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White Beauty Spider Orchid (Caladenia argocalla) Recovery Plan

M.A. Robertson and D. Bickerton
Threatened Species Network, Threatened Plant Action Group
January 2000

Note: This publication has been superseded by the Recovery Plan for Twelve Threatened Orchids in the Lofty Block Region of South Australia 2010

1.0 Summary

1.1 Current species status

Caladenia argocalla (white beauty spider-orchid) is listed as nationally Endangered on Schedule 1 of the Commonwealth Endangered Species Protection Act 1991 and as Endangered 2ECiby Briggs and Leigh (1996). C. argocalla is endemic to South Australia, where it is confined to the Mount Lofty Ranges (Figure 1). Less than 500 mature plants of C. argocalla are known, in six sub-populations (Figure 1). Apart from two sub-populations consisting of one or a few plants the species' distribution is confined to 10 square kilometres near Clare, in the Mid-North of SA. Records in the State Herbarium (Plant Biodiversity Centre) indicate that the species' former range was approximately 200 km from north to south along the ranges. According to the IUCN criteria B1 and B2(a) (IUCN, 1994) C. argocalla is Endangered because its extent of occurrence is less than 5000km2, its area of occupancy is less than 500km2, it is extant at only five known locations and it has a projected continuing decline in extent of occurrence and number of populations.

1.2 Habitat requirements and limiting factors

The three largest surviving populations of Caladenia argocalla occur in intact grassy woodland communities near Clare, SA. Such vegetation has been selectively cleared in the past, particularly in this region, because it is situated on soils that are suitable for agriculture with favourable rainfall. Fragmented remnants of these habitats are also vulnerable to invasion by alien plant species. The species has become extinct from locations where woodland habitat has become degraded in the past 15 years. Continuing decline in quality of habitat is probable without intensive management because the larger populations are threatened by alien plant invasion.

1.3 Overall recovery objectives

  1. Long term: to increase the probability of survival of Caladenia argocalla across its range.
  2. Medium Term: to prevent decline in area of occupancy, quality of habitat and abundance of C. argocalla in the next five years.

1.4 Specific objectives

  1. Maintain or increase the area of occupancy of the species
  2. Minimise the loss of genetic variability across the species range
  3. Maintain the extent of occurrence of the species
  4. Maintain or increase the abundance of the species.

1.5 Recovery criteria

  1. Extent of occurrence is maintained in the next five years
  2. Populations that currently have less than 5 mature plants are protected from extrinsic threats within one year and increased in size by at least 50 % within five years.
  3. The number of mature plants at the main populations (more than 100 mature plants) is maintained or increased in the next five years
  4. Area of occupancy of the main populations is maintained or increased in the next five years
  5. Seed from all known populations greater than one plant is collected and stored within one year to minimise the loss of genetic variability
  6. Available area of quality habitat at the Windermere location increased by 20% within 5 years.

1.6 Actions needed

  1. Abate threats to larger populations
    1. Management plans for sub-populations on council managed and private lands
    2. Ongoing weed control at all the Clare Hills locations
    3. Herbivory control trials in Spring Gully Conservation Park and Hughes Park Road
  2. Abate threats to very small populations through herbivory control (tree guards or netting at Mt Beevor and Kaiser Stuhl)
  3. Collect and store seed from known populations to minimise loss of genetic variability
  4. Increase abundance:
    1. Hand pollination for very small populations (Mt Beevor and Kaiser Stuhl)
    2. Pollination trials for larger populations (Spring Gully and Hughes Park Road)
  5. Search for additional populations
    1. Document habitat at Mt Beevor
    2. Search for new populations (Clare Hills, Barossa Valley, Fleurieu Peninsula, eastern ranges)
  6. Monitor all known sites
  7. Manage the project through the Recovery Team

1.7 Biodiversity benefits

The preferred habitat of Caladenia argocalla is open grassy woodland on relatively fertile soil, a habitat that is greatly depleted, fragmented and threatened in South Australia, with few large examples surviving in good condition. The values of such remnants have not been widely appreciated and they are under threat from incremental roadside and urban clearance, grazing and tree planting programs. Involving the community in conserving this species will increase awareness of the biodiversity of grassy woodlands, their threatened status and management needs. It will foster an appreciation of the importance of intact habitats to support populations of invertebrates that pollinate native orchids such as C. argocalla.

