Listing Statement Prasophyllum for Prasophyllum atratum atratum (three hummock leek-orchid)

three hummock leek-orchid

T A S M A N I A N T H R E A T E N E D S P E C I E S L I S T I N G S T A T E M E N T

Image by Matthew Larcombe

Scientific name: Prasophyllum atratum D.L.Jones, Australian Orchid Research 5: 144 (2006) Common Name: three hummock leek-orchid (Wapstra et al. 2005) Group: vascular , , family

Status: Threatened Species Protection Act 1995: endangered Environment Protection and Biodiversity Conservation Act 1999: Critically Endangered

Distribution: Endemic status: Endemic to Tasmanian NRM Region: Cradle Coast

Figure 1. The distribution of Plate 1. Prasophyllum atratum Prasophyllum atratum (Image by Peter Tonelli)

1 Threatened Species Section - Department of Primary Industries, Parks, Water and Environment Listing Statement for Prasophyllum atratum (three hummock leek-orchid)

IDENTIFICATION AND ECOLOGY 5 to 10 cm long. The spike is well-spaced to Species of Prasophyllum are commonly known as moderately crowded with 8 to 25 flowers, 6.5 to leek-orchids because the erect hollow leaf has 7.5 mm long and 5 to 6 mm wide. The flowers some resemblance to that of a leek. Prasophyllum are brownish green to purplish green with a species are terrestrials with small, dark purplish labellum. The flowers open fleshy, round or oval tubers and a few fleshy, widely and are scented. The dorsal is 5 to irregular roots. Most species are dormant over 7 mm long and 3 to 3.5 mm wide. The lateral summer and autumn and begin growth in early are free or fused at the base and are 5.5 winter. The single leaf is reddish at the base as to 7.5 mm long and 1.5 to 2 mm wide. The opposed to green as in onion-orchids (Microtis). are 5 to 7 mm long and 1.2 to 1.5 mm The flower spike emerges through the side of wide, and projected forward to incurved. The the leaf above the middle, with the portion of labellum is sharply recurved near the middle, leaf above the point of emergence being free and is 4.5 to 5.5 mm long and 3 to 4 mm wide. and often withered by the time the flowers The labellum is constricted near the middle and open. The flower spike bears many flowers that tapered with the blackish labellum callus are held upside-down and are often fragrant. extending nearly to the apex of the labellum. The labellum, often with prominent wavy or [description from Jones 2006, Jones & Rouse frilly margins, produces quantities of nectar on 2006] which a wide range of insects feed. Some of these, particularly native bees, wasps and Confusing Species beetles, are effective pollinators. Prasophyllum atratum is allied to Prasophyllum The flowering of many leek-orchids is strongly rostratum (Jones & Rouse 2006) but was dependent on hot summer fires, with large previously included within the Tasmanian numbers of flowering often being concept of Prasophyllum pyriforme (Jones et al. produced a year later but few or none in 1999). Prasophyllum atratum is recognised by the subsequent years. For similar reasons some relatively small, dark coloured flowers, free species may be prominent in disturbed sites lateral sepals (occasionally joined at the base), such as slashed areas, or along track verges and short labellum that is nearly orbicular at the road embankments (Jones et al. 1999). base and with an extended tail-like apex, broad wings with a truncate apex and The flowering of Prasophyllum atratum is likely to pollinarium with a very short or vestigial be enhanced by fire and disturbance because it humulus (Jones & Rouse 2006). is most abundant on the slashed verge of an airstrip and virtually absent from adjacent dense There are several differences between heathland. Prasophyllum atratum and Prasophyllum rostratum, which are described in detail by Jones & Rouse The species can only be identified from flowers (2006), but it is recommended that specialist The type material was collected on 4 November opinion be sought on any collections suspected but the species may flower slightly earlier and it to be Prasophyllum atratum, especially for plants has been identified as late as 5 December so collected in northwestern Tasmania and other late October to mid December is the suggested . survey period (Wapstra et al. 2008). DISTRIBUTION AND HABITAT Description Prasophyllum atratum is known only from the Prasophyllum atratum has a leaf that is erect, type location on the airstrip on Three terete, and 12 to 40 cm long and 3 to 5 mm Hummock in western Bass Strait wide. The base of the leaf is reddish to purple (Table 1, Figure 1). and the upper part dark green. The free part of the leaf blade is suberect, about 8 to 15 cm long Prasophyllum atratum occurs in slashed sedgy and usually partly withered at flowering. The heathland on grey sandy loam beside an airstrip inflorescence is 15 to 30 cm tall with the spike on Three Hummock Island (Plate 2). 2 Threatened Species Section - Department of Primary Industries, Parks, Water and Environment Listing Statement for Prasophyllum atratum (three hummock leek-orchid)

