Prasophyllum sp. 'Moama' - critically endangered listing
The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the orchid Prasophyllum sp. ‘Moama’ (D.L. Jones 19276) as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act. Listing of critically endangered species is provided for by Part 2 of the Act.
NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Prasophyllum sp . ‘ Moama’ ( D.L. Jones 19276) of the family Orchidaceae is a terrestrial herb of the Leek Orchid genus. It has a single erect tubular tapering leek-like leaf, up to about 30 cm tall and about 2-3 mm diameter, through which the inflorescence spike breaks, leaving a free segment of leaf above. The fragrant flowers, borne in September and October, are not densely crowded on the spike, are usually predominantly reddish-brown with greenish tints; the lateral sepals are semi-connate or free, more or less parallel; the dorsal sepal is up to 10 mm long; the labellum is reddish and narrow with flat non-crinkled margins, the callus plate is raised, green, and non-glossy. As with many undescribed Prasophyllum species, expert assistance is advisable when making identifications. Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) is similar to P. occidentale R.S. Rogers but the latter differs in having predominantly pale yellowish green flowers, the lateral sepals always free, a glossy callus, and the labellum margins crinkled. It is also similar to P. suaveolens D.L. Jones & R.J. Bates, but that species differs in having smaller green to yellow-green flowers with only limited red or pink markings, the lateral sepals free or fused only at the base, a glossy callus, a forward-projecting labellum which is strongly deflexed in the distal third, the labellum margin smooth or only slightly irregular and a later (October-November) flowering time. [Descriptive and diagnostic data based on Jeanes and Backhouse 2001; Jones 2006; Rouse 2002; McDougall in litt. 2006. Illustrations are available in Rouse (2002: pl. 61a, 61b), and Jeanes and Backhouse (2000, 2001 – both as P. sp. aff. suaveolens, Hunter Leek Orchid). Rouse (2002) also cites, as being of this species, an illustration in Backhouse and Jeanes (1995: 251) of ‘ P. suaveolens’ from ‘Kamerooka area’ near Hunter, Victoria.]
2. The species has also been informally named (Jeanes and Backhouse 2000, 2001) as ‘P. sp. aff. suaveolens Hunter’ (referring to a Victorian locality). The common name ‘Hunter Leek Orchid’ has been applied to the Victorian populations, (e.g. Jeanes and Backhouse 2000, 2001; DSE 2005). It is likely that this common name, if taken up in NSW, would cause some confusion as it would tend to be assumed to refer to a taxon occurring in the Hunter Valley region of NSW. Accordingly it is noted but not recommended for NSW use.
3. Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) is listed (as ‘ Prasophyllum aff. occidentale D’) as Endangered on the Advisory List of Rare Or Threatened Plants In Victoria (DSE 2005). It is coded as endangered in Victoria and nationally in Ross and Walsh 2003 (as ‘ Prasophyllum aff. occidentale D sensu Rouse’). It is not legislatively listed under the Victorian Flora and Fauna Guarantee Act (1988).
4. Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) is known in NSW from only one locality, discovered in 2005, near Moama. The site is in the Murray Local Government Area, and the Riverina Bioregion of Thackway and Cresswell (1995). Several previous surveys of Riverina grassland and regional Travelling Stock Reserves in New South Wales (including McDougall et al. 1993, Benson et al. 1997, Webster 1999, and McNellie et al. 2005) did not detect the species. The species is not endemic to New South Wales, occurring also in Victoria in small to moderate-sized populations within 50 km around Echuca (Rouse 2002).
5. Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) is not known to occur in any conservation reserves in New South Wales. The Moama site is currently managed, under short-term funding, as a high conservation value area on a Travelling Stock Reserve (TSR), but remains subject to discretionary grazing.
6. The population near Moama has been variously estimated as comprising several hundred to 1,000 plants (K. McDougall in litt. 2006, based on 2005 observations), or “closer to 10,000” plants (D. Jones pers. comm. 2007, based on 2006 observations). Estimation of numbers can be difficult as Prasophyllum species die back annually to a tuber (Backhouse and Jeanes 1995), and may exhibit great variation in vegetative sprouting and especially in flowering from year to year, probably in response to rains in the previous winter and/or fires in the previous summer (Bishop 2000, Jones 2006). The population extends over an area of about 20 hectares of fairly uniform but uncommon habitat (K. McDougall in litt. 2006).
