Gentiana bredboensis - critically endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the herb Gentiana bredboensis L.G. Adams, as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act, and as a consequence, to omit reference to Gentiana bredboensis L. Adams from Part 1 of Schedule 1 (Endangered species) 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. Gentiana bredboensis (family Gentianaceae) is described by Harden (1992) as an: annual or possibly biennial herb 2–9 cm high, glabrous; stem usually many-branched, minutely scabrous; basal leafless portion very short. Basal leaves 3–6 pairs, sessile, broad-ovate, 8–20 mm long, 8–12 mm wide, margins smooth to minutely scabrous; cauline leaves 3–6 pairs, becoming smaller and thicker up stem, 6–15 mm long and 5–8 mm wide. Flowers 1–6 per plant. Calyx 5–8 mm long; ribs narrow-winged; lobes 2.5–3.5 mm long. Corolla 8–10 mm long, pinkish ribbed outside, pure white inside; lobes spreading, 2–4 mm free. Stipe elongating to 2.5 mm in fruit. Capsule oblong-ovoid, 5–6 mm long.

2. Gentiana bredboensis  is known from a single population, near Jerangle (east of Bredbo), in the Monaro Region on the NSW Southern Tablelands.

4. Gentiana bredboensis produces single small bell-shaped flowers during September and October (DECC 2005).

5. The total number of mature individuals of G. bredboensis is extremely low. A survey undertaken in November 2008 found a population of 20 plants (J Briggs and L. Van Dyke unpublished data). Extreme fluctuations may occur in the population as a result of interactions between the annual life cycle of the species and variation in environmental conditions between years.

6. Gentiana bredboensis has a very highly restricted distribution (Bray 2008). Its area of occupancy is likely to be no greater than 4 km2, based on 2 x 2 km grid cells, the spatial scale of assessment recommended by IUCN (2008).

7. The population of Gentiana bredboensis has undergone a very large reduction over a time frame appropriate to the life cycle of the species. At the time of its discovery in 1967, the total population was estimated to contain several hundred plants, in three small patches separated by a couple of hundred metres on adjacent properties (L. Adams pers. comm.). By 1999 two of these colonies/subpopulations had disappeared, probably as a result of changes to the land management (including changes in stocking rates) (Hogbin 2002); in 2002, the total population was estimated to be 50-200 plants, prompting a revision of the status of the species from Vulnerable to Endangered under the  Threatened Species Conservation Act 1995 (Hogbin 2002; NSW Scientific Committee 2003). A survey conducted in late 2007 estimated the population to be 30-40 plants (R. Rehwinkel and L. Van Dyke unpubl. data). By November 2008, the population had declined to 20 mature individuals, as a result of habitat damage caused by cattle and feral pigs (J Briggs and L. Van Dyke unpublished data), and searches again failed to discover the species in the other two recorded locations (J. Briggs pers. comm.). Between 2002 and 2008 (6 years), the population has potentially declined by 60 - 90%, and has evidently continued to decline since the 1960s. Over the past ten years, a time frame appropriate to the life cycle of the species, the population is likely to have declined by at least 80% (Bray 2008).

8. Gentiana bredboensis is threatened by habitat degradation as a result of trampling by cattle and feral pigs. ‘Predation, habitat degradation, competition and disease transmission by Feral Pigs,  Sus scrofa’ is listed as a Key Threatening Process under the  Threatened Species Conservation Act 1995.

9. Small-scale clearing of habitat may be undertaken to increase access and pasture for livestock grazing. ‘Clearing of native vegetation’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.

10. High fire frequency may have an adverse affect on this species. The ACT Commissioner for the Environment (ACTCE (2004) recommends that G. bredboensis experiences fire no more than once every 6 years. ‘High frequency fires resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition’ is listed as a Key Threatening Process under the  Threatened Species Conservation Act 1995.

11. As G. bredboensis grows in periodically waterlogged areas, changes in hydrology and stream flow associated with projected declines in rainfall (Hennessy  et al. 2004) or water extraction from the Bredbo River may result in drying of the habitat. ‘Alteration to the natural flow regimes of rivers and streams and their floodplains and wetlands’ and ‘Anthropogenic Climate Change’ are listed as Key Threatening Processes under the  Threatened Species Conservation Act 1995.

12. The small range and population size of G. bredboensis makes this species vulnerable to environmental and demographic stochasticity.

13. Other threats include nutrient enrichment as a result of runoff from improved pastures adjacent to the population and resulting competition from exotic pasture species. ‘Invasion of native plant communities by exotic perennial grasses’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.

14. Gentiana bredboensis L. Adams 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 14

The species has undergone, is observed, estimated, inferred or reasonably suspected to have undergone or is likely to undergo within a time frame appropriate to the life cycle and habitat characteristics of the taxon:

(a) a very large reduction in population size

based on:

(d) an index of abundance appropriate to the taxon

(e) geographic distribution, habitat quality or diversity, or genetic diversity.

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, or

(ii) geographic distribution, habitat quality or diversity, or genetic diversity

(e) the following conditions apply:

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations

(iii) extreme fluctuations are observed or inferred to occur in either:

(A) an index of abundance appropriate to the taxon.

Clause 16

The estimated total number of mature individuals of the species is:

(a) very low

and

(d) a projected or continuing decline is observed, estimated or inferred in either:

(i) an index of abundance appropriate to the taxon, or

(ii) geographic distribution, habitat quality or diversity, or genetic diversity

(e) the following conditions:

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations

(iii) extreme fluctuations are observed or inferred to occur in:

(A) an index of abundance appropriate to the taxon.

Clause 17

The total number of mature individuals of the species is observed, estimated or inferred to be:

(a) extremely low.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 11/12/09
Exhibition period: 11/12/09 – 05/02/10

References:

ACT Commissioner for the Environment (ACTCE) (2004) ‘State of the Environment Report, Fire management in threatened ecological communities and threatened species’. ACTCE

Adams LG, Williams, JB (1988) ‘Gentiana sect.  Chrondrophyllae (Gentianaceae) in Australia’,  Telopea 3, 167-176.

Bray C (2008) Conservation status of Gentiana bredboensis L. Adams (Gentianaceae) in New South Wales. Report to the NSW Scientific Committee, Sydney.

Department of Environment & Climate Change New South Wales (DECC) (2005) Bredbo Gentian - profile.

Harden GJ (1992) Gentianaceae. In ‘Flora of New South Wales, Vol. 3’. (Ed. GJ Harden) pp. 508-512 (University of NSW Press: Kensington, NSW).

Hennessy K, Page C, McInness K, Jones R, Bathols J, Collins D, Jones D (2004) ‘Climate change in New South Wales. Part 1: Past climate variability and projected changes in average climate.’ (CSIRO: Melbourne).

Hogbin P (2002) ‘Review of the TSC Act Flora Schedules: Recommendations to the Scientific Committee. Final Summary Report Dec 2002.’ NSW NPWS, Hurstville, NSW.

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).

NSW Scientific Committee (2003) ‘Gentiana bredboensis - endangered species listing. Final determination’.