Indicative distribution
The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas.
(
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The information presented in this map is only indicative and may contain errors and omissions.
Scientific name: Zieria involucrata
Gazetted date:
13 Dec 2002
Profile last updated:
21 Aug 2019
Description
A small, erect, sparse shrub, growing 1 – 2 metres in height. Branches and leaves are densely covered with hairs which form a soft, velvety covering (tomentum). When looked at under magnification most hairs appear star-shaped, although simple and two-forked hairs are also present. Leaves are opposite and consist of either a single leaflet or three leaflets, with both forms usually being present on the same branch (occasionally unifoliolate leaves only are present on a branch). Leaflets are dark green above, light grey-green below, oblong to elliptic to lance-shaped, 3 – 6 cm long and 6 – 15 mm wide. The flower clusters, consisting of 3 – 21 flowers, are shorter than the leaves and enclosed in numerous small, leaf-like bracts, 7 – 12 mm long, which are also covered in dense, white hairs. Flowers are white with pink tinges, and slightly hairy.
Distribution
Has a disjunct distribution north and west of Sydney, in the Baulkham Hills, Hawkesbury, Hornsby and Blue Mountains local government areas. Recent records for the species come from 22 populations in the catchments of the Macdonald, Colo and Hawkesbury Rivers between Melon Creek and Mogo Creek in the north to Little Cattai Creek (Hillside) and Wheeny Creek (Colo) in the south and from a single population in the upper Blue Mountains north of Katoomba. In addition, historical records exist for at least two other localities in the eastern Blue Mountains: south of Springwood Valley Heights and north-west of Kurrajong.
Habitat and ecology
- Occurs primarily on Hawkesbury sandstone. Also occurs on Narrabeen Group sandstone and on Quaternary alluvium.
- Found primarily in sheltered forests on mid- to lower slopes and valleys, e.g. in or adjacent to gullies which support sheltered forest, although some populations extend upslope into drier vegetation. Also known from at least two atypical ridgetop locations. The canopy typically includes Syncarpia glomulifera subsp. glomulifera (Turpentine), Angophora costata (Smooth-barked Apple), Eucalyptus agglomerata (Blue-leaved Stringybark) and Allocasuarina torulosa (Forest Oak).
- Ecological knowledge about this species is limited.
- Flowering usually takes place in spring. Plants usually first flower and set seed 3 – 5 years after germination, but maximum seed production probably does not occur until 6 – 10 years of age.
- While there is some evidence that individual plants may be capable of resprouting after fire, the species is probably best considered as an obligate seeder that relies on seed germination after disturbance to maintain populations. A soil seedbank, which may last 1 – 2 decades, appears to be established by this species, so for a number of years following fire or other disturbance the species may not be apparent, but be present only as seed in the soil.
- Either heat or smoke or a combination of these factors may play a role in breaking soil-stored seed dormancy. Both the amount of smoke and the level of heating could influence germination success. A certain level of heat may be optimal for breaking seed dormancy (such that too little heat results in seeds staying dormant, while too much heat kills seeds).
Regional distribution and habitat
Click on a region below to view detailed distribution, habitat and vegetation information.
Threats
- The main threat to the species is likely to be the impact of a frequent fire regime. If the fire interval is shorter than the period between germination and seed production, recruitment to the soil-stored seedbank will be limited or not occur at all and post-fire regeneration will deplete the existing seedbank. Three or more fires in close succession may therefore result in population decline or extinction.
- Sustained high frequency can also lead to a reduction in vegetation structure and subsequent changes in microclimate, affecting the suitability of the habitat for the species which appears to require moister, sheltered aspects.
- Fires of an inappropriate intensity that fail to break soil-stored seed dormancy (too cool) or kill soil-stored seed (too hot) may lead to population decline.
- Fragmentation and probably direct loss of habitat has occurred, and is likely to continue to occur, as a result of native vegetation clearing or modification for semi-rural and urban expansion and agricultural development. Several populations are on former Crown land that has been converted to private property.
- Road use and management, including mechanical methods for roadside vegetation management or bushfire fuel hazard reduction, where populations are proximate to roads, utilities and other assets.
- Legal or illegal bush rock removal may destroy plants and degrade the habitat of the species, as it often occurs in areas where Hawkesbury sandstone outcrops.
- Rubbish dumping.
- Grazing by domestic stock or feral animals may impact directly on the species, or lead to degradation of vegetation structure and floristics though trampling, erosion and the spread of weeds.
- Weed invasion (particularly Lantana).
- May be adversely affected by changes to habitat or fire regimes caused by climate changes resulting from or accelerated by human activities (see the NSW Scientific Committee Determination 00/24 for further information about this key threatening process). With a restricted distribution and fragmented populations, it may be especially susceptible to reductions in the bioclimatic range caused by climate change.
- Little knowledge about the veracity of historical records; potential for the discovery of additional populations to significantly increase the viability of the species.
- Physical disturbance due to legal/illegal access by trail-bikes, horse riders and four-wheel drive vehicles.
Recovery strategies
Priority actions are the specific, practical things that must be done to recover a threatened species, population or ecological
community. The Office of Environment and Heritage has identified
25 priority actions
to help recover the Zieria involucrata in New South Wales.
Activities to assist this species
- Prevent frequent fires from impacting on the populations. Presently, the recommended minimum fire-free interval is 10 years plus an additional 3 years in each of which seed production occurs. This recommendation may be modified in light of further research.
- At appropriate intervals, fires of moderate to high intensity, or fires of low intensity that move slowly and fully combust a high proportion of ground fuels, should be planned and implemented to generate a level of heat suitable to break seed dormancy.
- Minimise habitat loss, fragmentation or disturbance by retaining native vegetation containing the species and maintaining connectivity between populations.
- Ensure that road and track maintenance and construction and weed control activities are planned and implemented to take account of the presence of the species and to avoid damaging individual plants or degrading habitat for the species.
- Remove rubbish and inhibit further dumping.
- Seek conservation agreements with land owners.
- Survey potential habitat for new populations.
Information sources
- Armstrong, J.A. (1991) Zieria. In Harden, G.J. (ed.) Flora of New South Wales. Volume 2. New South Wales University Press, Sydney.
- Armstrong, J.A. (2002) Zieria (Rutaceae): A systematic and evolutionary study. Australian Systematic Botany 15, 277-463.
- Auld, T.D. (2001) The ecology of the Rutaceae in the Sydney region of south-eastern Australia: poorly known ecology of a neglected family. Cunninghamia 7(2): 213-239
- Auld, T.D., Keith, D.A. and Bradstock, R.A. (2000) Patterns in longevity of soil seedbanks in fire-prone communities of south-eastern Australia. Australian Journal of Botany 48(4):, 539-548
- Department of Environment and Conservation (NSW) (2005) Draft Recovery Plan for Zieria involucrata. NSW DEc, Sydney.
- Fairley, A. (2004) Seldom seen: rare plants of greater Sydney. (Reed New Holland, Sydney)
- NSW National Parks and Wildlife Service (2004) Draft Zieria involucrata Recovery Plan. NSW DEC, Hurstville.
- NSW Scientific Committee (2002) Zieria involucrata (a shrub) - Endangered species determination - final. DEC (NSW), Sydney.
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