7. The New South Wales population is reported (K. McDougall in litt.) as occurring in “forb-rich grassland on flat alluvial plains …The grassland appears to be natural and not derived from Acacia pendula woodland”. The only tree species recorded as present nearby is Allocasuarina luehmannii (Buloke, Bulloak). The soil is a reddish, probably calcareous clay-loam (K. McDougall and N. Walsh, pers. comms. May 2007). The species is recorded as growing in broadly similar sites in Victoria (Jeanes and Backhouse 2001, Rouse 2002).
8. McDougall (1993) assigns the grass/herb community at the Moama site to a ‘Community R1.1’, also occurring in Victoria and which may manifest as “tussock grassland, herbfield or low chenopod shrubland (possibly disclimax). May be dominated by one of many species but most frequently Danthonia setacea (pilose form)”. The community is described as occurring in calcareous clay loams on plains of Quaternary alluvial sediments, with an annual rainfall of 405-465 mm. The orchid habitat at the Moama site has been mapped (DIPNR 2004) as part of unit ALP30 ‘Grasslands with scattered trees on alluvial plains’. McNellie et al. (2005) recorded the primary floristic group (including the orchid site) within this map unit as ‘Low Grasslands and/or Forblands with scattered stands of Eucalyptus microcarpa or Eucalyptus largiflorens or Allocasuarina luehmannii’, “consisting of numerous small (approximately 10 to 30 ha) and isolated and discontinuous patches within the cropping zone of the southern Riverina”.
9. Wasps, bees, syrphiid flies and a variety of other flying invertebrates are recorded as pollinators for the genus Prasophyllum (Bishop 2000, Jones 2006), although some instances of self-pollinating species are known (Jones 2006). No pollination syndrome has been determined for Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) but it is known to produce scented flowers and is probably insect-pollinated. Flowering of the Moama species has been recorded in September and October (Jeanes and Backhouse 2001, Rouse 2002), although flowering rates may be strongly affected by presence or absence of fires and rains in preceding seasons. Like most Australian terrestrial orchids the species is believed to be semi- or fully obligately dependent on a mycorrhizal symbiont.
10. Natural grassland communities in the Riverina area of NSW and Victoria have undergone significant declines since the advent of European settlement and stock-grazing. McDougall et al. (1993) report high levels of decline of this general vegetation type. However, past decline of the specific habitat in which this Prasophyllum occurs in New South Wales cannot be confidently inferred as yet. It has been suggested (Benson et al. 1997:13, apropos a region to the north of the Moama site) that post-settlement declines of natural grassland communities may have been less severe on the NSW side of the border. Nevertheless, the assignment of the Moama grass/forb community to a distinct vegetation type (McDougall et al. 1993, DIPNR 2004, McNellie et al. 2005), that is rare and restricted in NSW, but shared with at least one occurrence of the same Prasophyllum species in Victoria (Terrick Terrick – K. McDougall pers. comm. May 2007), suggests that the Moama population may be best regarded as a naturally isolated occurrence within NSW. This interpretation may be supported by the co-occurrence of Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) and another rare orchid, Pterostylis despectans, at both the Moama site and at Terrick Terrick (Vic.), in both cases within habitat assignable to ‘Community R1.1’ of McDougall et al. (1993).
11. Prasophyllum sp. ‘ Moama’ ( D.L. Jones 19276) at the Moama site appears to be strongly dependent for maintenance of its numbers and habitat on the maintenance of suitable site management practices. The site has been heavily grazed at times in the past (K. McDougall in litt. 2006, citing pers. comm. from M. Mullins, Deniliquin Rural Lands Protection Board), but the lack of a nearby stock watering point has probably kept trampling and grazing damage down and contributed to the highly diverse floristic condition of the site (K. McDougall in litt. 2006). Recently the high conservation value of the site, based on its floristic diversity, has been recognised and a management regime that limits grazing of the site is in place under short-term funding. It is likely that some grazing may be beneficial for the native vegetation of the site. Conversely it is probable that too heavy a stock presence, particularly after rain or resulting from construction of a watering point, would have negative effects on both the orchid and its habitat.
