Homopholis belsonii a perennial grass - endangered species listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the perennial grass Homopholis belsonii C.E. Hubb. as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act. Listing of Endangered species is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

1. Homopholis belsonii C.E. Hubb. (family Poaceae) is described by Jacobs and Wall (1993) as a “rhizomatous and/or stoloniferous perennial to 0.5 m high. Leaves: sheath glabrous, auriculate; ligule 0.8–1.5 mm long; blade 2–4.5 mm wide, glabrous though sometimes ciliate at the base. Inflorescence not fully exserted, common axis 8–15 cm long; primary branches 8–15 cm long, with hairy axils. Spikelets 2 or 3 on a typical lowermost branch, laterally compressed, 4.8–8 mm long. Lower glume equal to the spikelet, 7-nerved, glabrous, with a pronounced rachilla above; upper 4.5–6 mm long, sparsely hairy. Lower lemma 4.2–5.5 mm long, 7-nerved, glabrous to shortly hairy, sterile, palea reduced or absent. Upper lemma c. 65% the length of the spikelet, 5–7-nerved, the margins membranous.”

 

2. Homopholis belsonii occurs north of the Narrabri district in NSW (Jacobs & Wall 1993) and in southern Queensland. It is found mostly within the Brigalow Belt South Bioregion as defined by Thackway & Cresswell (1995), on the NSW north western slopes and plains. H. belsonii has mostly been found on heavy textured cracking soils (Whalley pers. comm. Sept 2011), derived from basalt or of alluvial origin, between the altitudes of 200 and 520 m, (Tremont & Whalley 1993). Based on the survey of Tremont & Whalley (1993), H. belsonii predominantly occurs in places where it has been protected from heavy grazing and where there is partial shade provided by fallen timber or from a small tree or shrub layer.

 

3. There are approximately 25 to 35 populations of Homopholis belsonii based on mapping of the known records (Scott 2011). The number of mature individuals is unknown. H.belsonii is a rhizomatous and/or stoloniferous perennial, so defining an individual is difficult. Tremont & Whalley (1993) found that “overall the species appears to be rare on a landscape scale but locally abundant in particular places”.

 

4. Homopholis belsonii has a highly restricted geographic distribution based on its area of occupancy. The area of occupancy was estimated to be 168 km2, based on 42 2x2 km grid cells, the scale recommended for assessing area of occupancy by IUCN (2010). The extent of occurrence for H. belsonii is moderately restricted. The extent of occurrence was approximately 19 200 km2 covering the populations in NSW and north to the Queensland border. The extent of occurrence was measured by a convex polygon encompassing the currently known sites, as recommended by IUCN (2010), and extending this to the Queensland border in line with the sites within southern Queensland. This gives a more realistic measure of the extent of occurrence as the habitat for H. belsonii extends into southern Queensland.

 

5. The main threats to the survival of Homopholis belsonii are grazing by domestic stock, weed invasion of the habitat, clearing of land for cultivation, disturbance to the soil from road maintenance, and collecting of firewood (Tremont & Whalley 1993; TSSC 2008; Copeland pers. comm. 2010; Whalley pers. comm. 2011). Much of the habitat of H.belsonii has been altered for cropping and the grazing of livestock (Tremont & Whalley 1993). As a consequence, H. belsonii is now found in small and fragmented patches of habitat which are usually located between cultivated or heavily grazed areas as well as along roadside verges, rocky hillsides, frequently flooded areas and along fencelines (Tremont & Whalley 1993). These areas are often disturbed from dumping of rubbish, grazing of domestic stock and collection of firewood. The extent of these threats appear widespread throughout the range of H. belsonii (Tremont & Whalley 1993). Both Hyparrhenia hirta (Coolatai Grass) and the escaped garden plant Opuntia aurantiaca (Tiger Pear) are major weed problems in the NSW locations of the species (Tremont & Whalley 1993, TSSC 2008). ‘Clearing of native vegetation’,‘Invasion of native plant communities by exotic perennial grasses’ and ‘Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants’ are listed as Key Threatening Processes under the Threatened Species Conservation Act, 1995. There are only two populations known to be conserved in a reserve, one in Kirramingly Nature Reserve and another on the edge of Planchonella Nature Reserve. Given the threats across the landscape, it can be inferred that the habitat and most likely, the number of mature individuals of H. belsonii, are undergoing continuing decline.

 

6. Homopholis belsonii C.E. Hubb. is listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 as a Vulnerable Species, and in Queensland under the Nature Conservation Act 1992 as an Endangered Species.

 

7. Homopholis belsonii C.E. Hubb. is not eligible to be listed as a Critically Endangered species.

 

8. Homopholis belsonii C.E. Hubb. is eligible to be listed as an Endangered species as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2010:

 

Clause 7 Restricted geographic distribution and other conditions

The geographic distribution of the species is estimated or inferred to be:

(b)

highly restricted,

and

(d)

a projected or continuing decline is observed, estimated or inferred in either of the key indicators:

 

(a)

an index of abundance appropriate to the taxon, or

 

 

(b)

the geographic distribution, habitat quality or diversity, or genetic diversity of the species.

 

 

 

Associate Professor Michelle Leishman

Chairperson

Scientific Committee

 

Proposed Gazettal date: 17/08/12

Exhibition period: 17/08/12 – 12/10/12

 

References:

 

IUCN Standards and Petitions Subcommittee (2010) ‘Guidelines for Using the IUCN Red List Categories and Criteria Version 8.1.’ Prepared by the Standards and Petitions Subcommittee in March 2010. (http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf)

 

Jacobs SWL, Wall CA (1993) Homopholis. In ‘Flora of New South Wales’ (Ed. GJ Harden) Volume 4, p.462.

 

Scott, J. (2011) Report to the Scientific Committee on Homopholis belsonii. A confidential report to the NSW Scientific Committee.

 

Thackway R, Cresswell ID (1995) An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserves System Cooperative Program. (Version 4.0. Australian Nature Conservation Agency: Canberra.)

 

Tremont RM, Whalley RDB (1993) Final Report for Survey for Homopholis belsonii. Unpublished report. University of New England, Armidale NSW.

 

TSSC (2008) Approved conservation advice for Homopholis belsonii. Threatened Species Scientific Committee for the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

(http://www.environment.gov.au/biodiversity/threatened/species/pubs/2406-conservation-advice.pdf)

 

 

Page last updated: 17 August 2012