Biology and ecology
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The park is a region of high species diversity, especially the upland swamps, which are considered to be the most species-rich in the world for shrub/sedge vegetation. They contain over 140 plant species. These upland swamps have experienced no significant changes in the last 17,000 years and thus, are of great scientific importance as well as being listed as an endangered ecological community. Additionally, Stokes and O’Hares Creeks are classified as protected waters and the waters connected to O’Hares Weir are classified as Specially Protected Waters. This signifies that either no or very little discharges can occur within these waters. The park is of regional significance, having preserved local and diverse ecosystems and habitats that in other surrounding areas have been either damaged or destroyed.[citation needed]
Flora[edit]
Forked sundew (Drosera binata) in Dharawal National Park
The two dominant vegetation communities, sandstone woodland and eastern gully forest, have species compositions very different from that of the same communities in other areas. The species richness of dry sclerophyll forests, dry sclerophyll woodlands and heathlands are greater than in similar coastal communities within NSW. There are also vegetation communities which are not well represented in other existing Sydney sandstone conservation areas. The O’Hares Creek Shale Forest community, which has a low population density, and the black cypress pine of the Woronora Plateau, which is disconnected from other populations, are both classified as endangered.
Of the 510 recorded vascular plant species in the region, Persoonia hirsuta and Acacia bynoeana are listed as endangered and Acacia baueri ssp. aspera, Leucopogon exolasius, Pultenaea aristata and Melaleuca deanei are listed as vulnerable. Another 14 species are listed as rare or threatened native plants. A further 24 species are considered regionally significant due to being uncommon, and the park is important for eleven others as it is their southernmost habitat within the region.
Fauna[edit]
128 birds, 39 reptiles, 32 mammals, 23 frog, 5 fish, 2 crayfish, 1 shrimp, 1 freshwater mussel and 273 invertebrate species have been recorded in the park. Of these fauna, 23 vertebrate species are listed as threatened. Other species considered rare either generally or within the region are platypus (Ornithorhynchus anatinus), dusky antechinus (Antechinus swainsonii), greater glider (Petaurus breviceps), wombat (Vombatus ursinus), eastern grey kangaroo (Macropus giganteus), wallaroo (Macropus robustus), red-necked pademelon (Thylogale thetis), red-necked wallaby (Macropus rufogriseus) and peregrine falcon (Falco peregrinus). The largest population of koalas (Phascolarctos cinereus) in southern Sydney are found in Wedderburn, which is located in and around the park. Their breeding habitat runs along the creek lines of the O’Hares Creek and Georges River starting from the Stokes creek junction to north of Kentlyn. Koalas are endangered, and their population is in decline. The eastern pygmy possum, found in the park, is listed as vulnerable. There are also some regionally significant frog and reptile populations found in the park, including the giant burrowing frog (Heleioporus australiacus) and the great barred frog (Mixophyes fasciolatus). The broad-headed snake (Hoplocephalus bungaroides) and the red-crowned toadlet (Pseudophryne australis) inhabit exfoliated rock on the sandstone plateaus. This is a habitat that has been dramatically degraded and fragmented in other Sydney regions but which is relatively undisturbed within the park. Bushrock collection, usually for garden use, is considered to be a key threatening process for the snake and toadlet as they use the rocks for shelter. There are non-native fauna species found within the protected area include feral cats and dogs, rabbits, foxes, black rat, deer and mosquito fish.
The following species are of high priority as most of their habitats are in the Woronora Plateau: broad-headed snake (Hoplocephalus bungaroides), Littlejohn’s tree frog (Litoria littlejohni), spotted-tailed quoll (Dasyurus maculatus), large-footed myotis (Myotis macropus), east-coast free-tailed bat (Mormopterus norfolkensis), green tree frog (Litoria caerulea), grey-headed flying fox (Pteropus poliocephalus) and the southern emu-wren (Stipiturus malachurus). These species suffer from a variety of threats, chiefly habitat loss. The park is considered to be critical to the regional conservation of the beautiful firetail (Stagonopleura bella), tawny-crowned honeyeater (Gliciphila melanops), Rosenberg’s goanna (Varanus rosenbergi), and the eastern three-lined skink (Bassiana duperreyi).
Diverse freshwater fish species are found within creeks in the park, including the Macquarie perch (Macquaria ambigua), which is a threatened species. The freshwater species Cox’s gudgeon (Gobiomorphus coxii), long-finned eel (Anguilla reinhardtii), climbing galaxias (Galaxias brevipinni) and the Sydney (Euastacus australasiensis) and spiny crayfish (Euastacus spp.) are also found in the park.