12. Annual exotic grasses and Romulea spp. are reported as encroaching on the orchid habitat, mainly from disturbed soil in or adjacent to a road table drain and from an easement on the site (K. McDougall in litt. 2006, pers. comm. 2007). The highest risk of sudden spread of these weed species within the site probably lies in a coincidence of a rain event with heavy grazing and trampling by cattle, leading to intensive soil disturbance over a wider area. Some light stock grazing in drier periods and appropriate seasons may help to control these weeds. A decline in abundance and habitat quality is likely in the NSW population.
13. Prasophyllum sp. ‘ Moama’ (D.L. Jones 19276) is eligible to be listed as a Critically Endangered Species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:
Clause 15
The geographic distribution of the species is estimated or inferred to be:
(a) very highly restricted,
and:
(d) a projected or continuing decline is observed, estimated or inferred in:
(i) an index of abundance appropriate to the taxon,
(ii) geographic distribution, habitat quality or diversity, or genetic diversity;
(e) the following conditions apply:
(i) the population or habitat is observed or inferred to be severely fragmented,
(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations.
Professor Lesley Hughes
Chairperson
Scientific Committee
Proposed Gazettal date: 31/08/08
Exhibition period: 26/12/08
References:
Backhouse GN, Jeanes JA (1995) ‘The orchids of Victoria.’ (The Meigunyah Press, Melbourne).
Benson J, Allen CB, Togher C, Lemmon J (2006) New South Wales Vegetation Classification and Assessment: Part 1, Plant communities of the NSW Western Plains. Cunninghamia 9, 383-450.
Benson JS, Ashby EM, Porteners MF (1997) The native grasslands of the Riverine Plain, New South Wales. Cunninghamia 5, 1-48.
Bishop A (2000) ‘Field guide to the orchids of New South Wales and Victoria’. (University of New South Wales Press, Sydney).
DIPNR (2004) ‘Echuca – 7825, edition 1.’ [Native Vegetation Map]. Dept of Infrastructure, Planning and Natural Resources, Wagga Wagga NSW.
DSE (2005) Advisory List of Rare Or Threatened Plants In Victoria – 2005. Victorian Department of Sustainability and Environment, East Melbourne, Victoria.
Jeanes JA, Backhouse GN (2000). 'Wild Orchids of Victoria, Australia.' (CD-ROM, Zoonetics, Seaford, Vic.)
Jeanes JA, Backhouse GN (2001). 'Wild Orchids of Victoria, Australia.' (Zoonetics, Seaford, Vic.) [Revised book version of Jeanes and Backhouse 2000].
Jones DL (2006) ‘A complete guide to native orchids of Australia, including the island territories.’ (Reed New Holland, Frenchs Forest NSW).
McDougall KL, Barlow T, Appleby M (1993) Grassland communities and significant grassland sites: Western Basalt Plains, Lake Omeo, Murray Valley Riverine Plains and the Wimmera. In: ‘Conservation of lowland native grasslands in south-eastern Australia’. (Eds KL McDougall and JB Kirkpatrick). World Wide Fund for Nature: Australia.
McNellie M, Greenwood G, Vanzella B, Horner G, Schliebs M, Turner B, Davy MC, Hudspith TJ, Nott TA (2005). Native vegetation map report series No. 5 Moulamein, Wanganella, Conargo, Cohuna, Mathoura, Tuppal and Echuca 1:100 000 Map Series. Unpublished report, Department of Infrastructure, Planning and Natural Resources, Wagga Wagga.
Ross JH, Walsh NG (2003) ‘A Census of the Vascular Plants of Victoria Edn 7.’(Royal Botanic Gardens, Melbourne) (web version accessed 29 May 2007).
Rouse DT (2002) ‘Report on the taxonomic, ecological and conservation status of taxa in the genus Prasophyllum R.Br. in south-eastern Australia’. [unpublished report].
Rouse DT (2005) ‘Prasophyllum update’. [unpublished email circular].
Thackway R, Cresswell ID (1995) ‘An interim biogeographic regionalisation for Australia. Version 4.0’. Australian Nature Conservation Agency, Canberra.
Webster R (1999) Flora and fauna habitat assessment of Travelling Stock Reserves within the Murray Rural Lands Protection Board. Unpublished report to Murray RLPB by Ecosystems Pty Ltd, Deniliquin.