Zieria granulata (Illawarra Zieria) Recovery Plan

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

5 Distribution and Habitat

5.1 Definitions

5.1.1 Populations

Populations are defined by the International Union for the Conservation of Nature and Natural Resources (IUCN 1994) as geographically or otherwise distinct groups between which there is little [genetic] exchange, typically less than one migration per year. A migration in the case of plant species is considered to be the movement of seed propagules or pollen between populations. Where there is inadequate information on a species with which to assess the extent to which genetic material is exchanged (as is the case for Z. granulata), a population can be defined using the rule of thumb given by Keith et al. (1997) as a geographic discontinuity of more than 1 kilometre.

Consequently, in this recovery plan, discrete groups of Z. granulata plants that are not separated from other discrete groups by more than one kilometre are considered to be a single population. Following this definition, 26 populations of Z. granulata can be identified (see Section 6.3.2).

5.1.2 Sites and sub-sites

For this recovery plan, sites are defined as discrete groups of Z. granulata plants that are separated from other groups by an arbitrary distance of 200 metres or more. These sites have been labelled with the prefix Zg followed by a unique number (eg Zg1, Zg2 etc). Sites may also be termed populations if the distance to the nearest site is greater than one kilometre (see definition above).

Sites have been further divided into sub-sites (Zg1a, Zg1b etc) where discrete groups of plants at a site are separated from other groups of plants at that site by an arbitrary distance of 50 metres or more.

A total of 97 sites comprising 158 sub-sites have been recorded for Z. granulata.

5.2 Distribution

Z. granulata is endemic to the Illawarra region of NSW where it has been recorded from 26 fragmented populations (97 sites) between Oak Flats (Shellharbour LGA) and Toolijooa (Kiama LGA), a range of approximately 22 km. Within this range, the species is typically located on the coastal plain although occasional sites occupy the slopes of the Illawarra escarpment.

A disjunct site is recorded from Kanahooka (Wollongong LGA), 8 km north of Oak Flats. 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).

5.3 Land Tenure and Zoning

Tables 1 and 2 show the distribution of Z. granulata sites and plants by land manager and zoning respectively. It is clear that the vast majority of Z. granulata plants occur on freehold land that is zoned for extractive industry or rural land-uses.

It is noteworthy that, while only nine per cent of sites occur on land that is zoned for extractive industry, 32 per cent of recorded plants are located at such sites. Conversely, although 40 per cent of sites occur on land that is zoned for environmental protection, just 18 per cent of recorded plants are located at these sites.

Table 1: Z. granulata distribution by land manager
Land manager Plants* Sites**
Private landholder 8577 (73%) 66 (60%)
Kiama Council 1847 (16%) 25 (23%)
Crown 608 (5%) 2 (2%)
Shellharbour Council*** 300 (3%) 6 (6%)
Killalea State Park Trust 348 (3%) 4 (4%)
Roads & Traffic Authority 49 ( 3 (3%)
NPWS 10 ( 2 (2%)

* using the lowest estimate of total plant numbers at the 77 sites for which plant counts exist
** where a site extends over two tenures it has been recorded as two separate sites
*** includes two privately owned sites to be transferred to Council under approved developments

Table 2: Z. granulata distribution by zoning
Zoning Plants* Sites**
Extractive industry 3701 (32%) 9 (9%)
Rural land-uses 4138 (35%) 33 (32%)
Env. Protection 2078 (18%) 41 (40%)
Residential 1286 (11%) 6 (6%)
Open space*** 514 (4%) 9 (9%)
National Park 10 ( 2 (2%)
Arterial road 12 (0.1%) 1 (1%)

* using the lowest estimate of total plant numbers at the 77 sites for which plant counts exist
** where a site extends over two zones it has been recorded as two separate sites
*** includes two sites presently zoned residential that will be rezoned as open space under approved developments

5.3.1 Conservation reserves

Two sites have been recorded from the Minnamurra Rainforest section of Budderoo National Park. Ten plants (comprising one mature plant, six immature plants and three seedlings) were located at Zg30 in 2004, up from five plants (comprising one mature plant and four seedlings) when the site was discovered in 1995 (M. Robinson pers. comm.).

