Zieria granulata (Illawarra Zieria) Recovery Plan

NSW Department of Environment and Conservation, 2005
ISBN: 1 7412 2143 9

Appendix 3: Species profile and environmental impact assessment guidelines

Zieria granulata

C. Moore ex Benth.
Common Name: Illawarra Zieria

Conservation Status

Zieria granulata is listed as an endangered species on Schedule 1 of the NSW Threatened Species Conservation Act 1995 (NSW TSC Act) and as an endangered species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

Description

Z. granulata is a tall bushy shrub or small tree that can grow to six metres. The entire plant is densely covered with glandular tubercles (small wart-like outgrowths) which give the leaves a strong aroma when crushed. Leaves are palmately trifoliate (three-fingered), opposite and petiolate. The central leaflet is linear, 19.5 to 42.5 mm long, 0.5 to 1.5 mm broad with an obtuse (blunt) apex. Leaf margins are revolute (downward curved) with a dull green upper surface and whitish lower surface. The inflorescence is axillary, shorter than the leaves and 50 to 180 flowered. Flowers are white, four petalled, and 3.5 to 4.5 mm in diameter. The fruit is a dry, light brown, four-chambered capsule. Seeds are dark reddish-brown, and have an elaiosome (ant attracting appendage) (Armstrong 2002; M. Robinson, pers. comm.).

Distribution

Z. granulata is restricted to the Illawarra region, south of Sydney, where it is recorded from 26 populations (or 97 fragmented sites). The species primarily occupies the coastal lowlands between Oak Flats and Toolijooa in the local government areas of Shellharbour and Kiama. This is a range of approximately 22 kilometres (DEC 2005).

A disjunct site occurs at Kanahooka in Wollongong local government area. This site occurs on fill material derived from Bumbo Latite and it appears that Z. granulata propagules were introduced to the site via this material (Mills & Jakeman 1993; Robinson 1999).

Recorded occurrences in conservation reserves

Z. granulata has been recorded from one conservation reserve, Budderoo National Park.

Habitat

The preferred landform of Z. granulata is dry ridge tops and rocky outcrops with shallow, volcanic soils (DEC 2005). The species is less frequently found on the moist slopes of the Illawarra escarpment and in low-lying areas on Quaternary sediments (DEC 2005).

The vast majority of Z. granulata sites occur on Bumbo Latite although the species has been recorded growing on a variety of substrates (DEC 2005). The altitudinal range of the species is five to 510 metres although most sites occur below 150 metres (DEC 2005).

Three vegetation types are considered to provide typical natural habitat for the species; Melaleuca armillaris scrub to tall shrubland, subtropical rainforest, and Eucalyptus tereticornis woodland to open forest. These vegetation types are listed as endangered ecological communities on Schedule 1 of the NSW TSC Act, where they are named Melaleuca armillaris Tall Shrubland, Illawarra Subtropical Rainforest and Illawarra Lowlands Grassy Woodland respectively (DEC 2005).

DEC (2005) states that the species has also been recorded in the following vegetation types:

  • Backhousia myrtifolia (Ironwood) low closed forest;
  • Eucalyptus paniculata (Grey Ironbark) open forest;
  • Dodonaea viscosa ssp. angustifolia (Sticky Hop Bush) scrub to open scrub;
  • Syncarpia glomulifera (Turpentine) woodland;
  • Eucalyptus botryoides (Bangalay) forest;
  • Leptospermum laevigatum (Coastal Tea-tree) open scrub; and
  • Eucalyptus fastigata (Brown Barrel) forest.

Much of the natural habitat of Z. granulata has been removed and many sites now occupy road verges and paddock edges (Mills & Jakeman 1993).

Ecology

Armstrong (2002) states that the flowering period of Z. granulata is from late spring to summer, although Robinson (1999) has observed the species flowering in early spring. It is unknown at what age the species is capable of flowering or whether individuals flower regularly or sporadically. The species failed to flower at many sites during the drought of 2002/2003 (DEC 2005).

Zieria flowers are morphologically hermaphrodite, having both male and female organs present in each flower (Armstrong 2002). It is unknown whether Z. granulata is capable of self-pollination. A genetic study of

Z. granulata plants at Tabbagong Forest and Bombo found that a low level of genetic diversity was present, indicating that significant cross-pollination was likely to be occurring within that study area (Sharma & Young 2000).

Nectar seeking flies (viz. Biblio imitator, Biblionidae; Callophora hilli, Calliphoridae) have been observed on Z. granulata flowers and appear to be effective pollen vectors (Armstrong 2002). These flies are considered to be generalist and accidental pollinators, they are strong fliers and are capable of traversing open spaces (Robinson 1999). An Eastern Spinebill (Acanthorhynchus tenuirostris) has also been observed probing the flowers of Z. granulata (Robinson 1999).

