National recovery plan for the Downy Wattle (Acacia pubescens)

NSW National Parks and Wildlife Service
Environment Australia, February 2003
ISBN 0 7313 6504 6

6. Habitat

6.1 Landform and Geology

Acacia pubescens has been recorded on a variety of geologies including Tertiary Alluvium, Holocene Alluvium and Wianamatta Shale. The soils at the sites where A. pubescens occurs are characteristically gravelly soils, often with ironstone. There are also a few sites that occur on the interface between Sandstone and Shale soils (eg. Menai, Barden Ridge, Annangrove, Castle Hill, Pleasure Point). The topography of the habitat of the species is flat to gently undulating, a characteristic of the Cumberland Plain region (Bannerman & Hazelton 1989). The sites of A. pubescens range in altitude from 0 to 650 metres a.s.l. (NPWS 1998).

6.2 Climate

Acacia pubescens occurs across the range of climatic zones in Western Sydney. The highest average rainfall in this area occurs in the north-west with 1300 mm at Bilpin (Bannerman & Hazelton 1989). Most rainfall occurs in summer. Maximum daily average temperatures range from 30°C in January to 17°C in July at Penrith. Minimum daily average temperatures range from 17°C in January and 4°C in July at Penrith (Bannerman & Hazelton 1989). The winds are predominantly from the south-east during the summer and from the south-west and north-west during the winter (Doherty 1987 in Nash and Matthes 1995).

6.3 Vegetation

Acacia pubescens occurs in open woodland and forest, in a number of plant communities, which are listed in table 5 below. Most sites are within Cooks River / Castlereagh Ironbark Forest, Shale Gravel Transition Forest or Shale Plains Woodland.

Table 5. Ecological communities associated with A. pubescens
Community (as per NPWS 2000) Examples of sites
Alluvial Woodland Milperra, Fairfield, Horsley Park
Castlereagh Scribbly Gum Woodland Kemps Creek
Cooks River/Castlereagh Ironbark Forest Oakville, Georges Hall, Rookwood
Shale/Gravel Transition Forest Windsor Downs, Milperra, Prestons, Prairiewood
Shale Hills Woodland Prospect Reservoir
Shale Plains Woodland Prospect Reservoir, Bossley Park, Lansdowne
Shale/Sandstone Transition Forest Revesby, Annangrove, Castle Hill, Menai

The understorey species that occur with A. pubescens will depend upon the geology, disturbance and fire regime of the particular site. The species often associated with A. pubescens include Melaleuca nodosa, M. styphelioides, Angophora bakeri, Ozothamnus diosmifolius, Acacia parramattensis, Dillwynia sieberi, Pultenaea villosa, Bursaria spinosa, Acacia falcata, Exocarpos cupressiformis, Themeda australis, Lomandra longifolia, Microlaena stipoides, Aristida vagans, Austrodanthonia tenuior, Dianella longifolia, Lepidosperma laterale and other species characteristic of the above plant communities.

Stands of A. pubescens have been recorded in open, disturbed areas, surrounded by exotic species. Although these areas are clearly not the natural habitat of A. pubescens, the species may survive in these situations for many years, due to its suckering nature and ability to tolerate some levels of disturbance. These areas are important as they provide information as to the original extent of the species and they may contain examples of genetic variability that have been lost elsewhere.