Zieria smithii population, Diggers Head - 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 low growing form of the shrub Zieria smithii Jackson at Diggers Head as an ENDANGERED POPULATION on Part 2 of Schedule 1 of the Threatened Species Conservation Act. Listing of endangered populations is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1. Zieria smithii Jackson is generally an upright shrub to 2m high from the margins of rainforest and wet sclerophyll forests. On headlands, low growing to prostrate forms of the species are known. It is not listed on Schedule 1 of the Threatened Species Conservation Act and hence the population is eligible for consideration as an endangered population.

2. The low growing form of Zieria smithii at Diggers Head has the following characteristics 'low scrambling shrub to one metre or more in diameter; branches not ridged or warted but young parts covered densely with fine hairs. Leaves with central leaflet oblong lanceolate, 25-50 mm long, 10-14 mm wide at the broadest part, apex obtuse, lateral leaves similar and about 4/5ths the length of the central one. Leaf margins entire, discolorous, both surfaces dotted with oil glands, petiole 10-13mm long.' Key differences from the typical upright Zieria smithii are 'low growing habit, a lack of warts on branches, dense fine hairs on young parts, and obtuse leaf apicies'. The form of Z. smithii at Diggers Head also differs from the prostrate Zieria prostrata in being a more loosely branched shrub, with no ridges on the stems, fine hairs on the younger plants, larger leaves and larger oil glands on the leaves.

3.It occurs on a headland (Diggers Head, to the north of Coffs Harbour) in association with dwarf heath and Themeda australis. The area is not reserved.

4.The population is known to consist of only a few individuals.

5. The population is morphologically distinct from other populations of Zieria smithii and other Zieria species. Use of DNA markers has shown the population to be genetically divergent from the nearest upright population of Zieria smithii, other upright populations of Zieria smithii, other prostrate forms of Zieria smithii and Zieria prostrata.

6. The population, and associated habitat, is currently threatened by encroachment of weeds, especially bitou bush and kikuyu grass.

7. In view of 4, 5 and 6 above, the Scientific Committee is of the view that the population has been reduced to such a critical level and its habitat so drastically reduced that it is in immediate danger of extinction; it is likely to be genetically distinct; and it is of significant conservation value as it is morphologically distinct from other Zieria smithii plants and other species of Zieria. Accordingly, the Committee considers that the population meets the criteria for listing as an endangered population on Part 2 of Schedule 1 of the Threatened Species Conservation Act.

Proposed gazettal date: 18/9/98

Exhibition Period: 18/9/98 to 23/10/98

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Page last updated: 28 February 2011