Table 1. Population summary for Prasophyllum atratum.

Subpopulation Tenure NRM 1:25000 Year of Area Number Region * Mapsheet census occupied of mature (ha) plants 1 Airstrip, Three Three Cradle Coast Rochon 1999 0.25 c. 70 Hummock Island Hummock 2006 43 Island State 2008 8.5 c. 500 - Reserve 1000 *NRM region = Natural Resource Management region.

Heathlands comprise only about 1% of the around 240 m south of the airstrip island’s vegetation and are most floristically rich (Department of Primary Industries, Parks, in the slashed areas around the airstrip and in Water and Environment data). the most recently burnt areas (Harris & Balmer 1997, Corbett et al. 2006). According to Corbett It is likely that the species does not regularly et al. (2006), although this habitat type contains emerge on an annual basis, responding only to many components of similar habitat types on events such as slashing and/or fire and it is mainland Tasmania, it does not fit neatly into unlikely to emerge in drought years. Jones & any TASVEG heath community (Harris & Rouse (2006) suggested that the area adjacent Kitchener 2005). Therefore Prasophyllum atratum to the airstrip may contain more plants but occurs in a probably quite unique island habitat. noted that the vegetation had not been burnt or slashed for at least 10 years so is very dense meaning that an extension to the subpopulation is only likely to be detected after a disturbance event. The discovery of an individual on the road that cuts through this surrounding vegetation in 2008 strengthens this argument.

Jones & Rouse (2006) suggested that the species may possibly extend to northwestern parts of Tasmania and but there is no supporting evidence of this. However, the broad vegetation type supporting Prasophyllum atratum is widespread in Tasmania and also well surveyed by orchid enthusiasts and botanists Plate 2. Habitat of Prasophyllum atratum on the because of its tendency to support orchids and airstrip on Three Hummock Island its floristic richness. Although Prasophyllum (Image by Matthew Larcombe) atratum is recently described, there is only a low likelihood of the species having been POPULATION ESTIMATE overlooked in such surveys. Since 1975 Prasophyllum atratum is known from a single Prasophyllum atratum was attributed to subpopulation observed in 1999, 2001, 2002 Prasophyllum pyriforme, a species well known to 2006 and 2008. Approximately 70 plants were local orchid enthusiasts. Therefore given the present in a 0.25 ha area in 1999 and 43 were limited habitat on Three Hummock Island, the counted in 2006 (Department of Primary survey history under the name Prasophyllum Industries, Parks, Water and Environment pyriforme, and the likelihood of specific habitat data). However a survey in November 2008 requirements, it seems unlikely that revealed between 500 and 1000 mature subpopulations of Prasophyllum atratum large individuals over an area of approximately 8.5 enough to influence its conservation status will ha, basically comprising the entire airstrip, and be discovered in the future. an additional single individual beside the road

3 Threatened Species Section - Department of Primary Industries, Parks, Water and Environment Listing Statement for Prasophyllum atratum (three hummock leek-orchid)