The 1953 Atlas of NSW Wildlife record for the other site within the park (Zg29) does not describe the number of plants present. The spatial accuracy of this record is low (to 1 km) and it is possible that the record actually relates to the same site as Zg30.

Zieria granulata species disrtibution map

5.3.2 Crown land

Four sites (Zg23 to Zg26) are located within Killalea State Park where Mills (1987) recorded a total of 348 Z. granulata plants. The Killalea State Park Trust coordinates the management of this park.

A further 25 plants have been recorded from crown reserves that are managed by Shellharbour City Council (Bass Point Reserve) and Kiama Municipal Council (Saddleback Mountain and North Kiama Park) (Table 3).

Two sites in the Dunmore Hills area are located on crown land that contains a state significant latite resource. Mills & Jakeman (1993) describe one of these sites (Zg20), which is located north of the Dunmore Quarry, as being part of a population that contains thousands of plants. The other site (Zg21) is located near the southern edge of the Dunmore Quarry and contained 108 plants when surveyed in 1992 (Robinson 2001).

5.3.3 Council owned land

Shellharbour City Council Three sites have been recorded within reserves that are managed by Shellharbour City Council (Table 3). A further two sites (Zg1 at Oak Flats and Zg22 at Shellcove) occupy freehold lands that will become council managed reserves under the conditions of

Table 3: Sites located within council managed reserves

consent for approved developments in adjacent areas. One site at Albion Park (Zg3) occupies operational council land that is zoned for residential development. The number of plants present at this site has not been documented.

Kiama Municipal Council (KMC) Twelve sites, including three sites that are located in crown reserves, have been recorded in reserves that are managed by KMC (Table 3). A further eleven sites occur, at least partially, on road verges that are managed by KMC (Table 4).

A site at Willow Creek (Zg60) occupies operational council land that is zoned for residential development. KMC is considering entering into a Voluntary Conservation Agreement with the DEC to protect this site which contains an estimated 1100 Z. granulata plants (M. Mulvaney, DEC, pers. comm.).

5.3.4 Freehold land

A total of sixty-six Z. granulata sites have been recorded on freehold properties. These sites predominantly occupy land that is zoned for rural land-uses or for environmental protection.

One freehold site at Toolijooa (Zg89), the southern most recorded location for the species, is partially protected under a property agreement negotiated between the landholder and DIPNR. One freehold site at Foxground (Zg84) is protected under a Voluntary Conservation Agreement with the DEC.

Location Site Code Plants LGA Source
Bass Point Reserve, Shellharbour Zg27, Zg28 5 Shellharbour M. Bremner pers. comm.
Elisabeth Brownlee Reserve, Albion Park Zg2 3 Shellharbour M. Bremner pers. comm.
Stoney Range Reserve, Oak Flats* Zg1 92 Shellharbour Robinson 1999
Unnamed reserve at Shellcove* Zg22 >200 Shellharbour M. Bremner pers. comm.
Kiama Aquatic Centre, Kiama Zg58 170 Kiama Mills & Jakeman 1993
Turpentine Reserve, Kiama Downs Zg51 12 Kiama Robinson 1999
Stead Reserve, Kiama Zg59 30 Kiama Mills & Jakeman 1993
Minnamurra Headland, Minnamurra Zg48 2 Kiama D. Black pers. comm.
Bonaira Native Gardens, Kiama Zg68** - Kiama NSW Wildlife Atlas
North Kiama Park, Bombo Zg94 7 Kiama Glaister pers. comm
Jerrara Dam, Jerrara Zg71, Zg72, Zg74, Zg75 269 Kiama Mills & Jakeman 1993
Saddleback Mountain Zg78, Zg79 13 Kiama Mills & Jakeman 1993

* privately owned sites to become Council reserves under approved developments
** possibly planted, source of propagative material unknown

