Eucalyptus oblonga DC. population at Bateau Bay, Forresters Beach and Tumbi Umbi in the Wyong 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 oblonga DC. at Bateau Bay, Forresters Beach and Tumbi Umbi in the Wyong local government area as an ENDANGERED POPULATION in Part 2 of Schedule 1 of the Act, and as a consequence, to omit reference to the population of Eucalyptus oblonga Blakely at Bateau Bay in the Wyong local government area from Part 2 of Schedule 1 (Endangered population) of the Act. Listing of Endangered populations is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

1. Eucalyptus oblonga DC. (family Myrtaceae) a narrow-leaved stringybark, is described by Hill (2002) as: 'Tree to 15m high; bark persistent on trunk and larger branches or throughout, grey to red-brown, stringy. Juvenile leaves disjunct, broad-lanceolate, glossy green, hispid. Adult leaves disjunct, lanceolate, 6-9cm long, 1.4-2.8cm wide, green, glossy, concolorous. Umbellasters 7- to ≥ 11-flowered; peduncle narrowly-flattened or angular, 6-12mm long; pedicels angular, 1-2mm long. Buds cylindrical or fusiform, 6-7mm long, 2-3mm diam., scar absent; calyptra conical, at least as long and as wide as hypanthium. Fruit globose or hemispherical, 6-8mm long, 6-9mm diam.; disc flat to raised; valves rim-level or exserted. Restricted and localised in dry sclerophyll woodland on extremely infertile sandy soils on sandstone.' It occurs from the NSW Central Coast south to about Nowra.

 

2. Eucalyptus oblonga 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. A population of Eucalyptus oblonga occurs in the Wyong local government area, within the Sydney Basin Bioregion of Thackway and Creswell (1995). The area occupied by this population is defined by the suburbs of Bateau Bay, Forresters Beach and Tumbi Umbi (NSW Department of Lands 2009). The population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi represents the eastern limit of the species' range. Eucalyptus oblonga has been recorded from areas further north and south, however these records are not from coastal areas.

 

4. The population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi includes occurrences on the Patonga Claystone Formation and derived soils, corresponding to the Woodburys Bridge Soil Landscape (Murphy 1993). These occurrences are unusual and of significant conservation value as elsewhere the species occurs on sandstone (Hill 2009). One site has been heavily disturbed and a shallow layer of loose, coastal sand previously observed at the site, and identified as corresponding to the Norah Head Soil Landscape (Murphy 1993), is no longer apparent.

 

5. An initial survey of the population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi detected approximately 20 trees. Up to 40 trees are thought to have existed prior to 2007 in which year 9 trees were felled (Mackenzie 2008). A 2008 survey (Mackenzie 2008) found only 7 adults and a cohort of approximately 50 seedlings distributed over an area of approximately 5 ha.

 

6. Fragmentation, grazing and small-scale physical disturbance have resulted in the establishment of invasive species such as Lantana (Lantana camara) and Bitou Bush (Chrysanthemoides monilifera) at the site. These species may pose an additional future threat to the population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi by contributing to lower rates of establishment, and reducing habitat quality and area. ‘Invasion of native plant communities by Chrysanthemoides monilifera’ and ‘Invasion, establishment and spread of Lantana (Lantana camara L. sens. lat)’ are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995.

 

7. The population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi is threatened by demographic and environmental stochasticity due to its small size and restricted distribution, potential clearing for urban development and competition with 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.

 

8. Eucalyptus oblonga can be confused with the related Eucalyptus camfieldii (Heart-leaved Stringybark) which also occurs in the general area, and which is listed as a Vulnerable species under the Threatened Species Conservation Act 1995. Hybrids between these two species are considered part of the population of Eucalyptus oblonga at Bateau Bay, Forresters Beach and Tumbi Umbi.

 

9. The population of Eucalyptus oblonga DC. at Bateau Bay, Forresters Beach and Tumbi Umbi in the Wyong 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 12 Large reduction in population size

The size of the population 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 large reduction based on 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.

 

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:

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

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

 

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:

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

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

 

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: 17/12/10 – 11/02/11

 

References:

Hill KD (2002) Eucalyptus. In ‘Flora of New South Wales’. (Ed. G. J. Harden) pp. 96-167. (University of New South Wales Press, University of New South Wales, Kensington).

 

Hill K (2009) Eucalyptus oblonga. In ‘PlantNET - The Plant Information Network System of Botanic Gardens Trust, Sydney, Australia (version 2.0)’.http://plantnet.rbgsyd.nsw.gov.au, accessed on 17 November 2009.

 

Mackenzie B (2008) Eucalyptus oblonga endangered population at Bateau Bay – results of field inspection and recommendations for revision of listing under the NSW Threatened Species Conservation Act.

 

Murphy CL (1993) 'Soil landscapes of the Gosford-Lake Macquarie 1:100 000 sheet' Department of Conservation and Land Management, Sydney.

 

NSW Department of Lands (2009) Boundaries of the suburbs of Bateau Bay, Forresters Beach and Tumbi Umbi. In ‘SIX – Spatial Information Exchange, NSW Department of Lands’. http://imagery.maps.nsw.gov.au/?role=mysuburb&search=suburb&suburb=bateau%20bay#, http://imagery.maps.nsw.gov.au/?role=mysuburb&search=suburb&suburb=forresters%20beach#, http://imagery.maps.nsw.gov.au/?role=mysuburb&search=suburb&suburb=tumbi%20umbi# accessed on 17 November 2009.

 

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

Page last updated: 28 February 2011