Irenepharsus trypherus (Illawarra Irene) Recovery Plan

NSW Department of Environment and Conservation, 2005
ISBN: 1 7412 2145 5

Appendix 2: Profile and Environmental Impact Assessment Guidelines

THREATENED SPECIES INFORMATION Irenepharsus trypherus Hewson

Common Name: Illawarra Irene

Conservation Status

Irenepharsus trypherus is listed as an endangered species on Schedule 1 of the NSW Threatened Species Conservation Act 1995 and as an endangered species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.

Description

I. trypherus (Brassicaceae) is a hairless annual or short-lived perennial herb growing to 250 cm. It has a spreading to erect habit and is often multi-stemmed. Stem leaves are simple, petiolate, toothed, linear to elliptic in shape, and mostly 4 to 8 cm long. Its inflorescence is an elongated raceme of white flowers with petals to 4 mm long. The fruit is an upright linear pod (siliqua) to 20 mm long with seeds that become sticky when wet (Hewson 1982; Retter & Harden 1990; M. Bremner, DEC, pers. comm.).

I. trypherus is superficially similar to the weed species Ageratina riparia (Mistflower) with which it co-exists at a small number of sites. However, the flowering period of I. trypherus extends from December to June while Mistflower flowers between June and November (DEC 2005).

Distribution

I. trypherus is a NSW endemic that has been recorded from 17 sites within the local government areas (LGAs) of Kiama, Shellharbour, Shoalhaven, Wingecarribee and Wollongong.

The main distribution of the species extends for 41 kilometres from Marshall Mount in southern Wollongong LGA to Lake Yarrunga in Wingecarribee LGA. One site has been recorded outside this range in Ettrema Gorge, Morton National Park, which is located approximately 29 kilometres south of Lake Yarrunga (DEC 2005).

Recorded occurrences in conservation reserves

I. trypherus has been recorded from the following conservation reserves:

  • Macquarie Pass National Park;
  • Budderoo National Park; and
  • Morton National Park.

Habitat

I. trypherus typically inhabits steep rocky slopes near cliff lines and ridge tops. These slopes are frequently unstable and susceptible to small-scale erosion events. Associated soils are generally derived from volcanic or fertile sedimentary rocks. The species is less typically found growing out of crevices or on narrow benches along cliff lines (DEC 2005). The vast majority of I. trypherus sites are located on the upper slopes of the ridge systems that extend south and east of the Illawarra escarpment (ie Stockyard Mountain, Marshall Mount, Johnstons Ridge and Hindmarsh Ridge). The species has also been recorded from the deep sandstone gorges of the Shoalhaven River and its tributaries (DEC 2005).

Two records for the species from the 1940s are for sites on the floodplain of the upper Kangaroo River. This is highly unusual habitat for I. trypherus and it is suspected that these records actually refer to locations on the nearby escarpment slopes (DEC 2005).

I. trypherus sites are generally located at the ecotone of sclerophyll forest and rainforest. DEC (2005) describes the following associated vegetation types:

  • Eucalyptus tereticornis (Forest Red Gum)
  • E. quadrangulata (White Box) moist open forest to woodland;
  • E. quadrangulata - E. muelleriana (Yellow Stringybark) moist open forest;
  • E. tereticornis - E. eugenioides (Thin- leaved Stringybark) moist open forest; and
  • E. quadrangulata - E. fastigata (Brown Barrel) moist woodland;
  • E. piperita (Sydney Peppermint) - E. saligna X botryoides grassy open forest;
  • Backhousia myrtifolia (Ironwood) low closed forest;
  • Subtropical rainforest; and
  • Mixed subtropical - warm temperate rainforest.

The altitudinal range of the species is 85 to 400 m with the vast majority of sites recorded between 150 and 340 m.

Ecology

Little is known about the biology and ecology of I. trypherus. In ideal conditions the species can survive as a perennial for up to three years and is capable of reshooting from damaged or desiccated stems following light grazing, trampling or extended dry periods (A. Bofeldt, Wollongong Botanic Gardens, pers. comm; M. Bremner, DEC, pers. comm.).

I. trypherus flowers are morphologically hermaphrodite (ie each flower contains both male and female reproductive parts) although it is unknown whether the species is capable of self-pollination. The pollination mechanisms of the species are unknown although wind and insect pollination have been reported for other Brassicaceae species (Treu & Emberlin 2000).

Two types of flies have been observed visiting I. trypherus flowers and are considered to be potential pollinators. One species was identified as a type of hoverfly (family Syrphidae, subfamily Syrphinae) and is almost certainly a generalist pollen feeder. The other species could be identified only as a type of bee fly (family Bombyliidae) (D. McAlpine, Australian Museum, pers. comm.).

The flowering period of I. trypherus is December to June with fruits maturing from February. The species is thought to be a prolific seeder, although the viability and longevity of the seed is unknown. Disturbance and light levels are expected to influence recruitment (DEC 2005).

Threats

Threats recorded at I. trypherus sites include habitat clearance, weed invasion, erosion, and grazing and trampling by livestock and feral/native animals (DEC 2005).

Management

Management should involve the protection of habitat for I. trypherus and the active management of threats. Appropriate threat abatement measures include bush regeneration to restore and maintain suitable habitat, and fencing to restrict access by livestock and machinery. Control of feral animals (including deer and goats) is required at some sites (DEC 2005).

