THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this Conservation Advice on 15/07/2016. Conservation Advice Allocasuarina portuensis Nielsen Park sheoak Conservation Status Allocasuarina portuensis (Nielsen Park sheoak) is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act) effective from the 16 July 2000. The species was eligible for listing under the EPBC Act at that time as, immediately prior to the commencement of the EPBC Act, it was listed as Endangered under Schedule 1 of the Endangered Species Protection Act 1992 (Cwlth). Species can also be listed as threatened under state and territory legislation. For information on the listing status of this species under relevant state or territory legislation, see http://www.environment.gov.au/cgi-bin/sprat/public/sprat.pl The main factors that are the cause of the species being eligible for listing in the Endangered category are a very restricted extent of occurrence and area of occupancy, and a very low number of mature individuals. Description The Nielsen Park sheoak, a member of the Casuarinaceae family, is a slender shrub growing to 3 - 5 m with smooth bark and wiry, articulated (jointed) branchlets to 27 cm long, dark green and drooping to spreading in habit. The branchlet articles (segments between the joints) are cylindrical with numerous longitudinal rounded to angular ridges, 13 - 27 mm long and 0.8 - 1.0 mm in diameter, hairless and usually faintly waxy. The reduced (modified) leaves are small triangular ‘teeth’ that are 0.7 - 1.1 mm long, seven or eight per whorl (a ring-shaped arrangement of leaves) around the article, spreading in shape to curving backwards at the tip and are often slightly overlapping. The Nielsen Park sheoak is predominantly dioecious (male and female reproductive organs or flowers are borne on separate, individual plants). Inflorescences (flower-bearing structures) consist of alternating whorls of tooth-like bracts (modified leaves). Within each bract are two lateral bract-like structures and a single unisexual flower. The male inflorescences are catkin-like spikes shaped like a tight string of beads. Female inflorescences develop into cylindrical woody cone-like infructescences (fruit-bearing structures or cones) that are borne on stalks that are 2 - 15 mm long (NSW NPWS 2000; Wilson & Johnson 2000). Allocasuarina distyla (scrub sheoak) and A. littoralis (black sheoak), which are both dioecious species, occur in the same habitat as the Nielsen Park sheoak. The scrub sheoak can be distinguished from the Nielsen Park sheoak as it is a shorter shrub growing 1 - 3 m with branchlets usually coarse, article ridges with a yellowish longitudinal midline and furrows with obvious hairs, broadly triangular teeth-shaped leaves, and catkin-like male spikes that are occasionally shaped like a string of beads. The black sheoak can be distinguished from the Nielsen Park sheoak as it is a tree growing to 5 -15 m. It has fissured bark, more slender branchlets, article ridges without strong longitudinal mid-lines and furrows without obvious hairs, narrow triangular teeth, and the catkin-like male spike are never shaped like a string of beads (NSW NPWS 2000). Distribution Allocasuarina portuensis (Nielsen Park sheoak) Conservation Advice Page 1 of 9 The Nielsen Park sheoak was discovered in the south-eastern part of Nielsen Park in Vaucluse in the eastern suburbs of Sydney, NSW, in 1986. Nielsen Park is part of Sydney Harbour National Park (NSW NPWS 2000). The habitat in which the Nielsen Park sheoak was discovered (hereafter referred to as the species’ original habitat) was described as open heath/woodland to tall closed woodland on a steep slope above a sandstone headland approximately 20 m above sea level (NSW NPWS 2000). The shallow sandy soils at the site are highly siliceous, coarsely textured and devoid of a soil profile (Matthes & Nash 1994; NSW OEH 2015). Matthes and Nash (1994) described the vegetation in the original habitat as consisting of canopy tree species such as Ficus rubiginosa (Port Jackson fig), Angophora costata (smooth-barked apple), Elaeocarpus reticulatus (blueberry ash) and Glochidion ferdinandi (cheese tree), with a shrub layer of Pittosporum revolutum (wild yellow jasmine), Kunzea ambigua (white kunzea) and Monotoca elliptica (tree broom heath). The ground-covering flora in the habitat includes Lomandra longifolia (matrush), Dianella caerulea (blue flax-lily), Billardiera scandens (apple berry), Pteridium esculentum (bracken fern) and Entolasia species. As these vegetation types do not occur exclusively in Nielsen Park (Benson & Howell 1990, cited in NSW NPWS 2000), it is likely that the Nielsen Park sheoak once had a broader distribution, particularly along the southern foreshores of Sydney Harbour (NSW NPWS 2000). At the time of discovery, the species’ population consisted of 10 plants, eight individuals bearing female flowers (female individuals) and two bearing male flowers (male