Eucalyptus langleyi L.A.S. Johnson & Blaxell population north of the Shoalhaven River in the Shoalhaven local government area - endangered population listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list a population of the tree Eucalyptus langleyi L.A.S. Johnson & Blaxell north of the Shoalhaven River in the Shoalhaven local government area as an ENDANGERD POPULATION in Part 2 of Schedule 1 of the Act. Listing of Endangered populations is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

1. Eucalyptus langleyi L.A.S. Johnson & Blaxell (family Myrtaceae), also known as Albatross Mallee, is described by Hill & Johnson (1991) as a: ‘Mallee to 5 m high. Bark smooth, brown, shedding in long ribbons. Young shoots prominently 4-winged. Juvenile leaves glossy green, broad-lanceolate to ovate. Adult leaves disjunct, lanceolate, acuminate, sometimes oblique, coriaceous, glossy green, 8-18 mm long, 1.8-4.0 mm wide; petioles 8-18 mm long, winged, wings decurrent with wings on twigs; lateral veins obscure, anastomosing, at 10-20° to midrib; intramarginal vein obscure, leaf margin prominently thickened. Umbellasters axillary, 7-flowered; peduncles broadly winged, 8-12 mm long, to 7 mm wide apically; pedicels 0-2 mm long, angular. Mature buds irregularly pyriform, rugose, 11-14 mm long, 4-6 mm diam.; calyptra less than ¼ as long as hypanthium, hemispherical, very broadly obtuse. Stamens all fertile; filaments inflexed into hypanthium in bud; anthers dorsifixed, versatile, reniform, dehiscing through confluent slits. Fruits cup-shaped, 3- or 4-locular, sometimes apically constricted, 8-10 mm long, 8-10 mm in diameter, sometimes with 1-3 vertical ridges; calyptra scar a narrow groove around hypanthium, stemonophore 0.5-1 mm wide, flat, ultimately depressed to meet disc; disc enclosed, flat, 1-1.5 mm wide; valves enclosed, tips often exserted. Seeds dull, grey-brown, angular, reniform, to 2.5 mm long; chaff similar, smaller’. Eucalyptus langleyi can be distinguished from the closely related E. burgessiana by its flattened stems with adult leaves that are only 2.5 cm wide.

 

2. Eucalyptus langleyi L.A.S. Johnson & Blaxell is not currently listed as an Endangered species in Part 1 of Schedule 1 or a Critically Endangered species in Part 1 of Schedule 1A of the Threatened Species Conservation Act 1995 and as a consequence populations of this species are eligible to be listed as Endangered populations under the Act.

 

3. Eucalyptus langleyi is currently listed as a Vulnerable species in Part 1 of Schedule 2 of the Act. It is also listed as a Vulnerable species under the Environment Protection and Biodiversity Conservation Act 1999. It has a very limited distribution in NSW mostly within a 17 km x 7 km area and is known from 35 sites with a total population of over 7600 plants (Mills 2010). E. langleyi is located predominately to the southwest of Nowra with a disjunct population north of the Shoalhaven River in the vicinity of Bomaderry Creek, near Nerang Road, Bomaderry http://www.threatenedspecies.environment.nsw.gov.au/tsprofile/profile.aspx?id=10298).

 

4. This population of E. langleyi is the most northerly population of the species and is the only E. langleyi population north of the Shoalhaven River. The population is approximately 5 km from the closest population located to the southwest across the Shoalhaven River. The E. langleyi population north of the Shoalhaven River in the Shoalhaven local government area has important conservation value as it occurs at 30-40 m above sea level whereas other populations are generally found at 130-225 m above sea level (Barratt in litt.). Plants in the E. langleyi population north of the Shoalhaven River in the Shoalhaven local government area occur as a series of fragmented stands across approximately 1.3 km2 and occur on both sides of the boundary between Bomaderry Creek Regional Park and land owned by Shoalhaven City Council (Barratt in litt.).

 

5. The total population size of the Eucalyptus langleyi population north of the Shoalhaven River in the Shoalhaven local government area in 1998 was estimated at 32 plants but a survey in 2008 found only 20 of these still alive (Barratt in litt) while Mills (2010) found 25 trees. This represents a decline of ~ 22 to 38% over ten years. Reproduction has been poor in recent years and no successful recruitment has occurred within the population (Barratt in litt.).