Table 4: Sites located on road verges managed by Kiama Council

Table 4: Sites located on road verges managed by Kiama Council
Location Site Code Plants Source
Jamberoo Road Zg31, Zg32 17 Mills & Jakeman (1993)
Wallaby Hill Road Zg45, Zg46, Zg47 450* Mills & Jakeman (1993)
Saddleback Mountain Road Zg81 5 Mills & Jakeman (1993)
Old Saddleback Road Zg66 40 Mills & Jakeman (1993)
Saddleback Road Zg67 1 Mills & Jakeman (1993)
Mount Brandon Road Zg76, Zg90 293* Mills & Jakeman (1993); M. Bremner pers. comm.
Long Brush Road Zg64 15 Mills & Jakeman (1993)

*includes plants observed in adjacent paddocks

Twenty sites in the Dunmore Hills area occupy freehold land that is owned by mining interests. These sites are zoned for extractive industry, rural land-uses or for environmental protection.

A further five sites are located on freehold land that is zoned for residential development. Three of these sites (Zg56, Zg57 and Zg69) occur in Kiama LGA. The other two sites (Zg1 and Zg22) occur in Shellharbour LGA and are to become council reserves under the consent conditions of approved developments in adjacent areas.

5.3.5 RTA managed land

Two sites at Tabbagong Forest (Zg51 and Zg52) partially occur on RTA managed land. Thirty-five of the 114 Z. granulata plants present at these sites will be removed during construction of the North Kiama By-pass (Robinson 1999). A site (Zg50) containing two plants has also been recorded from RTA managed land near the Minnamurra Bends, Kiama Downs (Robinson 1999).

5.4 Habitat

5.4.1 Landform

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

5.4.2 Soil landscape

Table 5 shows the distribution of Z. granulata sub-sites and plants by soil landscape unit. The species has been recorded on 10 soil landscape units although the vast majority of sub-sites and plants occur within the Bombo soil landscape unit. It should be noted however that the occurrence of sites within the Mangrove Creek and Shoalhaven soil landscape units is considered to be highly unlikely. It is probable that these sites (Zg49 and Zg83) actually lie within the adjacent Bombo and Wattamolla Road units respectively.

Appendix 1 contains descriptions of the soil landscape units that have been recorded in association with Z. granulata.

Table 5: Distribution by soil landscape unit
Soil Landscape Unit* Plants** Sub-sites
Bombo 8421 (73%) 118 (74%)
Wattamolla Road 2043 (17%) 6 (4%)
Shellharbour 630 (5%) 9 (6%)
Kiama 472 (4%) 8 (5%)
Cambewarra 132 (1%) 7 (4%)
Jamberoo 29 ( 5 (3%)
Fountaindale 7 ( 1 (1%)
Albion Park 3 ( 2 (1%)
Mangrove Creek*** 2 ( 1 (1%)
Shoalhaven*** Not recorded 1 (1%)

*after Hazelton 1992
** using lowest estimate of total plant numbers at the 111 sub-sites for which plant counts exist
*** highly unlikely occurrence

5.4.3 Geology

Z. granulata has been recorded on 12 geological units although Bumbo Latite (a member of the Permian Gerringong Volcanics) is clearly the geological unit that is most closely associated with the species. Table 6 shows the distribution of Z. granulata sub-sites and plants by substrate.

Table 6: Z. granulata distribution by substrate
Geological Unit Rock Class Geological Period Plants* Sub-sites
Bumbo Latite Igneous Permian 10777 (93%) 109 (68%)
Budgong Sandstone Sedimentary Permian 401 (3%) 20 (12%)
Quaternary Talus Sedimentary Quaternary 357 (3%) 17 (8%)
Saddleback Latite Igneous Permian 64 ( 1 (1%)
Cambewarra Latite Igneous Permian 56 ( 1 (1%)
Blowhole Latite Igneous Permian 27 ( 2 (1%)
Quaternary Alluvium Sedimentary Quaternary 16 ( 4 (3%)
Irwins Creek Breccia Igneous Tertiary 10 ( 1 (1%)
Illawarra Coal Measures Sedimentary Permian 13 ( 4 (3%)
Quaternary Sand Sedimentary Quaternary 5 ( 2 (1%)
Bong Bong Basalt Igneous Tertiary 9 ( 1 (1%)
Saddleback Agglomerate Igneous Tertiary 4 ( 1 (1%)

* using lowest estimate of total plant numbers at the 111 sub-sites for which plant counts exist

5.4.4 Altitude

Table 7 shows the distribution of Z. granulata sub-sites and plants by altitude class. The altitudinal range of the species is 5 to 510 m, although the vast majority of sub-sites (89%) and plants (96%) occur below 150 m.