1.8 Estimated cost of recovery

Year Action Total
1.1 1.2 1.3 2 3 4.1 4.2 5.1 5.2 6 7
2000 4.7 1.6 1.3 0.5 0.3 0.3 - 0.1 0.2 1.4 2.6 13.0
2001 - 1.6 1.0 0.4 0.3 0.2 - - 0.2 1.4 2.6 7.9
2002 - 1.6 1.0 0.4 0.3 0.2 0.3 - 0.2 1.4 2.6 8.2
2003 - 1.6 1.0 0.4 0.3 0.2 0.3 - 0.2 1.4 2.6 8.2
2004 - 1.6 1.0 0.4 0.3 0.2 0.3 - 0.2 1.4 2.6 8.2
Total 4.7 8.0 5.3 2.1 1.5 1.1 0.9 0.1 1.0 7.0 13.0 44.7

2.0 Introduction

2.1 Description

The taxon now described as Caladenia argocalla D.L.Jones formerly belonged to the C. patersonii complex of species (Bates & Weber 1990, Jones 1991). The following description of C. argocalla is based on that published by Jones (1991). It is a hirsute, tuberous, terrestrial orchid. The inflorescence is 30-60 cm tall with one or two flowers that are about 9 cm across, white to greenish white with narrow dark central stripes. The solitary leaf is 12-22cm long and 10-18mm wide, hairy with a mixture of two types of hairs. Flower stems are hairy like the leaves. Flowers are not perfumed (unlike C. behrii, which was also included in the former C. patersonii complex) and petals and sepals are long, tapered and curved or drooping with dark red glandular tips. The labellum is white with some dark marginal calli. (C. behriihas a smaller flower and red-tipped labellum.)

2.2 Distribution

Caladenia argocalla is endemic to the Mount Lofty Ranges Region of South Australia (Southern and Northern Lofty Flora Regions). The type collection was from 'Kapunda Hills, Barossa Valley' (at Moppa (Bates pers. comm.)). Historically it has been recorded at a number of locations in and around the Barossa Valley, on the Fleurieu Peninsula, in the hills just south of Adelaide, east at Mt Beevor and north near Clare (Figure 1). The species' former range, based on herbarium collections, was therefore approximately 200 km from north to south.

The species apparently no longer occurs south of Adelaide, where it has not been recorded since 1918. The present north - south range is therefore approx 130 km. The species may be extinct at Moppa near Nuriootpa (last seen in 1986), while populations at Mt Beevor and Kaiser Stuhl CP have declined to fewer than five plants. The only sizeable populations seen in the last decade occurred in Spring Gully Conservation Park and a nearby roadside. In 1999 two previously unrecorded populations were recorded in the Clare Hills: one near Spring Gully Lookout (an extension of the Spring Gully CP location) and the other five kilometres north at Emu Flat. There is anecdotal evidence that locals have known of these populations for decades. Also a single plant was again sighted near Kaiser Stuhl CP.

The species is currently known to exist at five locations. There is a high probability that the species' range will continue to decline due to the very small size of the two populations (Kaiser Stuhl and Mt Beevor) which are now at the southern limit of the species (Figure 1). All known populations of more than 10 plants occur within an area of 10 square kilometres in the Clare Hills.

It is estimated that the former extent of occurrence was approximately 5200 square kilometres and the present extent of occurrence is approximately 1150 square kilometres. The area of occupancy is less than 10 hectares.

