THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this conservation advice on 01/04/2016. Conservation Advice Conostylis dielsii subsp. teres Irwin’s conostylis Conservation Status Conostylis dielsii subsp. teres (Irwin’s conostylis) is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act). The species is eligible for listing as prior to the commencement of the EPBC Act, it was listed as Endangered under Schedule 1 of the Endangered Species Protection Act 1992 (Cwlth). The main factors that are the cause of the species being eligible for listing in the Endangered category are a restricted extent of occurrence, a restricted number of locations, and continuing threats. Description Irwin’s conostylis is a tufted perennial herb, which grows to about 20 cm tall, and has leaves 13 to 33 cm long and less than 1 mm wide. The leaf bases are densely hairy, while the upper part of the leaf is less hairy. Irwin’s conostylis has a dense inflorescence composed of many flowers, held on a 4 -10 cm long stem. The individual flower stalks are short and each cream flower, 7.5 to 10 millimetres long, is tubular for a third to a half of its length then divides into six lobes. The flowers are covered with short, densely matted hairs. The petal lobes remain on the fruit and become claw- like, touching at the apex with gaps at the bases (Brown et al., 1998). Differs from Conostylis dielsii in the terete, not flat leaves, which are also slightly longer. Also similar to C. teretiuscula, which has silvery, villous hairs on the leaves and numerous ovules on the sides and lower part of the placenta (Patrick 2001). Distribution Irwin’s conostylis occurs in an area north-east of Dongara, in Western Australia In 2001 it was known from from three populations, two on road verges and one small population on a nature reserve (Patrick 2001). The total numbers are estimated at 1,640 plants known from nine populations that occur on Shire road reserves and a Nature Reserve. It is found on white, pale yellow or grey sand with lateritic gravel, in heath, open scrub, low open heath and low open woodland, in upland areas, and is quite inconspicuous when not in flower. Associated species include Allocasuarina species, Hibbertia hypericoides, Dryandra fraseri, Banksia scabrella, Ecdeiocolea monostachya and Hakea species. Relevant Biology/Ecology The genus Conostylis contains 45 species, all of which are endemic to the south-west of Western Australia. A number of species are grown as ornamentals and Irwin’s conostylis has the potential to be of horticultural significance. The genus Conostylis is comprised of a mixture of insect and bird-pollinated species (Hopper et al., 1987). This subspecies has small cream flowers borne during the period July-Aug (Hopper et al. 1987). The species grows in white, pale yellow or grey sand with lateritic gravel, in heath, open scrub, low open heath and low open woodland, in upland areas (Brown et al. 1998). Associated species include Hibbertia hypericoides, Hakea trifurcata, Eremaea beaufortioides and Allocasuarina humilis (Patrick 2001). Conostylis dielsii subsp. teres (Irwin’s conostylis) Conservation Advice Page 1 of 4 It is thought to regenerate after fire, like other members of the genus, from subterranean regenerative buds emerging from horizontal rhizomes (Gill 1981 in Patrick 2001) and that soil- stored seed germinates following summer fire, as in other species of Conostylis. Threats • Edge effects are influencing the populations restricted to narrow road reserves. The habitat of these populations have high perimeter to area ratios, and virtually the whole corridor is subject to edge effects from management of the adjacent land (Lynch 1987). Effects include the proximity of a weed seed source, increased wind speed, fertiliser and herbicide spray drift and runoff, modified hydrology, and altered disturbance regimes, including fire. The fragmentation of the corridors, combined with edge effects, results in the habitat being subject to high levels of stress and periodic acute disturbances. • Weed levels are high in narrow road reserve populations, and also occur at a lower level in populations near reserve boundaries or on wide road reserves. Weed invasion occurs as a result of edge effects such as increased nutrient levels (fertiliser runoff, rabbit droppings) and soil disturbance (rabbits, earthworks). Weed species include wild oats (Avena fatua), annual veldt grass (Ehrharta longiflora), other introduced annual grass species, cape weed (Arctotheca calendula) and wild turnip (Brassica tournefortii). At populations where the level of weed infestation is low, there is potential for weeds to invade further in the event of a disturbance