individuals), found within 100 m of each other at six locations (Brookhouse 1986 cited in NSW NPWS 2000). By February 1998, this number had decreased to only two female individuals (NSW NPWS 2000). This original wild population is now extinct (NSW OEH 2015). Individuals of the species have been successfully propagated and introduced at a number of locations on similar soils in Nielsen Park and in a variety of vegetation types at other sites at The Gap bluff and Hermit Point in Sydney Harbour National Park, and Vaucluse Park and Gap Park (NSW NPWS 2000; NSW OEH 2015). While the total number of cultivated individuals of the species at the latter sites is undisclosed, 90 individuals are currently growing in Nielsen Park (NSW OEH 2016). All of the Nielsen Park sheoaks at the ex situ sites in Nielsen Park and other abovementioned sites have grown quickly and produced an abundance of fruit/seed, however they are now entering senescence. No Nielsen Park sheoak populations (or subpopulations) have been found during subsequent surveys of the Sydney Harbour foreshore, including all potential habitats and some unlikely habitats (Ibbetson pers. comm. 2016). Given that the Nielsen Park sheoak is listed as Endangered, any habitat where subpopulations of the species are known to occur is considered ‘habitat critical to the survival of the species’. Similarly, all subpopulations of the species are considered to be ‘important populations’ that are necessary for the species’ survival and recovery. In 2000, approximately 30 Nielsen Park sheoaks were propagated from seed and planted in the Royal Botanic Gardens, Sydney, NSW; the Australian Botanic Garden at Mount Annan, NSW; and the Australian National Botanic Gardens in Canberra, ACT (NSW NPWS 2000). The ex situ collections at Mount Annan (Ibbetson pers. comm. 2016) and at the Australian National Botanic Gardens (ANBG 2016) are intact and maintained. Relevant Biology/Ecology Certain aspects of the biology and ecology of the Nielsen Park sheoak are unknown. However, given the species’ similarity to closely related Allocasuarina spp. and other members of the Casuarinaceae family, available information on the biology and ecological requirements of these species is likely to be relevant to the Nielsen Park sheoak (NSW NPWS 2000). The Nielsen Park sheoak flowers from April to August, although many of the cultivated individuals planted in situ (in the species’ original habitat) have been known to flower during January and March. While virtually all of the known Nielsen Park sheoaks are dioecious, one cultivated individual planted in Nielsen Park is multi-stemmed and monoecious: the individual Allocasuarina portuensis (Nielsen Park sheoak) Conservation Advice Page 2 of 9 bears both male and female reproductive parts (NSW NPWS 2000). Exhibiting both monoecy and dioecy is common in Allocasuarina species (Wilson pers. comm. cited in NSW NPWS 2000). Like other species in the Casuarinaceae family, the Nielsen Park sheoak is wind pollinated. The number of cones produced by a fertile subpopulation is dependent on the number of female individuals present and the availability of pollen (i.e. the number of male individuals of the species or of other Allocasuarina spp. nearby) (NSW NPWS 2000). At several of the planted locations, there is little or no source of Nielsen Park sheoak pollen available. Therefore, it is likely that some of the seed present will belong to one or more hybrids of the Nielsen Park sheoak and the other Allocasuarina species present in the local area, the scrub sheoak or the black sheoak (NSW NPWS 2000). Fruit of species in the Casuarinaceae family are referred to as samaras (winged nut-fruits). In the genus Allocasuarina, samaras are produced inside the woody cone and are held there by woody valves. Due to their seed-like appearance, the samaras of the relevant Allocasuarina species are hereafter referred to as ‘seed’. From observations, it is clear that the species grows rapidly, flowers and produces cones within approximately 2-3 years. They continue to grow and fruit vigorously for a few more years and then the growth rate slows. Tozer (pers. obs. cited in NSW NPWS 2000) observed that most of the fertile cultivated individuals planted in situ produced more than 100 cones each (two individuals had more than 500). By 10 years of age, there is little further growth; flower, cone and seed production is greatly reduced; and branches start to die (Ibbetson pers. comm. 2016). The age of the original plants was considered most likely to be related to the occurrence of the last wildfire. Given that the two plants remaining at the original site in 1998 appeared to be very old and senescing 30 years after the estimated time of the previous fire, the longevity of the species was estimated to be 30 years (NSW NPWS 2000). While it seems that some individuals may be able to survive this long, they are senescent and will not have been producing fruit for many years (Ibbetson pers.