2.3 Population size

The total number of mature plants of Caladenia argocalla known in 1999 was 491 in six sub-populations (Table 1). Before 1998 the population in Spring Gully Conservation Park was only known on the western side of the track, in 1998 the known area was extended because plants were found on the eastern side. Extensive further searching within the park in 1998 failed to find any other new patches of C. argocalla and at that time, the Emu Flat population was unknown. There was a report of two flowering individuals from the Mt Beevor site in 1998 (David Davenport, pers. comm.) but the Kaiser Stuhl population was not monitored. The current status of the Mt Beevor population is unknown.

Table 1: The number of flowering C. argocalla sighted in 1998 and 1999
Location Flowering plants
1998 1999
Spring Gully CP (main popn.) 167 128
Spring Gully Lookout - 18
Hughes Park Road 219 269
Private property adjacent Hughes Pk Rd est.20 55
Emu Flat - 20
Near Kaiser Stuhl CP - 1
Total 406 491

Unlike the related Caladenia behrii, in which vegetative plants have greatly outnumbered flowering plants in the 1999 census (Bickerton, unpublished data), few non-flowering C.argocalla leaves were observed at the time of flowering (estimated as one to each three or four flowering plants). This would suggest that most of the total population of C. argocalla is mature plants. However, infertile plants are difficult to detect amongst other herbaceous species in the grassy woodland understorey and may have been missed.

2.4 Habitat

The species occurs in Eucalyptus macrorhyncha - E. leucoxylon (low) woodland in Spring Gully Conservation Park and E. leucoxylon woodland on roadside nearby (Hughes Park Road). The native understorey is predominantly herbaceous at both locations. Dominant understorey species at Spring Gully are wallaby grass (Danthonia spp.) and Poa sp. Co-occurring species are listed in Appendix 1. Slope is moderate at Hughes Park Road and gentle at Spring Gully CP. Soil at the main Spring Gully CP site is a silty clay loam with a high humus and plant root content in the surface layer.

2.5 Life history / ecology

Like other Caladenia species, Caladenia argocalla is believed to live in symbiosis with a mycorrhizal fungus, from which it derives phosphorus (Warcup in Bates & Weber 1990). Mycorrhizae generally invade the embryo or root system of juveniles in the very early stages of development and remain there for the life of the plant. A plant may remain a juvenile for two to five years, producing only a single leaf each spring. Caladenia species are dormant over summer to autumn, storing nutrient reserves in a tuber. A mature plant is believed to have reproductive potential for about 10 years (Bates and Weber 1990). C. argocalla flowers in late September to mid October and if fertilised, it forms a capsule containing large numbers of minute dust-like seed. Caladenias often form replacement tuberoids at a greater soil depth each year (Jones, 1988). It is thought that these tuberoids eventually reach a depth from which leaves and stems cannot reach the surface and the plant dies.

Some Caladenia species flower more profusely after summer fire (Jones 1988). Some indication of the response of C. argocalla to fire could come from an investigation of fire history of Spring Gully and Hughes Park Road sites.

2.6 Pollination

Pollination of C. argocalla by insects has not been documented, but the low level of capsule formation suggests that the breeding system involves cross pollination. Research into pollination in the Caladenia patersonii complex of species was conducted prior to the description of C. argocalla as a species.Since these observations were not made in South Australia they do not apply specifically to C. argocalla but related species may show similar mechanisms. Both sexual mimicry and food deception have been confirmed in the Caladenia genus by Stoutamire (1983) in south-western Australia. However, Adams and Lawson (1993) concluded that there is a lack of firm evidence for pollination of C. patersonii by any particular species or syndrome. Based on Stoutamire's observations they list nectar and pollen eating wasps, hover flies and bees as suggested pollinators of C. patersonii. There is a need for further study of C. argocalla breeding syndrome and pollinating species.