RESERVATION STATUS Risks also include not firing at the most Prasophyllum atratum occurs wholly within the appropriate time of year. Hot summer fires are Three Hummock Island Nature Reserve. generally most favourable for leek-orchids for stimulating emergence and flowering (Jones et al. 1999) and provision of recruitment niches. CONSERVATION ASSESSMENT However, such a fire regime is unlikely to be Prasophyllum atratum was listed in 2008 as practical due to safety and infrastructure endangered on schedules of the Tasmanian protection concerns. The more likely repeated Threatened Species Protection Act 1995, at the time spring or autumn burning may lead to the of assessment meeting criterion D because of decline of the subpopulation in the long term. an extremely small total population and very restricted area of occupancy (fewer than 250 The vegetation adjacent to the airstrip has not mature individuals, area of occupancy less than been burnt for about 12 years and it is likely 1 hectare, and occurrence in 5 or fewer that any dormant orchids that may exist in the locations). unburnt vegetation will decline through the atrophy of underground tubers without THREATS, LIMITING FACTORS & appropriate disturbance. It is likely that slashing MANAGEMENT ISSUES alone will be sufficient to allow persistence of Prasophyllum atratum occurs as a highly localised the subpopulation on the airstrip (provided that subpopulation adjacent to an airstrip. Because slashing is not conducted when plants will be of its localised distribution, stochastic events physically damaged on a regular basis), though can lead to extinction. there may be insufficient resources to allow slashing in areas other than those required to Inappropriate burning and slashing regime: maintain the airstrip. Plants may be smothered Long periods without disturbance may lead to if slash is not removed. prolonged dormancy with increased risk of mortality through depletion of stores in Airstrip upgrades and maintenance: underground tubers. Conversely, burning too Activities to upgrade and maintain the airstrip frequently (e.g. annually) can adversely affect on Three hummock Island could be detrimental mycorrhizal fungi communities, rendering the to the species should the requirements of the site unsuitable for the fungal-dependent orchid species not be taken into consideration. In species. Slashing or burning at the wrong time particular, there are frequent proposals to spray of year can damage plants and prevent seed the airstrip to control the build up of moss on from being produced and while the the airstrip. This is likely to be detrimental to subpopulation may be able to sustain such the orchids by directly impacting on the plants damage on occasion, it may not be able to do or their mycorrhizal fungi. so if the damage is regular or in combination Climate change: Changes in the rainfall with other threats such as prolonged drought. pattern may lead to the habitat becoming Regular slashing and associated burning of the unsuitable for the species and associated slash on the airstrip is likely to have been pollinators and mycorrhizal fungi. beneficial to the orchid to date by allowing Stochastic events: While stochastic events are regular emergence and setting of seed. Regular by definition unpredictable, in this case, such slashing and/or ecological burning will be events are most likely to be associated with required to maintain the subpopulation. There airstrip activities. Potential stochastic events is a risk that monitoring and management include plane crashes, fuel spills and localised resources will be insufficient in future years to use of chemicals. maintain an appropriate disturbance regime to allow persistence of the species, both on and off the airstrip.

4 Threatened Species Section - Department of Primary Industries, Parks, Water and Environment Listing Statement for Prasophyllum atratum (three hummock leek-orchid)