Seed dispersal in Zieria spp. is by forcible ejection from the mature coccus (fruit) (Armstrong 2002). The presence of an elaiosome (ant-attracting appendage) on the seed indicates that secondary dispersal by ants (termed myrmecochory) may also occur (Robinson 1999). It appears likely that some form of dormancy mechanism exists for Z. granulata seed and that a disturbance related trigger is required to break this dormancy (DEC 2005). However, low levels of seedling recruitment have been observed in the inter-disturbance period (A. Bofeldt, Wollongong Botanic Gardens, pers. comm.). There is no published information about the longevity and viability of Z. granulata seed.

Z. granulata has been observed to coppice (reshoot from the base of mature stems) in response to physical disturbance, including grazing and slashing. It is unknown at what age the species is capable of this (DEC 2005).

The response of the species to fire has not been observed. As vegetative reproduction from sub-surface epicormic buds (suckering) has not been reported for Z. granulata, it is considered unlikely that the species would survive a fire of sufficient intensity to destroy the above ground parts of the plant (DEC 2005).

Threats

Extensive clearing of the Illawarra lowlands since European settlement has destroyed much of the natural habitat of Z. granulata and remaining habitat is limited and highly fragmented. The majority of Z. granulata sites are small, isolated and occupy freehold land that may be subject to competing landuses (DEC 2005).

The main threat to the species is the further loss of habitat as a result of quarrying, agricultural clearing, residential development and road construction. Agricultural activities (including grazing and trampling by livestock, vegetation slashing and herbicide spraying), roadside and dry stone wall maintenance activities, weed invasion and rubbish dumping also threaten Z. granulata at a number of sites (DEC 2005).

Management

Future management must aim to increase the level of legislative protection afforded land upon which the species occurs. This can be facilitated on public and private land through a range of mechanisms including:

  • Conservation covenants and agreements under the NSW TSC Act, the National Parks & Wildlife Act 1974, and the Conveyancing Act 1919;
  • Environmental Planning Instruments prepared under Part 3 of the Environmental Planning & Assessment Act 1979; and
  • Critical habitat declared under the NSW TSC Act.

Appropriate threat and habitat management practices include bush regeneration to restore and maintain suitable habitat and fencing to restrict access by livestock and machinery.

Initiatives to raise awareness of the species in land managers and field workers are required to ensure that the species is not inadvertently damaged during road maintenance and weed control activities.

Remnant vegetation containing Z. granulata should also be managed to prevent frequent burning.

Recovery Plans

A recovery plan for the species was approved in January 2005.

For Further Information contact

Threatened Species Unit, Metropolitan Region, Environment Protection and Regulation Division, Department of Environment and Conservation (NSW), PO Box 1967, Hurstville NSW 2220 Phone 02 9585 6678.

www.npws.nsw.gov.au

References

Armstrong J.A. (2002) The genus Zieria (Rutaceae): a systematic and evolutionary study. Australian Systematic Botany Vol. 15 (3): 277 463.

Mills K. & Jakeman J. (1993) Survey of the Rare Plant Species Zieria granulata (RUTACEAE) Illawarra Region, New South Wales. Unpublished report prepared for Kiama Municipal Council.

DEC (2005) Zieria granulata (Illawarra Zieria) Recovery Plan. Department of Environment and Conservation (NSW), Hurstville NSW

Robinson M.V. (1999) Section 5A Assessment of the Endangered Zieria granulata at the proposed North Kiama By-pass. Unpublished report for the NSW Roads and Traffic Authority.

IMPORTANT DISCLAIMER

The NSW Department of Environment and Conservation and the editor expressly disclaim all liability and responsibility to any person, whether a purchaser or reader of this document or not, in respect of anything done or omitted to be done by any person in reliance upon the contents of this document although every effort has been made to ensure that the information presented in this document is accurate and up to date.

Zieria granulata

(F. Muell.) C. Moore ex Benth
Common name: Illawarra Zieria

The following information is provided to assist authors of Species Impact Statements, development and activity proponents, and determining and consent authorities, who are required to prepare or review assessments of likely impacts on threatened species pursuant to the provisions of the Environmental Planning and Assessment Act 1979. These guidelines should be read in conjunction with the NPWS Information Circular No. 2: Threatened Species Assessment under the EP&A Act: The 8 Part Test of Significance (November 1996).

Survey

Survey for Zieria granulata may be undertaken at any time of the year. A combination of leaf characteristics and habit should enable the species to be identified in the absence of flowers. The species is most readily observed however during its flowering season when plants are covered in a dense mass of white flowers.

Survey should not necessarily be confined to areas of remnant native vegetation. Z. granulata plants have been recorded growing in highly disturbed environments including along roadsides and fencelines, amongst regrowth in cleared paddocks and in dense Lantana thickets.

Where new sites are located, site details including plant numbers, habitat and location should be recorded and forwarded to the DEC.

Life cycle of the species

The ecology of Z. granulata is described in the draft recovery plan and summarised in the species profile. Proposals that are likely to impact upon the life cycle of the species include those that contribute to the following:

  • Loss of individuals
    The significance of a particular activity that physically destroys individual plants will require an examination of the number of plants to be destroyed in relation to the size of the population and a discussion of how recruitment, gene flow and the overall health of the population will be effected.