2.7 Reasons for conservation status

In 1998 and 1999 the total flowering population was found to be 406 and 491 plants respectively. The current area of occupancy has been estimated as approximately 10 hectares over about 10 square kilometres. Records indicate that before 1930 the species was much more widespread. The extent of occurrence has apparently decreased (Figure 1) from about 5200 square kilometres to 1150 square kilometres. The population is severely fragmented and occurs at only five locations. There is a projected continuing decline in extent of occurrence and number of locations because the two southern populations are unlikely to be viable. Therefore the species is considered Endangered according to IUCN criteria EB (extent of occurrence less than 5000 square kilometres and area of occupancy less than 500 square kilometres) ENB1 and B2 (a) and (d) (IUCN, 1994).

2.8 Cause of decline

The two largest surviving populations of Caladenia argocalla occur in intact grassy woodland communities. Such vegetation has been selectively cleared throughout the region because it is situated on soils that are suitable for agriculture and grazing. Suitable habitat for C. argocalla is therefore fragmented and modified to varying degrees. Populations are consequently small and fragmented. Invasion by alien plants is the principal result of this habitat modification and reduction in habitat quality for pollinators is also likely to have occurred. This will also impact indirectly on C. argocalla. Habitat of C. argocalla is also likely to have suffered from alteration of the fire regime.

2.9 Current threats

In the long term the species is threatened by small total population size and small size of sub-populations. Flowering plants appear to outnumber non-flowering plants, which may indicate a mature population with little recruitment.

Table 2: The number of monitored C. argocalla flowers that were pollinated and that formed pods in 1999, compared with recent studies of other Caladenia species.
Species C. argocalla C. argocalla C. behrii C. rigida
Site(s) Hughes Pk Rd Spring Gully 25 sites 2 Sites
Year 1999 1999 1998 1996
Sampled Flowers 97 102 1167 329
Pollinated 39 (40%) 2 (2%) 264 (23%) 92 (28%)
Pods 35 (36%) 2 (2%) 166 (14%) 79 (24%)
Reference Bickerton unpublished data Bickerton unpublished data Bickerton (1999) Bickerton (1998)

The 1999 survey found that a high proportion (33%) of plants at the main Spring Gully CP site were either grazed, collected or unaccounted for (Table 3), compared with the Hughes Park Road site. Herbivores may be vertebrate (kangaroos, rabbits) or invertebrate.

Table 3: Herbivory or collection at the two main C. argocalla sites in 1999.
Location Plants Monitored Grazed or Collected Not Found on Final Visit Percentage lost
Hughes Park Road 95 6 2 8%
Spring Gully CP 97 4 28 33%

C. argocallais a large and showy species and therefore under potential threat from collection of either flower stems or whole plants. This is particularly so in Spring Gully Conservation Park where it grows close to a main access track. In such a location it has not yet been possible to discriminate herbivory from collection.

Other potential threats: The Hughes Park Road population occurs mainly on a roadside verge and is potentially under threat from road widening or fence maintenance activities. Increased levels of grazing or minor clearance are potential threats on private land.

3.0 Existing conservation measures

3.1 Land status

Two sub-populations totalling 146 mature plants are conserved within the Spring Gully Conservation Park. The Emu Flat sub-population occurs on a council reserve. The largest sub-population (Hughes Park Road) occurs mainly on road verge and the remaining plants are on private land that is not under any formal conservation agreement.

3.2 Monitoring and survey

The extant populations are being monitored and pollination, capsule formation and herbivory are being monitored in the largest populations. Previous locations in the Barossa Valley area have been visited in the 1980s and 1990s, indicating that some populations have become extinct during the past 20 years (Bates, pers. comm.). Searching in 1998 and 1999 resulted in increased known area of occupancy and number of sub-populations in the Clare Hills.

3.3 Hand pollination

In the belief that low pollination rates were limiting the population size, hand pollination has reportedly been done on occasions since 1988 (NOSSA Journal 1993, Bates pers. comm.) at the Hughes Park Road and Mt Beevor sites. The single plant at Kaiser Stuhl was pollinated by transferring its pollinia to the receptive surface of the stigma in 1999.