Table 7: Z. granulata distribution by altitude class
Altitude (m) Plants* Sub-sites
0-50 3057 (26%) 44 (28%)
51-100 1762 (15%) 57 (36%)
101-150 6425 (55%) 39 (25%)
151-200 334 (3%) 6 (4%)
201-250 - -
251-300 66 ( 3 (2%)
301-350 69 ( 5 (3%)
351-400 2 ( 1 (
401-450 - -
451-500 20 ( 3 (2%)
501-550 4 ( 1 (

* using lowest estimate of total plant numbers at the 111 sub-sites for which plant counts exist

5.4.5 Climate

The Illawarra area has a generally mild climate with extremes in temperature being moderated by coastal effects (Mills & Jakeman 1995). Average minimum and maximum temperatures are closely related to altitude and proximity to the coast (Table 8). Rainfall is very high compared with much of NSW.

Average annual rainfall figures range from just below 1000 mm near Lake Illawarra to over 1800 mm at Barren Grounds with the higher rainfall isohyets closely correlated to the top of the escarpment (Mills & Jakeman 1995). The distribution of rainfall within the area can also be attributed to winds blowing from the south (Hazelton 1992). One third of the areas mean annual rainfall occurs in January, February and March with a marked secondary rainfall peak in June (Hazelton 1992). Westerly airflows dominate the weather during winter producing cooler, drier conditions although few or no frosts occur on the coastal plain (Hazelton 1992). Drought conditions can occur in the area and rainfall data indicates the occurrence of distinct runs of wet or dry years which last between six and eight years (Mills & Jakeman 1995).

Robinson (1999) found that 80% of the 51 Z. granulata sites studied in that report occurred in an environment that received an average annual precipitation of between 1100 and 1400 mm.

Table 8: Average temperatures (°C) for Moss Vale and Wollongong climatic stations*
Station Altitude Distance inland Average January Maximum Average July Minimum Average annual maximum Average annual minimum
Moss Vale 672 m 45 km 21.6 1.2 19.4 6.8
Wollongong 12 m 0.5 km 25.9 7.8 21.6 12.6

*Source: Mills & Jakeman 1995

5.4.6 Associated Vegetation

Vegetation descriptions exist for 122 of the 158 recorded Z. granulata sub-sites. These descriptions have been categorised into ten broad vegetation types with an additional vegetation type (named regenerating scrub) used to describe isolated plants or small patches of regenerating vegetation located in open paddocks or on road verges. Table 9 shows the distribution of Z. granulata sub-sites and plants within these vegetation types.

Three vegetation types are considered to provide typical natural habitat for Z. granulata: 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 termed Melaleuca armillaris Tall Shrubland, Illawarra Subtropical Rainforest, and Illawarra Lowlands Grassy Woodland respectively.

Table 9: Distribution of Z. granulata by vegetation type
Vegetation type Plants* Sub-sites
Melaleuca armillaris (Bracelet Honey Myrtle) scrub to tall shrubland 4798 (41%) 24 (15%)
Rainforest 3474 (30%) 35 (22%)
Backhousia myrtifolia (Ironwood) low closed to open forest 1167 (10%) 3 (2%)
Isolated regrowth along paddocks/roads 986 (8%) 25 (16%)
Eucalyptus tereticornis (Forest Red Gum) woodland to open forest 678 (6%) 17 (11%)
Vegetation type not recorded 388 (3%) 36 (23%)
Eucalyptus paniculata (Grey Ironbark) open forest 152 (1%) 9 (6%)
Dodonaea viscosa ssp. angustifolia (Sticky Hop Bush) scrub to open scrub 70 (1%) 3 (2%)
Syncarpia glomulifera (Turpentine) woodland 17 ( 2 (1%)
Eucalyptus botryoides (Bangalay) open forest 4 ( 2 (1%)
Leptospermum laevigatum (Coastal Tea Tree) open scrub 3 ( 1 (1%)
Eucalyptus fastigata (Brown Barrel) forest 2 ( 1 (1%)

