clarify the taxonomic status of outlying herbarium collections.

When the species was first described(Jones, 1991), some herbarium collections from Eyre Peninsula were considered to be Caladenia macroclavia. Additionally, a collection from Karoonda in 1992 was at first identified as C. macroclavia, and a record in the Threatened Plant Population Database (DEH) claims a sub-population exists in Telowie Gorge CP. Current thought (Bates, pers. comm.) is that all sightings and collections outside of Yorke Peninsula are of species other than Arachnorchis macroclavia. This issue needs to be clarified officially in order to ascertain critical habitat for the species. The Recovery Team will seek advice from taxonomists at Adelaide‘s Plant Biodiversity Centre, and at Canberra‘s Centre for Plant Biodiversity Research. If necessary, experts from the Evolutionary Biology Unit at the South Australian Museum will be asked to conduct allozyme electrophoresis to determine the taxonomy at the outlying sites.

3.1.1 Protect all mature plants with tree guards or wire cages.

Herbivores are present at all sites, and all sub-populations are small, so each flowering A. macroclavia will be given the protection of tree guards or wire cages. The Recovery Team, TPAG, NOSSA, Friends of Agery Reserve and landowners will assist in the placement and maintenance of this protection.

3.1.2.   Implement and continue rabbit control at four sites.

Rabbits are in evidence at Agery, Mona, Muloowurtie and the Pt Vincent property. Only at Muloowurtie are rabbit control measures being used. These controls will continue, and measures will also be implemented at the other sites. The Recovery Team, TPAG, NOSSA, Friends of Agery Reserve and landowners will be responsible for these activities, with the assistance of the Yorke Peninsula Animal and Plant Control Board.

3.1.3. Encourage landowners to place fences around A. macroclavia habitat.

The sub-populations near Pt. Julia and Pt. Vincent are in areas of scrub adjacent to paddocks used for sheep grazing and / or cropping. No fences are in place to prevent the sheep from grazing in the bushland. Also the erection of a rabbit-proof fence at Agery would be beneficial. The Recovery Team will encourage the landholders or managers of all three properties to erect fences, and will inform them of avenues for funding assistance.

3.2. Weed control at Agery, Mona and Muloowurtie.

At Agery, National Trust Officers, volunteers and specialist contractors have used bushcare methods since 1996 to control Bridal Creeper, African Boxthorn, Soursobs and American Aloe. At Muloowurtie, TPAG and APS have worked on Bridal Creeper control since 1996. Weed control will continue at both sites, and will commence at Mona. Members of NOSSA and APS will be encouraged to assist.

3.3.Hand-pollinate flowering plants.

A proportion of flowering plants will be hand-pollinated in order to increase seed set. The number of flowers to be hand-pollinated will be determined by guidelines set by the Recovery Team (Bickerton, 2001[a]). The sites most likely to benefit from hand-pollination are Agery, Muloowurtie and Pt Vincent. All plants will be monitored during the course of the season. Additionally, recruitment will be enhanced by collecting mature seed in October / November, storing it over summer in cool storage at the Adelaide Plant Biodiversity Centre (APBC) and re-dispersing it in late autumn. The Recovery Team and APBC staff will carry out these tasks, with assistance from experienced members of NOSSA and trained volunteers.

4.1. Conduct an annual search for additional sub-populations in areas of critical habitat.

Members of NOSSA and TPAG will be asked to assist in annual searches of critical and potential habitat for previously unrecorded sub-populations of A. macroclavia. Additionally, historical sites and sites with reported but unconfirmed sub-populations (such as Stansbury Scrub) will be searched.

4.2.1. Investigate the potential for translocation if necessary.

In a recent study (Bickerton, 2001[b]) it was deemed not feasible to attempt translocation of Caladenia macroclavia at this stage because:

Should alternative management options be unsuccessful at increasing sub-populations, or should one sub-population become extinct, it may become necessary in the future to re-consider the feasibility of translocation. Primary consideration would be given to the re-stocking of sub-populations nearing extinction, but re-introduction to historic sites would also be contemplated. The Recovery Team would coordinate such actions, with assistance from Plant Biodiversity Centre staff, experienced amateur orchid growers and local volunteers.

4.2.2.   Encourage landowners to place A. macroclavia habitat under conservation agreement.

Two of the five confirmed extant sub-populations are in blocks of remnant vegetation on private property. There is currently no written agreement to secure the long-term conservation of these blocks. The Recovery Team will negotiate with the relevant landowners and expound the benefits of Heritage Agreements or similar conservation covenants.

5. Maintain management of the project through the Recovery Team.

The Recovery Team will continue to meet biennially to plan and implement all actions, and monitor the success of the project. In this way, scientific experts and community representatives can regularly review the progress of the project.

Affected Interests

Table 5: Interests affected by the Recovery Plan's recommended actions; also the manner in which these interests have been or will be addressed.
APBC – Adelaide Plant Biodiversity Centre; CCPBR – Canberra Centre for Plant Biodiversity Research;
DCYP – District Council of Yorke Peninsula; PO – Project Officer; RT – Recovery Team; TSA – Transport SA
ACTION INTEREST(S) AFFECTED MANNER OF ADDRESS
1. Collect and store seed WA Botanic Gardens Liaison with PO
2. Clarify the taxonomic status of outlying herbarium collections. APBC, CCPBR Liaison with PO
3.1.1. Protect mature plants with cages. TSA, DCYP, landowners Liaison with PO
3.1.2. Implement and continue rabbit control at four sites. TSA, DCYP, landowners Liaison with PO
3.1.3. Encourage landowners to place fences around A. macroclavia habitat. Landowners Liaison with PO
3.2. Weed control at Agery, Mona and Muloowurtie. TSA, DCYP. Liaison with PO
3.3. Hand-pollinate flowering plants. - PO
4.1. Search for new sub-populations. TSA, DCYP, landowners Liaison with PO
4.2.1. Investigate the potential for translocation. APBC, amateur orchid growers Liaison with PO
4.2.2. Encourage landowners to place A. macroclavia habitat under conservation agreement. Landowners Liaison with PO
5. Manage the project through the Recovery Team RT members RT meetings