3.4 Weeding

Hand weeding of topped lavender has been undertaken occasionally at the Spring Gully CP population since 1993 (Bates pers. comm.) and a systematic program for all woody weeds commenced in 1998 at both Hughes Park Road and Spring Gully populations. All topped lavender has been removed from the populations and this work is ongoing as reinvasion occurs. Temporary control via removal of above ground parts has been undertaken for Cape Tulip.

3.5 Recovery team

A Recovery Team was formed in 1999 to oversee management and recovery of C. argocalla. The team includes representatives of relevant land managers and community groups that are involved in survey, monitoring and recovery activities for C. argocalla.

3.6 Strategy for recovery

Over the next five years the site-specific management strategies will continue to be developed and implemented in collaboration with land managers and community groups. These strategies will be flexible and adaptive as data are collected through the monitoring program. Mature plants of the smallest populations will be individually protected in the short term to try to prevent their imminent extinction and consequent dramatic cut in extent of occurrence and number of populations. Hand weeding to increase abundance and area of occupancy at the larger populations in the Clare Hills will be ongoing. Seed will be collected from populations of more than one plant for cryogenic storage to preserve genetic variability. The Recovery Team will continue to investigate the major factors limiting seed production and recruitment and implement measures to reduce threats over the next ten years. Land managers and community groups will be trained in monitoring and habitat management to ensure that this is ongoing. Where appropriate hand pollination will be conducted to increase seed set.

4.0 Recovery objectives

There is an immediate aim to continue risk management and halt the decline of the larger populations and minimise the likelihood of losing smaller populations. There is also an ongoing objective to find means to increase all populations. The overall objectives are:

  1. Long term: to increase the probability of survival of Caladenia argocalla across its range.
  2. Medium Term: to maintain C. argocalla in the Endangered category in the next five years.

4.1 Specific objectives

The first specific objective is necessary to prevent the species becoming Critically Endangered and the last two are directly related to improving the conservation status of Caladenia argocalla.

  1. Maintain the extent of occurrence of the species
  2. Minimise the loss of genetic variability across the species range
  3. Maintain or increase the abundance of the species.
  4. Maintain or increase the area of occupancy of the species.

5.0 Recovery criteria

For the Recovery Plan to be assessed as successful in reaching its objective, the extent of occurrence should be maintained and the total population of Caladenia argocalla should increase by 20% from (about 500) to 600 within five years and by 50% (to 750 mature plants) within ten years. NB Since the level of recruitment of juveniles and the conditions required for this to occur are unknown and a plant takes two to five years to reach maturity, it is unrealistic to predict major increases in only five years.

5.1 Progress criteria

The following measures will be used to gauge whether the specific objectives have been achieved:

  1. Extent of occurrence (currently 1154 square kilometres) is maintained in the next five years.
  2. All populations are protected from extrinsic threats within one year and the available area of quality habitat at the Hughes Park Road location increased by 20% within 5 years.
  3. The number of mature plants at the main populations (more than 100 mature plants) increased in size by at least 50 % within five years.
  4. Area of occupancy of the main populations is maintained or increased in the next five years.
  5. Seed from all known populations greater than one plant is collected and stored within one year to minimise the loss of genetic variability.

6.0 Recovery actions

To reduce the risk of extinction of Caladenia argocalla, the probability of extinction of the largest populations should be reduced, through protecting their habitats from extrinsic threats (ie. alien plants, clearance), increasing their abundance and area of occupancy. Further monitoring and trials are necessary to assess the importance of low pollination level, herbivory, collecting and habitat change in limiting recruitment in the larger populations. Recovery of C. argocalla will also require immediate action to secure the smallest populations, to maintain the species' extent of occurrence.