* using the lowest estimate of total plant numbers at the 111 sub-sites for which plant counts exist

Melaleuca armillaris scrub to tall shrubland

The greatest number of Z. granulata plants are recorded within the endangered ecological community, Melaleuca armillaris Tall Shrubland (MATS). The NSW Scientific Committee describes this community as occupying very dry ridgetops in the Dunmore Hills and Jamberoo Valley area of Shellharbour and Kiama LGAs, usually where volcanic soils overlay latite (NSW Scientific Committee 2002a).

The vegetation of MATS is dominated by M. armillaris to eight metres in height with a canopy varying from open to closed (QEM 1994). Occasional emergent E. tereticornis, Hibiscus heterophyllus and Alphitonia excelsa are present, as are sclerophytic and mesic understorey species including Dodonaea viscosa spp. angustifolia, Bursaria spinosa var. spinosa, Indigofera australis, Leucopogon juniperinus, Acacia mearnsii, Prostanthera linearis, Rapanea variabilis and Cassine australis (Black 2001; QEM 1994; M. Bremner, DEC, pers. comm.).

Groundcover density is greatest where the canopy is open, particularly where exposed rock occurs (QEM 1994). Groundcover species include Poa sieberana, Cymbopogon refractus, Microlaena stipoides, Dichelachne sp., Plectranthus parviflorus, Bracteantha bracteata, Calandrinia pickeringii, Lepidosperma laterale, Crassula sieberana, Wahlenbergia gracilis, Cheilanthes distans and Cheilanthes sieberi (NSW Scientific Committee 2002a; Black 2001; QEM 1994; M. Bremner, DEC, pers. comm.).

A scrub variation of MATS to 3 metres in height occurs with Z. granulata at Killalea State Park. The floristics here are variable with mesic understorey species including Commersonia fraseri, Pittosporum revolutum, P. undulatum and Guioa semiglauca dominating some sites and sclerophyllous species including Leptospermum laevigatum, Acacia sophorae and Acacia longifolia dominating others (Leonard et al. 2002).

Rainforest

The greatest number of Z. granulata sub-sites occurs in association with the endangered ecological community, Illawarra Subtropical Rainforest (ISR).

This rainforest community occupies high nutrient soils on the Illawarra coastal plain and escarpment foothills and has been extensively cleared for agriculture (NSW Scientific Committee 2002b). It includes the rainforest types described in Mills & Jakeman (1995) as subtropical, moist subtropical and dry subtropical (NSW Scientific Committee 2002b).

Z. granulata typically inhabits the drier rainforests of the coastal lowlands and only a few sub-sites are recorded from moister locations on the foothills and slopes of the Illawarra escarpment. Typical rainforest species recorded at Z. granulata sites include Notelaea venosa, Hibiscus heterophyllus, Alphitonia excelsa, Commersonia fraseri, Clerodendrum tomentosum, Alchornea ulicifolia, Pittosporum undulatum, P. multiflorum Croton verreauxii, Cassine australis and Streblus brunonianus (Mills & Jakeman 1993; M. Bremner, DEC, pers. comm.).

Within rainforest vegetation, Z. granulata usually occurs towards the edge of remnants, on rocky outcrops, or in regenerating stands. Consequently, dense infestations of Lantana (Lantana camara) characterise many of the rainforest sites that contain the species. Occasional plants occur under an intact canopy within relatively undisturbed stands of rainforest, however this is not common (M. Bremner, DEC, pers. comm.).

Backhousia myrtifolia low closed to open forest

Nine per cent of recorded Z. granulata plants occur in B. myrtifolia (Ironwood) dominated forest at just three sub-sites. These sub-sites are located at Toolijooa (Zg89a), Willow Gully (Zg60b), and Minnamurra Rainforest (Zg30).

