Isotropis foliosa - rejection of species listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to REJECT a proposal to list Isotropis foliosa Crisp as a Vulnerable species in Part 1 of Schedule 2 of the Act. Rejection of nominations is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

1. Isotropis foliosa Crisp (family Fabaceae) is described by Porteners (2002) as a “Subshrub to c. 60 cm high, rusty or whitish-pubescent. Leaves 1-foliolate, + ovate, 8-30 mm long, 8-15 mm wide, apex obtuse or acute, often with a recurved point, sparsely hairy to glabrous; petiole 6-15 mm long; stipules subulate, 1-2 mm long. Inflorescence of loose, terminal racemes; pedicels 2-6 mm long; bracts narrow-triangular, 2-3 mm long. Calyx 8-9 mm long. Corolla 10-15 mm long; standard orange with purple veins and a yellow spot at base; wings and keel orange to red. Ovary villous. Pods obliquely narrow-obovoid, 15-30 mm long, pubescent.”

 

2. Isotropis foliosa occurs from southern Queensland, where it is very uncommon, into New South Wales as far south as the upper Hunter Valley. In New South Wales at least 27 populations are known. Most localities are on the North Western Slopes although several populations have also been recorded from the Central Western Slopes. A further three records are known from the North Coast region although, at one of these locations (Rivertree), the species has not been collected for over 95 years.

 

3. Isotropis foliosa most commonly grows in shallow soils on rocky slopes at altitudes of 300-700 m above sea level. The underlying geology can be variable as populations are known to occur on basalt, granite, metasediments and sandstone. The vegetation is usually a low woodland of stunted Eucalyptus and Callitris with relatively little ground cover. The coastal populations grow in a considerably different habitat in deep alluvial soil on relatively flat river terraces. Flowering mostly occurs in spring with occasional flushes in summer and autumn.

 

4. At least 10 populations of Isotropis foliosa are known to occur in conservation reserves. On the North Western Slopes the species has been recorded in Warialda Community Conservation Area (CCA), Bingara CCA, Gwydir River CCA, Leard CCA and Kelvin CCA, while two North Coast populations are reserved within Oxley Wild Rivers National Park (NP). A small population of Isotropis foliosa is also reserved close to the southern limit of the species in Wollemi NP.

 

5. The total known population of Isotropis foliosa in New South Wales is estimated to consist of at least 11 000 mature individuals (Copeland et al. 2008). Several thousand additional seedlings and juveniles are also known to occur. Populations of Isotropis foliosa are scattered over a total extent of occurrence in NSW exceeding 60000 km2. Within the range, the species occupies at least 100km2 based on 2 x 2 km grid cells, the scale recommended by IUCN (2008) for estimating areas of occupancy. There is no evidence of any appreciable continuing decline in the overall population of the species.

 

6. In 2005 the NSW Scientific Committee made a Preliminary Determination to support a proposal to list Isotropis foliosa as a Vulnerable species in Schedule 2 of the NSW Threatened Species Conservation Act. Since then, a number of additional populations of Isotropis foliosa have been discovered and/or documented for the first time. The total number of mature individuals is now believed to be considerably higher than previous estimates suggest and several additional populations have been included within the conservation reserve estate following the recent gazettal of community conservation reserves under the Western Regional Assessment (Brigalow and Nandewar Community Conservation Area Act 2005). A large population in excess of 10 000 plants has been documented to occur in a steep, remote section of Daffeys Creek State Forest and these plants appear to be under no apparent threat.

 

7. In view of the above the Scientific Committee is of the opinion that Isotropis foliosa Crisp is not eligible to be listed as a Vulnerable species in Schedule 2 of the Act.

 

 

 

 

 

Dr Richard Major

Chairperson

Scientific Committee

Proposed Gazettal date: 12/06/09

Exhibition period: 12/06/09 – 07/08/09

 

References

 

Copeland LM, Scott J, Keith D (2008) ‘Conservation status of Isotropis foliosa Crisp (Fabaceae) in New South Wales.’ Report to the NSW Scientific Committee, Sydney.

 

IUCN (2008) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland)

 

Porteners MF (2002) Isotropis. In ‘Flora of New South Wales. Vol. 2 Revised Edition’. (Ed. GJ Harden) pp. 528-529 (University of New South Wales Press: Sydney)

Page last updated: 28 February 2011