The interest and involvement of land managers and local community groups has been established for the main populations, with Friends of Spring Gully as well as the Threatened Plant Action Group undertaking monitoring and weeding in 1998 and 1999. An extension of the known area of occupancy was achieved in 1999 based on local knowledge. These linkages will be established for the southern locations. The Recovery Team is providing linkages and information exchange between various landowners and community groups and local individuals, which may lead to further populations being documented.

6.1 Threat abatement for larger populations

Two of the largest populations (Hughes Park Road and Emu Flat) occur on land that is under the care of the local council, with one of these populations extending onto private land. Management plans are needed to ensure operations such as road maintenance, fence construction and statutory weed control (required by legislation and generally conducted on roadsides using non-selective application techniques) are coordinated with measures underway to recover the orchids and maintain their habitat.

Selective weeding programs have already commenced at the two largest known populations in the Clare Hills. These programs must be continued, as invasion is ongoing. Trials are also needed to assess and abate the threat from herbivory.

6.1.1 Management planning for sub-populations on roadside, council reserve and private land

  1. Liaise with Clare and Gilbert Valleys Council on a management plan for Hughes Park Road and Emu Flat Reserve. Assist council to implement management plans.
  2. Liaise with the landowners adjacent to Hughes Park Road about including the orchids on their land in the recovery program. Assist landowner to seek support for preparing and implementing a management plan including weed control.
Action 1.1 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
4.7 - - - - 4.7

6.1.2 Ongoing weed control

  1. Spring Gully Conservation Park: continue hand weeding of topped lavender from area in park where C. argocalla population occurs.
  2. Hughes Park Road: Hand weeding of woody weed species such as gorse, roses (*Rosa sp.) and hawthorn. Selective chemical control of herbaceous species, particularly Cape Tulip and Soursobs.
  3. Emu Flat Reserve: commence weeding in accordance with management plan.
Action 1.2 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
1.6 1.6 1.6 1.6 1.6 8.0

6.1.3 Herbivory control

Trial protective measures (individual cages) will be established for some plants at Spring Gully CP to determine whether this increases seed production and whether invertebrates or vertebrates are responsible for current levels of herbivory.

Action 1.3 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
1.3 1.0 1.0 1.0 1.0 5.3

6.2 Threat abatement for very small populations

The aim is to remove or reduce the factors that threaten the extinction of the smallest populations of Caladenia argocalla. Two recently recorded populations on private land are extremely isolated and have fewer than five plants and therefore are under imminent threat of extinction due to lack of recruitment, lack of genetic variability, herbivory and other stochastic events.

Herbivory Control: Portable individual mesh cages/tree guards will be installed for the duration of the flowering season surrounding any flowering plants at the Kaiser Stuhl and the Mt Beevor populations.

Action 2 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
0.5 0.4 0.4 0.4 0.4 2.1

6.3 Collect and store seed

To secure the genetic variability of the species, seed will be collected for as many populations as possible and stored at an approved storage site. Orchid seed under optimal storage conditions may remain viable for up to 15 years and can be used to re-establish populations that become extinct, provided mycorrhizal fungi relationships can be re-established. Reintroductions of Caladenias are unlikely to be successful if the local population is extinct because of the difficulty in re-establishing relationships with mycorrhizal fungi. The Recovery Team, in accordance with guidelines and DEHAA approval processes will determine where and under what conditions seed could be collected from wild populations.

The species has become extinct from one confirmed location on private land under Heritage Agreement in the Barossa Valley (Moppa) during the 1980's. This could be a suitable site for reintroduction in the future but will not be considered until there has been a fire in the area or research has been undertaken into the impact of fire or smoke water treatment on the species and its habitat. An appropriate weed and herbivore management regime would need to be instigated first.

