Diuris ochroma (an orchid) - endangered species listing
The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the orchid Diuris ochroma D. L. Jones as an ENDANGERED SPECIES on Part 1 of Schedule 1 of the Act. Listing of Endangered Species is provided for by Part 2 of the Act.
NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Diuris ochroma D. L. Jones (family Orchidaceae) is an endemic Australian orchid that has been described by Bishop (1996) as: Leaves 3-4, linear, to 30 cm long. Flowering stem to 40 cm, with up to 4 flowers. Flower about 25 mm across, pale yellow with reddish purple striations on both surfaces of dorsal sepal and back of labellum and petals and a cream column. Dorsal sepal ovate with a narrow base, 12 mm long by 8 mm wide, weakly reflexed halfway along. Lateral sepals linear with inrolled margins over most of length, about 16 mm long, rigid, parallel or divergent, pressed against underside of labellum. Petals spreading or incurved, the claw is 7 mm long and the asymmetrically ovate lamina is 8 mm long by 5 mm wide. Labellum directed forwards and downwards, 15 mm long; lateral lobes oblong, toothed at tip, with tiny cilia; midlobe broad-ovate with claw-like base, about 12 mm long by 13 mm wide, flat; margins with tiny cilia towards base of lamina. Callus of 2-4 irregular roughened edges 5-8 mm long, broader and often divided at apex, surrounded by low radiating ridges; keel roughened and ridged at base, reaching to tip of labellum.
2. In NSW, Diuris ochroma is restricted to a single population in the Kybeyan area, Monaro Tableland. Approximately 70 mature individuals were recorded at the site during targeted surveys of the Kybeyan area in December 2003 (Miles & McPherson 2004). Searches of suitable habitat elsewhere in the district failed to locate additional populations of the species.
3. The population occupies about 6 ha of freehold pasture and adjacent road easement at an elevation of 975-1000 metres above sea level. The habitat here comprises grassland and open woodland with few remaining trees on brown loam over shale.
4. Diuris ochroma is also found in Victoria where the species is considered vulnerable (VDSE 2003) and is protected under the Flora and Fauna Guarantee Act 1988. It is also listed as a vulnerable species under the Environment Protection and Biodiversity Conservation Act 1999.
5. The NSW population of Diuris ochroma is threatened by cattle grazing, bulldozer and other vehicular traffic along road edges and fence lines, weed invasion, inappropriate fire regimes including pile burning, and environmental and demographic stochasticity due to its small population size (Miles & McPherson 2004).
6. In view of the above, the Scientific Committee is of the opinion that Diuris ochroma D. L. Jones is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival cease to operate.
Dr Lesley Hughes
Chairperson
Scientific Committee
Proposed Gazettal date: 29/4/05
Exhibition period: 29/4/05 - 24/6/05
References
Bishop A (1996) Field guide to the orchids of New South Wales and Victoria. University of New South Wales Press, Sydney.
Miles J, McPherson P (2004) Targeted flora survey report: Diuris ochroma (Pale Golden Moths), Kybean area, December 2003. NGH Environmental Report to NSW National Parks and Wildlife Service.
Victorian Department of Sustainability and Environment (2003) Advisory List of Rare or Threatened Plants in Victoria 2003. Department of Sustainability and Environment, Victoria, East Melbourne, Victoria.