MANAGEMENT STRATEGY considered to be Prasophyllum atratum) to be a priority population for recovery actions. What has been done? The airstrip has been upgraded to improve Management objectives safety (by meeting CASA standards), making commercial visitation to the island feasible and The main objective for the management of allow more effective and economically feasible Prasophyllum atratum is to ensure that there is no management of the island by the Parks & decline in the only known subpopulation. Wildlife Service (PWS). Vegetation had reclaimed part of the airstrip and the upgrade What is needed? has involved returning the strip to its original • develop a management plan to specifically dimensions by removing the vegetation through address the ecological requirements of the slashing and burning of the slash. Appropriate Three Hummock Island subpopulation of markers and a wind signalling device have also Prasophyllum atratum (and possibly other been installed. threatened flora species associated with the The upgrade followed discussions between airstrip); PWS, the Threatened Species Section • include requirements of the species in fire (Department of Primary Industries, Parks, management plans for Three Hummock Water and Environment) and an airport Island; consultant, in which site-specific management • provide an appropriate disturbance regime prescriptions were developed. These included to maintain the subpopulation and provide removing moss on the runway by ‘smudging’ recruitment opportunities in nearby areas of (with sectioned tyres chained in sequence) potential habitat, including airstrip rather than by spraying with copper sulphate (as maintenance activities and ecological proposed) as this would be detrimental to burning and/or slashing of surrounding Prasophyllum atratum (and other orchids) by vegetation; killing associated mycorrhizal fungi. • monitor the Three Hummock Island It is intended that the works will increase the subpopulation during the flowering season amount of habitat suitable for persistence and to determine impacts of upgrade and expansion of the orchid subpopulation. As such maintenance activities on the species and to a second (smaller) runway is being restored inform future management; solely to provide additional suitable habitat. • conduct extension surveys of potential Monitoring will be undertaken to gauge the habitat on Three Hummock and other Bass response of the orchid to the works. In Strait islands during the two flowering November 2008, plots were established and seasons following disturbance events; baseline data collected for this monitoring program. • provide information and extension support to relevant Natural Resource Management In November 2008, seed and mycorrhizal fungi committees, local councils, government were collected from the subpopulation for agencies and the local community on the long-term storage at the Tamanian Seed locality, significance and management of Conservation Centre. known subpopulations and potential habitat; Prasophyllum atratum was not formally included • implement the threatened orchid recovery in the Flora Recovery Plan: Threatened Tasmanian plan (TSU 2006) and include the species in Orchids 2006–2010 (TSU 2006), although the any revision of the plan. plan did identify the Three Hummock Island subpopulation of Prasophyllum pyriforme (now

5 Threatened Species Section - Department of Primary Industries, Parks, Water and Environment Listing Statement for Prasophyllum atratum (three hummock leek-orchid)

BIBLIOGRAPHY Prepared in October 2008 under the provisions Corbett, S., Stebbing, M. & Hargraves, F. of the Tasmanian Threatened Species Protection Act (2006). Three Hummock Island Vegetation – 1995. Approved by the Secretary and published Then and Now. Report to the Department of in January 2010. Primary Industries and Water. Cite as: Threatened Species Section (2010). Harris, S. & Balmer, J. (1997). The vegetation Listing Statement for Prasophyllum atratum (three and flora of Three Hummock Island, hummock leek-orchid), Department of Primary western Bass Strait. Papers and Proceedings of Industries, Parks, Water and Environment, the Royal Society of Tasmania 131: 37-49. Tasmania. Harris, S. & Kitchener, A. (2005). From Forest to View: Fjaeldmark: Descriptions of Tasmania’s www.dpipwe.tas.gov.au/threatenedspecieslists Vegetation. Department of Primary Contact details: Threatened Species Section, Industries, Water and Environment, Hobart. Department of Primary Industries, Parks, Jones, D. (2006). A Complete Guide to Native Water and Environment, GPO Box 44, Hobart, Orchids of including the Island Tasmania, Australia, 7001. Phone (03) 6233 Territories. New Holland Publishers 6556; fax (03) 6233 3477. (Australia), Sydney. Permit: It is an offence to collect, disturb, Jones, D.L. & Rouse, D.T. (2006). Fourteen damage or destroy this species unless under new species of Prasophyllum from eastern permit. Australia. Australian Orchid Research 5: 143- 156. Jones, D., Wapstra, H., Tonelli, P. & Harris, S. (1999). The Orchids of Tasmania. Melbourne University Press, Carlton South, . TSU (Threatened Species Unit) (2006). Flora Recovery Plan: Threatened Tasmanian Orchids 2006–2010. Department of Primary Industries and Water, Hobart. Wapstra, M., Roberts, N., Wapstra, H. & Wapstra, A. (2008). Flowering Times of Tasmanian Orchids: A Practical Guide for Field Botanists. Self-published by the authors (April 2008 version). Wapstra, H., Wapstra, A., Wapstra, M. & Gilfedder, L. (2005). The Little Book of Common Names for Tasmanian Plants. Department of Primary Industries, Water and Environment, Hobart.

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