Action 3 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
0.3 0.3 0.3 0.3 0.3 1.5

6.4 Increase abundance

If population size is to be increased in the longer term, then pollination and seed set must occur. The two smallest populations are very isolated and opportunities for pollination are limited or absent. Preliminary monitoring of pollination and capsule formation at Spring Gully and Windermere indicate that these processes occurred at very different rates at the two locations. Further monitoring is needed to determine whether lack of successful pollination is the limiting factor at each site. Cooperation of people not participating in the study must be obtained to ensure that no hand pollinating occurs so that the results obtained represent true background pollination levels.

6.4.1 Hand pollination for very small populations.

The populations at Kaiser Stuhl and Mt Beevor will be hand pollinated. Where possible, plants will be cross pollinated, otherwise they will be self pollinated.

Action 4.1 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
0.3 0.3 0.3 0.3 0.3 1.5

6.4.2 Pollination trials at larger populations

If pollination levels are shown to be limiting at Spring Gully and Hughes Park Road in the next two years, the Recovery Team will consider pollinating some plants by hand. All plants pollinated by hand will be tagged and the results monitored.

Action 4.2 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
- - 0.3 0.3 0.3 0.9

6.5 Increase the area of occupancy

There is scope for searching more remnant areas of woodland in the Clare Hills for Caladenia argocalla, including private lands adjoining Spring Gully CP. There is consistency in the habitat type seen at the main extant populations in the Clare region. However, the scarce information that is available from the Barossa Valley area suggests that the species may have occurred in a different type of vegetation there. Many of the historical records of C. argocalla were collected with imprecise, if any, locality details and rarely with any description of habitat. This makes searching for populations in the historical parts of the species' range difficult.

6.5.1 Document habitat

No information is available on the type of habitat occupied by the Mt Beevor population. In order to ensure the survival of this population, and therefore the extent of occurrence of C. argocalla, and to assist in searching for new populations, all known habitats should be described.

Action 5.1- Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
0.1 - - - - 0.1

6.5.2 Search for new populations

Action 5.2 Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
0.2 0.2 0.2 0.2 0.2 1.0

6.6 Monitor all known populations

Populations have been systematically monitored for only one or two years and some populations have only been documented in 1999. Therefore there is a lack of information has been collected on C. argocalla 's reproduction and stability in numbers. At the same time as implementing on ground actions to ensure the survival of the species in the short term, it is necessary to acquire this information on all populations over a number of years. Monitoring should not draw attention to the plants as this species in flower is very showy and at risk from collecting.

It is necessary to monitor populations systematically to gauge the effectiveness of management actions. Data from all surveys and monitoring will be entered into the Threatened Plant Population Database at DEHAA. The following will be monitored:

Action 6 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
1.4 1.4 1.4 1.4 1.4 7.0

6.7 Maintain management of the project through the recovery team

The Recovery Team will take an active role in planning and implementing all actions, and monitor the success of the project. The Recovery Team membership includes Friends of Spring Gully Conservation Park, Native Orchid Society of SA, Threatened Plant Action Group, Clare and Gilbert Valleys Council, National Parks and Wildlife SA and DEHAA Biodiversity Conservation Program. There will be administrative costs involved in running a recovery team and preparing reports, but these will be minimised by holding combined recovery team meetings for several species of threatened orchids occurring in the Lofty Block Bioregion.

Action 7 - Cost Estimate ($'000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
2.6 2.6 2.6 2.6 2.6 13.0

6.8 Upgrade ESAC priority to A

Very little was known of the total population size, number of sub-populations, extent of occurrence and area of occupancy of Caladenia argocalla when the species was first described in 1991. The species has been accorded priority B by the ESAC (date). Data acquired and collated during the first two years of the Lofty Block Orchid Research Plan indicates that the species is one of the State's most endangered orchids. The Endangered Species Advisory Committee should be asked to upgrade the species priority to A.