  • Loss and fragmentation of habitat
    As the breeding system of Z. granulata is not understood, the effects of loss and fragmentation of its habitat are not known. Total destruction of habitat will place a local population at risk of extinction.

  • Modification of habitat
    Urban development in close proximity to Z. granulata sites is likely to cause modification of habitat through altered hydrological conditions and soil pH, soil nutrification, weed invasion, potential introduction of plant pathogens and altered fire frequency. Subsequent increases in pedestrian and/or vehicular traffic through sites may result in trampling, soil compaction, soil erosion and rubbish dumping.

    Other proposals that result in the regular slashing, grazing, herbicide spraying or burning of Z. granulata habitat are also likely to result in the modification of that habitat.

  • Damage to the soil seedbank
    Disturbances that will destroy or prevent germination of Z. granulata seed include rubbish dumping, the removal of leaf litter and topsoil, and spraying with residual herbicides that are capable of killing seeds in the soil. Frequent disturbances (from slashing, grazing, herbicide spraying or burning for example) may prevent the soil seed bank of the species from being recharged.

  • Altered fire regimes
    Proposals that result in the frequent burning (ie successive fires DEC 2005).

Threatening processes

There are five key threatening processes listed in Schedule 3 of the NSW Threatened Species Conservation Act 1995 (NSW TSC Act) that are potentially relevant to Z. granulata. These are:

  • Anthropogenic climate change;
  • Clearing of native vegetation;
  • Invasion of native plant communities by bitou bush and boneseed;
  • Invasion of native plant communities by exotic perennial grasses; and
  • High frequency fire resulting in the disruption of life cycle processes in plants and animals and the loss of vegetation structure and composition.

Other threatening processes include slashing and herbicide spraying to maintain paddocks and road verges, grazing and trampling by livestock, weed invasion, rubbish dumping (including green waste, household rubbish and construction materials) and the modification of habitat associated with urban development.

Viable population of the species

The viable population size for Z. granulata is unknown. In the absence of a detailed assessment demonstrating otherwise, all populations should be assumed to be viable.

A significant area of habitat

Assessment of habitat significance for Z. granulata requires consideration of the following:

  • The number of plants that are present, including consideration of the soil seed bank;
  • The proportion of the local population that is present at the site;
  • The location of the site in relation to the current distributional limits of the species;
  • The size, condition and connective importance of the habitat;
  • The uniqueness of the habitat; and
  • The management potential of site including the likelihood of ameliorating existing threatening processes.

The DEC considers all viable populations as occupying a significant area of habitat until such times as adequate and representative examples are conserved across the species range.

Isolation/fragmentation

Z. granulata habitat has been fragmented by habitat clearance for agriculture, quarrying, residential development and road construction throughout its range.

The distance between populations of Z. granulata that will create genetic isolation is unknown as the species pollen vectors are unknown. Seed dispersal is localised so interaction via this mechanism is unlikely.

The clearing of interconnected or proximate areas of habitat for the species (or its pollen vectors) is clearly undesirable as this may expose populations to an increased risk of genetic isolation and subsequent decline.

Regional distribution of the habitat

The known distribution of Z. granulata is confined to the Sydney Basin Bioregion as defined in the IBRA (Thackway & Cresswell 1995).

Limit of known distribution

The known distribution of Z. granulata extends from Oak Flats in the north to Toolijooa in the south. The western limit of distribution follows the upper slopes of the Illawarra escarpment.

An extant population of the species occurs at Kanahooka, eight kilometres north of Oak Flats. This population is likely to have been transported to the site via propagules contained in fill material (Mills & Jakeman 1993; Robinson 1999).

Adequacy of representation in conservation reserves or other similar protected areas

Z. granulata is not considered to be adequately represented in conservation reserves.

Critical habitat

Critical habitat has not been declared for Z. granulata.

For Further Information contact

Threatened Species Unit, Metropolitan Region, Environment Protection and Regulation Division, Department of Environment and Conservation (NSW), PO Box 1967, Hurstville NSW 2220. Phone 02 9585 6678.

www.npws.nsw.gov.au

References

Thackway, R. & Cresswell, I.D. (1995). An Interim Biogeographic Regionalisation for Australia: A Framework for Setting Priorities in the National Reserves System Cooperative Program. Version 4.0. Australian Nature Conservation Agency, Canberra.

Mills, K. and Jakeman, J. (1993) Survey of the rare plant species Zieria granulata (Rutaceae) Illawarra Region, New South Wales. Unpublished report prepared for Kiama Municipal Council.

Robinson M.V. (1999) Section 5A Assessment of the Endangered Zieria granulata at the proposed North Kiama By-pass. Unpublished report for the NSW Roads and Traffic Authority.

IMPORTANT DISCLAIMER

The NSW Department of Environment and Conservation and the editor expressly disclaim all liability and responsibility to any person, whether a purchaser or reader of this document or not, in respect of anything done or omitted to be done by any person in reliance upon the contents of this document although every effort has been made to ensure that the information presented in this document is accurate and up to date.