 

6. The genetic distinctiveness of the population is unknown. Insects are presumed to be the primary pollinators of Eucalyptus langleyi (John Briggs pers. comm. Nov 2009), limiting the distance over which pollen will be exchanged between plants and populations. Current estimates of pollen movement for eucalypts are <1 km with rare events >5 km (Potts et al. 2003) while seed dispersal is predicted to be less than twice tree height although some dispersal as far as 310 m is predicted (Wallace and Trueman 1995; Barbour et al. 2003). This suggests that the population may have gene combinations not present in other populations.

 

7. The Eucalyptus langleyi population north of the Shoalhaven River in the Shoalhaven local government area occurs on rocky sloping Nowra Sandstone outcrops in a highly disturbed environment that is used for recreational activities and is also impacted by weeds and rubbish dumping (Barratt in litt.). Construction and maintenance of urban infrastructure such as roads, powerlines and pipelines also pose a threat to the population. One of the options for a new road planned by the Shoalhaven City Council would bisect the population and may destroy 2 or 3 plants (Barratt in litt.; Shoalhaven City Council 2010 in litt.). Clearing and inappropriate fire regimes are considered to be further threats to the population (Barratt in litt.). Habitat quality around each of the stands varies. ‘Clearing of native vegetation’ and ‘High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition’ are listed as Key Threatening Processes under the Threatened Species Conservation Act 1995.

 

8. The population of Eucalyptus langleyi is threatened by demographic and environmental stochasticity due to its small population size and restricted distribution, potential clearing for road development and competition from invasive species. It may be inferred from these threats that the population is undergoing a continuing decline in abundance, geographic distribution and/or habitat quality.

 

9. The population of Eucalyptus langleyi L.A.S.Johnson & Blaxell north of the Shoalhaven River in the Shoalhaven local government area is eligible to be listed as an Endangered population 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 11 Criteria for listing determinations by Scientific Committee

The population is facing a very high risk of extinction in New South Wales in the near future as, in the opinion of the Scientific Committee, it satisfies any one or more of the following paragraphs and also meets the criteria specified in one or more of the following clauses:

(a) it is disjunct or near the limit of its geographic range,

(c) it is otherwise of significant conservation value.

 

Clause 13 Highly restricted geographic distribution of population and other conditions

The geographic distribution of the population is estimated or inferred to be highly restricted and either:

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

(b) the geographic distribution, habitat quality or diversity, or genetic diversity, or

(b) the following conditions apply:

(i) the population or habitat is observed or inferred to be severely fragmented;

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

 

Clause 14 Low numbers of mature individual in population and other conditions

The estimated total number of mature individuals in the population is low and either:

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

(b) the geographic distribution, habitat quality or diversity, or genetic diversity, or

(b) the following conditions apply:

(i) the population or habitat is observed or inferred to be severely fragmented,

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

 

Clause 15 Very low numbers of mature individuals in population

The estimated total number of mature individuals of the population is observed,

estimated or inferred to be very low.

 

 

Dr Richard Major

Chairperson

Scientific Committee

 

Proposed Gazettal date: 17/12/10

Exhibition period: 17/21/10

 

References:

 

Barbour RC, Potts BM, Vaillancourt RE (2003) Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild. Australian Journal of Botany 51, 429-439.

 

Hill KD, Johnson LAS (1991) Systematic studies in the eucalypts - 3. New taxa and combinations in Eucalyptus (Myrtaceae). Telopea 4, 259.

 

Mills K (2010) Rare Plant Species in the Illawarra 4: Eucalyptus langleyi (Myrtacea). Illawarra Vegetation Studies (20), Coachwood Publishing, Jamberoo, NSW

 

Potts BM, Barbour RC, Hingston AB, Vaillancourt RE (2003) Genetic pollution of native eucalypt gene pools – identifying the risks. Australian Journal of Botany 51, 1-25.

 

Wallace HM, Trueman SJ (1995) Dispersal of Eucalyptus torelliana seeds by the resin-collecting stingless bee, Trigona carbonaria. Oecologia 104, 12-16.

Page last updated: 28 February 2011