Implementation schedule

Task Task description Priority Feasibility (%) Responsible party Cost estimate ($000s)
Year 1 Year 2 Year 3 Year 4 Year 5 Total
1.1 Management plans 1 100 TPAG, council 4.7 - - - - 4.7
1.2 Weed control 1 80 FOSG, TPAG 1.6 1.6 1.6 1.6 1.6 8.0
1.3 Herbivory control (SG &W) 2 80 FOSG, TPAG 1.3 1.0 1.0 1.0 1.0 5.3
2 Herbivory control (BH&KS) 1 100 TPAG 0.5 0.4 0.4 0.4 0.4 2.1
3 Seed collection and storage 3 90 TPAG 0.3 0.3 0.3 0.3 0.3 1.5
4.1 Hand pollination small pops 1 60 TPAG 0.3 0.2 0.2 0.2 0.2 1.1
4.2 Hand pollination if required 2 100 TPAG, FOSG - - 0.3 0.3 0.3 0.9
5.1 Document habitat (BH) 2 100 TPAG 0.1 - - - - 0.1
5.2 Search for additional pops 2 80 TPAG 0.2 0.2 0.2 0.2 0.2 1.0
6 Monitor 2 100 FOSG, TPAG 1.4 1.4 1.4 1.4 1.4 7.0
7 Recovery team 3 100 FOSG, TPAG, NOSSA, DEHAA, land managers 2.6 2.6 2.6 2.6 2.6 13.0
Total 13.0 7.9 8.2 8.2 8.2 44.7


The authors wish to thank Bob Bates (NOSSA) and David Jones (Australian National Herbarium) for the useful information and advice they have offered. The assistance given to the authors by Peter Copley, Dr. Adrian Stokes and Roman Urban (DEHAA) in compiling this document is gratefully acknowledged. The support provided by the other members of the Lofty Block Threatened Orchid Recovery Team (Barbara Bayley, Ken Bayley, Stuart Beinke, Erik Dahl, Rick Davies, Professor Hugh Possingham, Tony Sumner, Steve Taylor, Jocelyn Thomas, Rob Veitch, Kerry Ward) is much appreciated.

The Threatened Plant Action Group is a partner in the Lofty Block Threatened Orchid Project, and the advice and support given by various members of the group has been invaluable. Members of the Friends of Spring Gully conservation group kindly donated their time in collecting some of the field data mentioned in this document.


Appendix 1

Plant species recorded at Caladenia argocalla site in Spring Gully Conservation Park

Species in 30m X 30m quadrat Conservation rating
Acacia myrtifolia var. myrtifolia     V
Acacia pycnantha      
Acaena echinata      
* Aira cupaniana      
Arthropodium strictum      
* Avena barbata      
* Briza maxima      
* Briza minor      
Bulbine bulbosa      
Caesia calliantha      
Caladenia argocalla 2ECi E E
Caladenia tensa      
Carex breviculmis     R
Cheilanthes austrotenuifolia      
Cymbonotus preissianus   U R
Danthonia sp.      
Daucus glochidiatus      
Dianella revoluta var. revoluta      
Eucalyptus leucoxylon      
Eucalyptus macrorhyncha ssp. macrorhyncha   R R
Geranium sp.      
Gonocarpus elatus      
Gonocarpus tetragynus      
Gramineae sp.      
Hibbertia exutiacies     U
* Homeria flaccida      
Hydrocotyle laxiflora     U
* Hypericum perforatum      
* Hypochaeris radicata      
Lagenifera huegelii      
* Lavandula stoechas      
Leptorhynchos squamatus      
Lissanthe strigosa     R
Lomandra densiflora      
Lomandra nana     K
Luzula meridionalis      
Microseris lanceolata      
Microtis sp.      
Oxalis perennans      
Pimelea humilis      
Plantago sp.      
Poa sp.      
Pultenaea largiflorens     U
Senecio quadridentatus      
Stackhousia monogyna      
Stipa sp.      
Thelymitra nuda      
Thelymitra sp.      
Thysanotus patersonii      
Wahlenbergia stricta ssp. stricta      
Wurmbea sp.