such as fire. • Road, firebreak and fence maintenance are a threat to all road reserve populations. Firebreak and fence maintenance threatens populations at the boundaries of private property. Firebreak maintenance within the Nature Reserve that contains this subspecies is not currently a threat as threatened flora locations are considered in planning for fire management. Threats to road reserve populations include road widening, grading, chemical spraying, and construction of drainage channels and the mowing of roadside vegetation. • Rabbits are having a high level of impact on several road reserve populations. Rabbits do not appear to graze adult plants except in very dry seasons. However, the sandy soils of Irwin’s conostylis habitat are susceptible to disturbance from warrens and diggings. Rabbits also encourage weed invasion through soil disturbance, addition of nutrients to soil, and introduction of weed seeds. • Fire frequency during the reproductive phase (i.e. flowering, pollination, seed growth and seed dispersal) of Irwin’s conostylis may impact seedling recruitment. High fire frequency may lead to habitat degradation due to depletion of the soil seed bank and a temporary increase in the availability of nutrients for weed establishment (Panetta & Hopkins 1991). Appropriate occasional summer fire may be an important part of the life cycle of this subspecies and be necessary for regeneration. The role of fire in facilitating weed invasion needs to be considered as part of fire management planning; particularly for populations that occur close to reserve boundaries that adjoin cleared farmland, where monitoring and weed control will be necessary following any wildfire or prescribed burn. • Access for oil drilling is a potential threat to two populations, as an oil company has operations on the adjacent private property and machinery and vehicles use access tracks within the road verge near Irwin’s conostylis plants. Vehicles deviating from access tracks have the potential to cause direct damage to Irwin’s conostylis plants and also cause damage to the habitat. Conostylis dielsii subsp. teres (Irwin’s conostylis) Conservation Advice Page 2 of 4 Conservation Actions Conservation and management actions Invasive species • In populations heavily infested with weeds, implement weed control by spot spraying with herbicide during the appropriate weed growth phase, using low herbicide concentrations to minimise the impact on native vegetation. • Monitor minor weed infestations at other populations, and implement appropriate weed control if required (prompt control is required in the event of fire). • When the threat from rabbits is high, control rabbit numbers by baiting with 1080 oats in cooperation with adjoining property owners. Baiting should be done during summer when bait uptake is highest due to scarcity of food and water. Fire management • In consultation with land managers, develop a fire management strategy based on the outcomes of fire response trials. The strategy should include recommendations for fire control measures, fire intensity, timing and frequency. • Critically, any use of prescribed or experimental fires must be very well justified, and is typically an action of last resort. It must have a carefully planned weed management strategy and demonstrated funding to ensure post-fire monitoring and control actions occur (eg weed control based on sound scientific evidence). • Ensure that prescribed burns do not occur during the flowering period May to June. Noting that late autumn, winter and spring ignitions will have a highly detrimental effect upon the long-term viability and sustainability of the Irwin’s conostylis and is likely to have a deleterious impact on other native species that provide the natural community context for the splendid wattle. • Provide maps of known occurrences to local and state Rural Fire Services and seek inclusion of mitigation measures in bush fire risk management plans, risk register and/or operation maps. Stakeholder engagement • Liaise with relevant land managers and oil companies to ensure that populations are not accidentally damaged or destroyed. • Continue to consult with flora conservation staff with regard to fire management strategies within the Nature Reserve where Irwin’s conostylis occurs, and the implications of fire trials on fire response and appropriate fire regime for the subspecies. • Promote awareness of the subspecies to the community, which may lead to the discovery of new populations. Survey and Monitoring priorities • Monitor the visibility of Declared Rare Flora markers, which have been installed at all populations that occur on road reserves or near Nature Reserve