Monitoring is required to determine the extent and intensity of threats at extant sites and to measure the response of the species to threat abatement measures. Given the erosion prone nature of many I. trypherus sites, extreme care must be taken to minimise disturbance during monitoring or threat abatement works (DEC 2005).

Targeted survey is required to determine the extent of the species distribution. Initiatives to raise awareness of the species amongst landholders, public authorities and the general public are also required to avoid inadvertent damage to the species and encourage involvement in the recovery effort (DEC 2005).

An ex-situ seed collection for the species is needed to safeguard against the loss of genetic material that may result from local extinctions (DEC 2005).

Recovery Plans

A recovery plan for I. trypherus 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

Hewson, H.J. (1982) Brassicaceae (Cruciferae). In Flora of Australia: Volume 8 Lecythidales to Batales. Pages 231-357. Australian Government Publishing Service, Canberra.

DEC (2005) Irenepharsus trypherus (Illawarra Irene) Recovery Plan. Department of Environment and Conservation, Hurstville.

Retter, L. & Harden, G.J. (1990) Brassicaceae. In Harden G.J. (Ed.) Flora of New South Wales: Volume 1. Pages 459-486. New South Wales University Press, Kensington.

Treu, R. & Emberlin, J. (2000). Pollen dispersal in the crops Maize (Zea mays), Oil seed rape (Brassica napus ssp. oleifera), Potatoes (Solanum tuberosum), Sugar beet (Beta vulgaris ssp. vulgaris) and Wheat (Triticum aestivum): Evidence from Publications. Unpublished report prepared for the Soil Association.

IMPORTANT DISCLAIMER

The Department of Environment and Conservation (NSW) 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.

ENVIRONMENTAL IMPACT ASSESSMENT GUIDELINES

Irenepharsus trypherus

Hewson

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

I. trypherus is a cryptic species that occupies sites in low numbers. Survey for the species should be undertaken during its flowering period (December to June) when plants are easier to locate. Surveys should be avoided during or immediately following prolonged dry periods when mature plants are likely to have died-off.

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

Life cycle of the species

The ecology of I. trypherus is described in the recovery plan and summarised in the species profile. Proposals that are likely to impact upon the lifecycle 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 affected.
  • Fragmentation of habitat
    As the breeding system of I. trypherus is not understood, the effects of loss and fragmentation of its habitat are not known. Total destruction of habitat will place a population at risk of extinction.
  • Modification of habitat
    The modification of I. trypherus habitat will affect recruitment of the species. Such modification may result from weed invasion, erosion, or grazing and trampling by livestock and feral animals.
  • Damage to the soil seedbank
    Disturbances that will destroy or prevent germination of I. trypherus seed include the dumping of fill material, removal of topsoil, and spraying with residual herbicides that are capable of killing seeds in the soil. Regular grazing and slashing of the species may prevent the soil seed bank of the species from being recharged.
  • Altered fire regimes
    Proposals that result in an increase in fire frequency at I. trypherus sites are considered likely to impact upon recruitment of the species.

Threatening processes

Clearing of native vegetation” is the only key threatening processes (KTP) listed on Schedule 3 of the NSW Threatened Species Conservation Act 1995 (TSC Act) that has been observed to affect I. trypherus.

Other KTPs that may affect the species are:

  • High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition; and
  • Anthropogenic climate change.
The NSW Scientific Committee made a preliminary determination to list Herbivory and environmental degradation caused by feral deer as a KTP in October 2003. If a final determination is made to proceed with the listing of this KTP, it will be of relevance to I. trypherus.

Other threatening processes relevant to the species include weed invasion, erosion and grazing and trampling by livestock and feral/native animals (DEC 2005).

Viable local population of the species

The viable population size for I. trypherus is unknown. The species has been recorded growing in very low numbers at some sites (for example, even as one individual) and extreme fluctuations in plant numbers have been observed over time at some sites (DEC 2005). Consequently, low population numbers should not be used as an indicator of non-viability of the population.

A significant area of habitat

As I. trypherus is currently known from only a small number of sites, all of its currently occupied habitat should be considered to be significant.

Isolation/fragmentation

The distance between populations of I. trypherus that will create genetic isolation is unknown, as its pollen vectors and seed dispersal mechanisms are unknown. The clearing of interconnected or proximate areas of habitat for the species (or its pollen/seed vectors) is clearly undesirable as this may expose populations to an increased risk of genetic isolation and subsequent decline.

Regional distribution

The distribution of I. trypherus is confined to the Sydney Basin Bioregion, as defined in the Interim Biogeographic Regionalisation of Australia (Thackway & Cresswell 1995).

Limit of known distribution

The known historical distribution of I. trypherus extends from Marshall Mount in southern Wollongong local government area to Ettrema Gorge (Morton National Park) in Shoalhaven local government area.

Adequacy of representation in conservation reserves

I. trypherus is not considered to be adequately represented in conservation reserves.

Critical habitat

Critical habitat has not been declared for I. trypherus.

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

DEC (2005) Irenepharsus trypherus (Illawarra Irene) Recovery Plan. Department of Environment and Conservation, Hurstville.

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.

IMPORTANT DISCLAIMER

The Department of Environment and Conservation (NSW) 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.