Eucalyptus recurva - critically 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 mallee Eucalyptus recurva Crisp as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act, and as a consequence, to omit reference to Eucalyptus recurva Crisp 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.

 

The Scientific Committee has found that:

 

1. Eucalyptus recurva Crisp (Mongarlowe Mallee) (family Myrtaceae) is a small multi-stemmed tree described by Hill (2002) as follows: “Mallee to 1.5 m high; bark smooth, grey, orange, green or yellow, shedding in long ribbons. Juvenile leaves opposite, elliptic to ovate, glossy green. Adult leaves opposite, elliptic or ovate, 1–3 cm long, 0.5–0.8 cm wide, green, glossy, concolorous. Umbellasters 3-flowered; peduncle narrowly flattened or angular, 3–5 mm long; pedicels terete, 1–2 mm long. Buds ovoid, 4–5 mm long, 3–4 mm diam., scar present, but outer calyptra not shedding cleanly; calyptra hemispherical, shorter and narrower than hypanthium. Fruit hemispherical or conical, 3–4 mm long, 4–5 mm diam.; disc raised; valves exserted.”

 

2. Eucalyptus recurva was first discovered in 1985 and subsequently described by Crisp (1988), who found it to be distinct from any other known species, but most closely related to E. vernicosa.

 

3. Eucalyptus recurva is endemic to New South Wales and known only from the Mongarlowe district in heathland and around the margins of eucalypt woodland. It typically occurs in shallow sandy loam on quartzite slopes. Plants flower in summer and are likely to be pollinated by insects. Like all mallee eucalypts, the plants have multiple stems arising from a lignotuber, a subterranean woody organ from which new shoots may resprout after the canopy is burnt in a bushfire (NSW NPWS 2003).

 

4. Eucalyptus recurva has a very highly restricted geographic distribution. The species is known from four localities within a total extent of occurrence of no more than 30 km2 and an area of occupancy of 16 km2, based on occupancy of four 2 × 2 km grid cells, the scale of assessment recommended by IUCN (2008). A helicopter survey of potential habitat, undertaken in January 2001, failed to locate other occurrences of the species (NSW NPWS 2003; J. D. Briggs pers. comm. 2008).

 

5. The total population of Eucalyptus recurva comprises only five mature individuals. These are isolated from one another by distances of more than 2 km and up to 30 km, except at one location where two plants are approximately 40 m apart. The size of the lignotubers suggests that the plants are of considerable age, probably at least several hundred years old (NSW NPWS 2003).

 

6. While all individuals of E. recurva have persisted since their discovery at various times in the last 7-23 years, longer term trends in the population are unknown. There are currently no juvenile plants in the population and there is no evidence of recent seedling recruitment. Seed viability is very low, with an estimated 0.6 viable seeds set per fruit (NPWS 2003). The large distances between most plants are likely to limit opportunities for cross-pollination and may be linked to the low levels of viable seed set.

 

7. The very small number of individuals and their distribution as isolated individuals at few locations makes E. recurva highly susceptible to stochastic events such as wildfire, damage associated with human access, disease, extreme weather events or severe drought. The extremely narrow genetic base of the existing population also suggests that the species may have limited capacity to adapt to future changes in the environment. One of the four occurrences is threatened by habitat loss and degradation associated with clay mining. Ameliorative measures, including re-routing of an access road and construction of a fence, have helped to reduce immediate risks to the plants (J. D. Briggs pers. comm. 2008). At the other three locations, collection of plant material, soil compaction, vehicular damage and habitat degradation associated with unregulated human access potentially threaten the species. Visitation also poses the risk of introduction of soil-borne fungal pathogens such as Phytophthora cinnamomi (NSW NPWS 2003). One of the plants suffered major die-back of its stems in the late 1990s (NSW NPWS 2003). The cause of this dieback and the susceptibility of the species to Phytophthora cinnamomi remain unknown. The continuing failure to reproduce in the wild precludes replacement of any existing plants that may be lost to senescence, disease, incidental damage, habitat degradation or stochastic events. The species is therefore projected to undergo a future decline. ‘Clearing of Native Vegetation’ and ‘Infection of native plants by Phytophthora cinnamomi’ are listed as Key Threatening Processes under the Threatened Species Conservation Act 1995.

 

8. Eucalyptus recurva is not known to occur in any conservation reserves in New South Wales.

 

9. Eucalyptus recurva Crisp 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

 

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

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

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: 31/07/09

Exhibition period: 31/07/09 - 25/09/09

References:

Crisp MD (1988) Eucalyputs recurva (Myrtaceae), a new species from the Southern Tablelands of New South Wales. Telopea 3, 23-230.

IUCN (2003) 'Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.' (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiverstiy Assessemnts Sub-committee: Switzerland)

Hill KD (2002) Eucalyptus. In 'Flora of New South Wales. Vol. 2; Revised Edition'. (Ed. GJ Harden) pp. 96-194 (University of New South Wales Press: Sydney)

NSW NPWS (2003) 'Draft Recovery Plan for the Mongarlowe Mallee (Eucalyptus recurva)'. NSW National Parks and Wildlife Service, Sydney.

Page last updated: 28 February 2011