Isolated regrowth along roadsides and paddocks

A large proportion of Z. granulata sub-sites (16%) occur in small patches of regenerating vegetation along roadsides and in paddocks. These sub-sites are generally highly degraded and subject to ongoing disturbance in the form of regular grazing and/or slashing (Mills & Jakeman 1993; M. Bremner, DEC, pers. comm.).

Eucalyptus tereticornis woodland to open forest

Z. granulata has been recorded in woodland to open forest dominated by E. tereticornis (Forest Red Gum) in association with E. eugenioides (Brown Stringybark) or E. quadrangulata (White Box) at 11 per cent of sub-sites. Both sclerophytic and mesic species are recorded from the understorey of these sub-sites, which form part of the Illawarra Lowlands Grassy Woodland endangered ecological community.

Understorey species that have been recorded from these sub-sites include Acacia mearnsii, Alphitonia excelsa, Croton verreauxii, Notelaea venosa, Geijera salicifolia var. latifolia, Commersonia fraseri, Melaleuca armillaris, Dodonaea viscosa ssp. angustifolia, Pittosporum multiflorum, Leucopogon juniperinus and Callistemon salignus. Groundcovers present include Poa labillardieri, Microlaena stipoides, Commelina cyanea, Dichondra repens and Einadia hastata (Mills & Jakeman 1993; QEM 1994; M. Bremner, DEC, pers. comm.).

Eucalyptus paniculata woodland to open forest

Z. granulata has been recorded growing in association with E. paniculata at nine sub-sites within Tabbagong Forest (Robinson 1999). Eucalyptus saligna X botryoides and Syncarpia glomulifera are co-dominant species at these sub-sites and a dry rainforest dominated understorey is present (Robinson 1999).

Dodonaea viscosa ssp. angustifolia scrub to open scrub

Robinson (1999) records two Z. granulata sub-sites at Tabbagong Forest (Zg53 and Zg55a) occurring in scrub dominated by D. viscosa ssp. angustifolia, in association with Acacia binervata and Alphitonia excelsa. Both of these sub-sites are described as being highly disturbed areas on the edge of pasture.

A sub-site (Zg6) located on a rock platform above acliff at Stockyard Mountain occurs in a scrub toopen scrub of D. viscosa ssp. angustifolia, inassociation with A. binervata and A. implexa.Understorey species present include Rapaneavariabilis and Backhousia myrtifolia (M. Bremner,DEC, pers. comm.).

Syncarpia glomulifera woodland

Two sub-sites (Zg31 and Zg32) occur inregenerating Syncarpia glomulifera woodland nearTurpentine Creek Bridge, Jamberoo (Mills &Jakeman 1993). The only other sub-sites where Z.granulata has been recorded in association with S.glomulifera are within E. paniculatum woodland toopen forest at Tabbagong Forest (Robinson 1999).

Eucalyptus botryoides open forest

A sub-site at Bass Point (Zg28) occurs in open forest dominated by E. botryoides and B. integrifolia. Understorey species present at this sub-site include Cassine australis, Synoum glandulosum, Breynia oblongifolia, Glochidion ferdinandi, Pittosporum revolutum, Acacia sophorae, Lomandra longifolia and Marsdenia rostrata (M. Bremner, DEC, pers. comm.). A sub-site on the banks of the Minnamurra River (Zg49) occurs in association with E. botryoides and littoral rainforest species (K. Glaister, Wollongong Botanic Gardens, pers. comm.).

Leptospermum laevigatum open scrub

A sub-site at Bass Point (Zg27) occurs in open scrub dominated by Leptospermum laevigatum with a closed understorey of Acacia sophorae, Breynia oblongifolia, Alphitonia excelsa, Polyscias elegans and Geitnoplesium cymosum (M. Bremner, DEC, pers. comm.).

Eucalyptus fastigata forest

Mills & Jakeman (1993) describe a Z. granulatasub-site (Zg84) that is located in regenerating E.fastigata forest at Foxground. Associated speciesinclude Acacia binervata, Acacia melanoxylon,Acmena smithii and Leptospermum morrisonii.